Copyright (c) S. Waldee 2013 - All Rights Reserved
The Horsehead Project:
19th Century Study of Bright and Dark Nebulae
Stephen R. Waldee (c) 1990-2013 - All Rights Reserved
The Discovery of the "Horsehead Nebula" in the 19th Century, and other developments related to the study of faint and dark nebulae by eye and early astrophotography. (Some improved images, and additional text, added in 2012 and 2013.)
Exactly one hundred years ago [written in 1990] in the 1890 issue of the Annals of Harvard College Observatory, the astronomical world at large was routinely informed of the discovery of what we now regard as one of the most beautiful objects in the heavens, the unique and mysterious dark nebula known as ''The Horsehead.''
During the next several decades, it was to capture the attention of some of the world's leading celestial scientists and theorists, and would eventually become familiar to the interested public from images of its striking beauty that required the machinery of the greatest telescopes, and the patience of the most dedicated astrophotographers.
For many decades the prey of only the elite of professional astronomers and photographic technicians, the Horsehead can now be captured by the dedicated amateur visual astronomer. Thanks to the efficiency of today's precision-made yet inexpensive coated optics, narrowband nebular filters, and fast film emulsions, the Horsehead's fascinating shape and dark contrast may be enjoyed by means of simple, modest equipment well within the budget of many amateurs who want to challenge themselves to one of the ultimate tests of astronomical skill.
The author served for two years as a telescope salesman, demonstrating rows of shiny new Schmidt-cassegrains in sight of the famous David Malin UK/Australian telescope poster of the Horsehead. A frequent customer query about the visibility of this nebula, so clear and sharp in photographic time exposures, yet so evasive to the visual observer, led the author and a small group of diligent amateurs to undertake our project:
(a) to track down the history of historical sightings and photos;
(b) to test the visibility of the nebula in the smallest-aperture optics under varying sky conditions;
(c) to attempt to produce professional quality pictures with the simplest equipment, and
(d) to uncover the seemingly-lost origin of the popular nickname of this beautiful object.
In pursuing his detective work, the author began to wish he were an astronomically-minded Herman Melville, so exhausting yet exhilarating was the search for this elusive dark horse, as tantalizing as the great white whale was to Captain Ahab! In seeking answers, we encountered many unexpected episodes that may overturn a few misconceptions and inaccuracies, and will at last do justice to a few historical figures who have not received their full credit.
This paper will cover the Horsehead's discovery, and initial study, during the 19th-century transition from visual to photographic astronomical observation, from the perspective of an amateur astronomer who, as a volunteer at Lick Observatory, was privileged to study the great organization's archival material in quest of knowledge of the techniques used by professional astronomers at the eyepieces of the great telescopes in the pre-photographic era.
THE LURE OF THE NEBULAE
''Hier ist wahrhaftig ein Loch im Himmel'' -- here is truly a hole in Heaven -- cried Sir William Herschel, the greatest astronomer at the end of the eighteenth century and the possessor of the world's largest telescope, of 40-foot focal length and 48 inches of aperture. While sweeping a star cloud near the borders of the constellations Scorpio and Ophiuchus, Sir William thus cried out in astonishment as a deep black spot drifted into the field, otherwise crowded with myriads of stars and nebulosity that only his gargantuan telescope could reveal.
Bright nebulae, such as the great cloud in Orion, (discovered by the Frenchman Peiresc in 1610, a scant few years after the first simple spyglass telescopes were invented), (2) had slowly accumulated in number as instruments, observers, and sky charts improved by the 1700s.
Yet professional astronomers were most likely to study positions of the stars for aid in surveying, time-keeping, and determining locations of the planets and Moon; (3) expenditures for such studies could always be justified by governments for their practical benefits in navigation, even warfare.
Owen Gingerich writes that "to the astronomer of 200 years ago, it was the static, nondescript nebulae that were trivial." (4) But a holdover of earlier superstitious times was an avid interest in the nebulae that moved across the sky: comets. The first nebular catalogue, an amateur pursuit compiled by Messier and Mechain, listed fuzzy-looking patches not to be mistaken for new comets, and described many objects known well to earlier observers; even the first entry M1, the ''Crab'' nebula, was found previously by J. Bevis. (5)
Friedrich Wilhelm Herschel, born into a long established German musical family, terminated childhood early in 1753 as a teenaged wind player in the British King's German mercenary army; but threats of war prompted his father, Isaac, to send him to England. Now "William", he might have seemed to be an unlikely future candidate for scientific immortality, but, as Dr. J. L. E. Dreyer (astronomer and compiler of the New General Catalogue) wrote in the 1912 edition of Herschel's papers, "The indomitable energy and perseverance which had made Isaac Herschel overcome all obstacles and succeed in becoming a musician, was inherited by his brilliant son and enabled him to make good the deficiencies of his education... he... worked for years at mathematics, physics, and the theory of music, but the turning point of his life came... when the study of Smith's Optics roused in him the desire to see for himself the wonders of the heavens described in that book. In the spring of 1773... he began to devide his leisure hours between attempts at making telescopes and continuing his reading...retiring to bed with a basin of milk or glass of water and Smith's Harmonics or Optics, Ferguson's Astronomy &c, and so went to sleep buried under his favorite authors... He soon commenced keeping a careful record of his work in making telescopes, which he continued throughout his life till December 1818. It enables us to follow him step by step in the work which culminated in the 40-foot reflector..."
William began to turn his newest large reflector telescope on certain obscure and mysterious patches of light during the year that Messier published the first 68 of his nebulous-object discoveries. (6) In small or defective instruments they appeared as unresolved smudges; with better optics, some of the images were clarified into star clusters or chance stellar-alignments, called asterisms; yet many failed to coalesce into point-sources of light. Thanks to his efficient telescopes, it was solely Herschel's opportunity to discern and catalogue approximately 2,500 nebulae and star clusters, many not seen again for the large part of a century. Ultimately he was able to construct his 48-inch ''speculum'' -- as reflectors were known, named after the metallic compound of their shiny mirrors.
More than 200 years' accumulation of tarnish has dulled Herschel's original 1785 speculum for the 40-foot telescope.
Herschel determined that only 67% of available light was reflected by a freshly-polished speculum, as used without a diagonal secondary in the unobstructed Herschelian telescope. (7) From this we can calculate that before tarnish robbed the mirror of its luster, the great 48-inch instrument of 1789 was equivalent to about a contemporary 42-inch aluminized mirror with about 88% reflectivity, with a protective overcoating to prevent deteriorating further than its 12 percent light loss: an enormous benefit over Herschel's constantly-tarnishing speculum metal mirror. Furthermore: the modern aluminized surface would transmit a wider bandwidth of light, especially at the shorter frequencies; a tarnished speculum would quickly lose response in the bluish region of visual wavelengths, where the eye is especially sensitive using night-vision. (8) Yet, for the next several decades, Herschel's giant speculum telescopes were the world's mightiest such instruments (while being not nearly as effective as the large Dobsonians -- nicknamed "light buckets" -- owned by many amateur astronomers of our time.)
It could be said that there were three great revolutions in the fourth quarter of the 18th century: the boisterous and tumultuous ones of the United States and France; and the quieter scientific revolution wrought by Herschel, who finally made a useful instrument out of Newton's historic innovation of 1668, the reflecting telescope. King George III of England was no fan of political revolutions, but as patron of the German-born astronomer, he heartily approved of Herschel's scientific one! Yet the academic astronomical community was not particularly interested either in nebulae, or the 'cranky' and eccentric wooden and metal monstrosities that could be made functional only by an obsessive craftsman like the driven, dedicated William Herschel. Such telescopes, at first, had no influence on the practices of the 'professionals'. Herschel, undiscouraged, martialled on, quietly and diligently, dividing his time between the duties of a composer, oboist, organist, and music teacher during the day; and a lone seeker after nebulae at night, aided by his equally patient sister Caroline, who patiently transcribed his verbal descriptions. Gradually the work grew into what came to be recognized as a major research program of the highest intellectual order, and within a decade he would be lionized by the august members of Britain's Royal Society.
But in some ways, the astronomical scientists of generations after William Herschel might come to appreciate him more than his contemporaries, who perhaps did not fully appreciate the leap forward in human perception of the universe that he engendered. A nebula that had a weak, fuzzy, cometic appearance in Messier's 90-millimeter aperture refractor (9) -- perhaps only of interest to the comet-fanciers of the time -- would be seen by means of Herschel's instruments as a brilliant cluster of hundreds of tiny stellar points, almost overwhelming beautiful and arresting in the aggregate: surely an improvement of several orders of magnitude. At first the hitherto-unsuspected stars that he had prised out of dim nothingness made him suspect that all such nebulae could be thus resolved. (10) But further scrutiny with his speculum telescopes convinced him that even his instruments could not discern stellar structure in another phenomenon: what he called "extensive diffused nebulosity.'' (11)
In his paper on ''The Construction of the Heavens'', read to the Royal Society in 1811, Herschel defines nebulous matter as "those substances which give out light, whatsoever may be their nature, or of whatever different powers they may be possessed." (12) He reasons that ''faint milky nebulosities'' which cannot be resolved into stars must be deeply distant in space because of their dim and tenuous nature; the beginning and ending of their milky luminance seemed uncertain, as the objects drift slowly through the field of his telescope.
Herschel reports that from the years 1783 until 1802, he has assembled a table of 52 areas of the sky that are full of this diffused nebulosity: ''the depth or third dimension of may be far beyond the reach of our telescopes.'' He adds furthermore that such faint and extended milkiness in the skies "can only be perceived by instruments that collect a great quantity of light .'' (13)
The visual stellar limiting magnitude (by modern criteria and instruments) of the light gathering area equivalent to Herschel's mirror would be perhaps about 16th or 17th magnitude; however, since the speculum metal rapidly tarnished, his typical achievement has been estimated to be a detection of 14 to 15-1/2 stellar magnitude. (14) But the degree of his efficiency in spotting diffuse nebulosity, as remarkable as it may have seemed for the next century, was by no means a super-human accomplishment compared to the work of current amateur nebula-chasers, with their splendidly accurate modern sky catalogues, superior mirrors and lenses, enhanced optical coatings, isolating bandpass filters, and highly correcting eyepieces (which greatly enlarge the visual field, while at the same time clarifying star-points to a fineness that old, primitive gear was unable to render.)
Herschel was certainly able at least to see many of the same faint objects that may be readily photographed today by an amateur's commercial fast refractor or Schmidt-Cassegrain telescope of 6 to 8 inches' aperture, and which may be visually acquired in a 10 to 15 inch scope; but countless amateurs now pride themselves in completing visual observations of many, if not most, of his catalogued discoveries -- often with remarkably small and compact instruments that would astound Herschel. But during his time, the discoveries he made of previously unknown regions of faint milkiness (that only he could see) caused not a little skepticism. Move ahead two centuries, and it comes as no surprise at all that he can discern ''Diffused milky nebulosity'' in the general region of the brilliant belt star "Alnitak" in the constellation of Orion, plotted by Herschel as no. 25 in in his table of sites so "affected" by this mysterious glowing. For, it can be photographed in a few tens of seconds with our current technology (though it is still something of a challenge to spot by live eye in a telescope, especially anywhere near civilization and its light pollution.) (15)
Due to its massive mounting, the 40-foot telescope required a sturdy operating assistant, and set-up time was long and prohibitive, consuming many precious hours of the rare clear skies infrequently available in the cloudy English climate; so Herschel preferred using his 20-foot instrument of 18.8 inches' aperture, which could be controlled solely by himself. By mean of ropes operating pulleys and wheels, Herschel could rotate the tube in slow 12- to 14-degree sweeps of azimuth during his sky surveys.
Methodical and precise in all aspects of observing, he determined that his eyesight was most efficient when fully dark-adapted, and learned to don a black hood as a stray light shield. Proper powers of magnification were carefully chosen, Herschel explaining that ''Objects are viewed in their greatest perfection when, in penetrating space, the magnifying power is so low as only to be sufficient to show the object well...the injudicious overcharge of (inappropriately low or high power) will prove hurtful to perfect vision." (17)
As Herschel calculated that his dark-adapted pupil should admit a light cone of 0.2 inches (about 5 mm) diameter, (18) we may, by simple division of the 18.8 inch aperture of the 20-foot scope, determine that the most efficient power permitting his eye to utilize the full area of the mirror would be about 92 diameters of magnification (per King); recalculation by the present author suggests that in his f/12.8 instrument, an exit pupil of 5 mm would be obtained at a magnification of 145x, very close to the ~150x that he generally used. Modern deep-sky observers will agree that this is an excellent power for resolving globular clusters and discerning the outlines of many planetary nebulae and galaxies, while being too high for encompassing the largest nebular loops (such as the ''Veil'' in Cygnus) or closest spiral galaxies (like M31 or M33). With his two largest-aperture scopes, Herschel seldom exceeded 200 diameters' magnification during nebular studies, in order to preserve the widest field concurrent with highest contrast for picking out faintly luminous regions against the sky background.
When sweeping for nebulosities, Herschel employed a field of view that was 15 arcminutes in diameter, and found such large vistas of milkiness that "the abundance of nebulous matter diffused through such an expansion of the heavens must exceed all imagination."(20) His theories of nebular development, based on extensive observation and differentiation of types of nebulosity, led him to hypothesize that these diffuse patches represented the primitive state of nebular birth, leading eventually to the relatively defined structures of what we now call the planetary nebulae and galaxies.
He held that most nebulosity was self-luminous, was subject to gravity, and could be found in condensed or elastic form; some of the substances possessed ''the power of arresting light in its passage." (21)
It was the rich field of nebulosity and innumerable faint stars around Rho Ophiuchi that contained the suddenly-encountered dark region that so startled Herschel, who returned to it repeatedly, unable to decide from mere observation if it was an obscuring patch or a indeed a starless ''hole the Heavens.'' (22)
Herschel had previously rejected a theory that globular clusters were, in effect, glimpses of rich star fields popping into view through 'tunnels' leading outwards, through an obscuring medium. Because of the unlikelihood of finding such a multiplicity of bright holes all pointed straight at the earth, Herschel was troubled that his dark holes were also a flawed conception, but observational astronomy could offer no better explanation.
According to a paper by Dr. Elizabeth Lada, professor of astronomy at the University of Florida, William Herschel "apparently did not attach too much... significance to this... However, [his sister] Caroline appears to have guessed that this... held a potentially greater significance." A half-century later, using observations made in South Africa by her nephew John Herschel, employing the large body of data gathered by her brother William, chronicled with her invaluable assistance, Caroline Herschel compiled the first catalogue of dark nebulae (containing 33 entries, cited in a 2006 article by Dr. Michael Hoskin of Cambridge University, a scholar of Caroline Herschel's scientific work.) Dr. Lada states that "It wasn't until the early twentieth century that the work of Barnard and Wolf conclusively demonstrated that these startling vacancies in the sky were true astronomical objects -- dark obscuring nebulae -- and it took another half century until astronomers proved them to be the birth sites of all stars and planets in the galaxy, amply confirming Caroline's intuition concerning their importance in the pantheon of astronomical objects." [update from recent research, added 7/07.]
A century was to pass, after Herschel's first perplexing observation, before Edward Emerson Barnard would accumulate the evidence to persuade his fellow astronomers that these mysterious spots were not holes, but were rather actual obscuring masses of real matter. The Horsehead can surely be described as one of the most beautiful and definite of these dark tenuous bodies, and it occupies a place of honor at the very center of the investigation that follows.
Did William Herschel Discover the Horsehead Nebula?
Contrary to the premature and incorrectly researched claim of a European amateur astronomer, published about twenty years after I did the initial research that had satisfied me in answering this question in the negative: NO, he definitely DID NOT discover it. For further details, you may consult this specific 2013 updated article; I've left out his name in order to avoid any embarrassment to him, since he has now admitted (at least privately) that he was wrong. In summary: though Herschel reported finding certain dark channels in his Nebular Region No. 25, his recorded coordinates -- when converted accurately to our current system -- prove that he spotted not the smaller, faint Horsehead, south of Alnitak, but instead the 'lanes' of the larger, florid nebula to the east/northeast, now known as NGC-2024, the "Flame" nebula (discovered by Herschel in 1786.) Indeed, a modern image reveals that the nebula -- a challenge to study clearly in any but the best visual telescopes, due to the glare from Alnitak -- possesses what Herschel recorded as 'beautiful black space between nebulosities'. However, the densest of the dark zones is located about 35 arcminutes (more than half a degree, greater than the width of the Moon) from the Horsehead (as shown by this plot using the star charting program Guide 9.) So, Herschel's scans of his Nebular Region No. 25 missed turning up the existence of the Horsehead.
THE PIONEERING PICKERING
Astronomy in the middle decades of the nineteenth century was benefited by the manufacturing advances of the industrial revolution, leading to the creation of ever more perfect telescopes capable of great accuracy, far surpassing even the precision of Herschel's measurements. The Fraunhofer achromatic retractor, aided by the stability of the German equatorial mount with its sidereal tracking by means of a clock drive, ushered in nearly a century of development that would culminate in the great 40-inch aperture Yerkes refracting telescope, completed in 1897. (23)
Following the lead of Fraunhofer, the firms of Merz and Mahler (Munich), Alvan Clark (Cambridgeport, Massachusetts), Thomas Cooke (York, England) and Howard Grubb (Dublin) crafted the finest refractors of the period. The Merz and Mahler telescopes of 15-inch aperture -- one made for the Pulkowa Observatory in Russia, the other for the Observatory of Harvard -- were considered to be especially superb. (24)
The precision of these refractors, and of related instruments designed as transit devices, led them to be utilized for the careful measurement of stellar positions, as astronomy grew increasingly dominated by star counters and number crunchers. We have but to contrast Herschel's 1789 visual discovery of Uranus by means of a systematic visual search, to the theoretical, numbers-dominated work of Adams and Leverrier nearly a half- century later in the discovery of Neptune in 1846, to understand how an almost relentless application of mathematics and the scientific method had changed the orientation of astronomy.
But surpassing even the advances of the precision metal-fabricators' art, a new invention would eventually render obsolete all professional visual astronomy. As soon as photographic apparatus was sensitive enough to register first the light of the Moon in 1840, the sun's disk in 1845, and then the image of the bright star Vega in 1850, astronomers grew interested improving their results with the permanent records provided by photographs. Sir William Herschel's son John urged the Royal Society to establish a photographic program in 1855. (25) Even the conservative Astronomer-Royal Sir George Airy was impressed! The Lick Observatory's Mary Lea Shane archives contains a precious document (delicately handled in some awe by this writer): an 1851 letter from Airy eagerly inquiring about the latest technical details in stellar photography.
Though the world's greatest observatory refractor telescopes outnumbered reflectors nearly 4 to 1 in Professor Simon Newcomb's 1882 accounting in a popular book on astronomy, successful reflectors -- from Lassell's 24-inch to the Earl of Rosse's 72-inch leviathan -- offered much greater light gathering powers. (28) Furthermore, the reflector's freedom from false chromatics better aided the early astrophotographers in achieving accurate focus and clean images.
The first photograph of a nebula was made by Dr. Henry Draper in 1880, using a 51-minute exposure with an 11-inch Clark refractor. Only the central part of the great Orion nebula was registered, showing fewer stars than a 6-inch aperture telescope could reveal to the eye. The far greater efficiency of the newer ''fast'' 36-inch aperture f/5 reflector of Dr. Ainslee Common, despite its quick-to-deteriorate silvered surface and fussy, cumbersome mounting, was employed a mere three years later to secure an excellent picture of the same nebula in only 37 minutes. while recording stars invisible in the eyepiece. (27)
When Wilhelm Tempel's visual discovery of the Merope nebula in the "Pleiades" (M45) in 1859 was questioned by other visual observers, it was only through the 1885 photograph produced by the Henry brothers of France that the claim was proved conclusively. (28) Photography could unambiguously settle disputes, and advance the discovery of new objects in the sky.
THE INVENTIVE PICKERING BROTHER
In 1878 the 20-year-old William Henry Pickering would have his first exciting astronomical experience, measuring the polarization up the sun's corona during an eclipse. (29) Born on February 15, 1858, this brilliant young man from a famous Boston family would display voracious and wide-ranging scientific interests. Graduating from the Massachusetts Institute of technology in 1879, he first taught physics there while working with early experimental telephonic devices in Boston. Interest in the skies lured William away from electricity, and finally in 1887 he became Assistant Professor of Astronomy at Harvard College Observatory, where his brother Edward Charles Pickering (1846-1919) had been Director since 1876. (30)
William Henry Pickering, courtesy of Mary Lea Shane Archives of Lick Observatory
W. H. Pickering had specialized at M. I. T. in exploring the characteristics of photographic films, and in 1880 he discovered a difference in sensitivity between normal outdoor sunlight and the spectrum of indoor gaslight, leading to the development of ''indoor/outdoor'' film emulsions. In 1883, the younger Pickering published results demonstrating that photographs could be made in the infra-red light that Herschel had discovered at the turn of the century. (31)
As an avid amateur photographer, Professor Pickering produced a succession of rapid-exposure shots of a horse in motion (an idea currently very much in the air, to satisfy a $25,000 bet by Gov. Leland Stanford that a horse races at full gallop with all four legs repeatedly raised off the ground -- resolved by publication of Edweard Muybridge's famous photographs from 1878.) The clever amateur photographer Pickering independently accomplished one of the first steps that would lead eventually to the development of the 'movies'. (32)
Brother Edward C. Pickering was a tireless worker in the field of stellar photometry, and is said to have personally made over 1.5 million photometric readings. (33) In the year 1887, on the basis of William's successful photo of the Great Nebula in Orion (using a small camera lens and the new dry plates), Edward put William in charge of photographic investigations.
The Harvard College Observatory's impressive collection of nearly 500,000 plates of the sky eventually resulted from William's recommendation to his brother of pursuing a careful photographic celestial survey program. (34) In the next four years, culminating in an elaborate official report by William published 1895, extensive studies were made under the younger Pickering's direction which led to the firm establishment of many principles of astrophotography still accepted today. (35) Pickering's seminal paper contains convincing conclusions on the relative merits of reflectors and doublet lenses of various photographic focal ratios and apertures; requirements for telescope tracking clocks and guiding techniques; the limits of photographic resolutions; details of preparation of plates, development, enlarging and printing; and the enhancement of contrast for reproductions of original negatives.
In a study he called ''Quantitative Photography'' Pickering details extensive experiments on improving the standard photometric light source (being flame-driven in the days before the use of the incandescent electric bulb), methods of measuring sensitivities of plates, preventing the artifacts of ''halation'' (circular reflections around bright stars), and standardizing exposures for production of reliably comparable survey photos: all outlined with admirable precision. Of special use to his brother's program of stellar photometry is William's production of the "Standard Square", a means of securing graduated and calibrated photographic magnitudes by comparing sky photos to test plates, exposed at different increments of intensity through 1-centimer squares punched into an opaque mask.
Sky-fogging from artificial light pollution caused by gaslight and the new-fangled electric lamps is explored under varying focal ratios and exposure times. And the failure of the so-called "Law of Reciprocity" (wherein lengthy exposures deepen images at a nonlinear rate of exposure time) is examined, with a proposed "Time Correction'' of the plates. (36) This last is all the more remarkable since Abney 1894 and Schwarzschild in 1900 are considered by authorities to have confirmed "low-intensity reciprocity failure", and Pickering is not credited with his accomplishment. (37) His efforts to secure fast exposures even encompass experiments in "hypersensitizing" film by a technique now sometimes called pre-exposure, in which a brief exposure of the plate to an overall diffuse luminance increases the photographic speed of the emulsion. (38)
In contrast to his earlier experiments with the long waves of infra-red light, W. H. Pickering now explores the best techniques for photography of the "actinic rays" of short wavelengths (so named in those years after the radiation in the violet and ultraviolet part of the spectrum produced by such substances as the radioactive mineral actinium.) Careful measurements of the focal planes of Harvard instruments, at different wavelengths of light, are derived, and the ''actinic constant" -- or percentage of transmission of short-wave light -- is calculated for the reflectors and refractors employed to insure standardized exposures. (39)
The orientation of the sky's geographical coordinates on plates, the equinox chosen for measuring objects, and the sizes of star images are further standardized, (40) so that the Harvard photographic efforts may long be used to provide accurate comparative data, despite future improvements in equipment and techniques.
In this painstaking work, Professor William Pickering is assisted by the diligent E. S. King, (41) later to be renowned for his publication of "A Manual of Celestial Photography", establishing the accepted formulae for calculating the clock tracking rate adjustments to compensate for atmospheric refraction at varying declinations. King's compensations were so accurate that by 1899 he was able to use the Harvard 11-inch Draper refractor for a 2-hour unguided picture of the globular cluster M13, obtaining stellar images a mere 2 arcseconds in diameter (compared to many extant contemporary plates in which whole clusters were depicted merely as smeared blobs.) (42)
During these years of initial investigations, William's boundless energy and enthusiasm for experimenting with celestial photography under all possible conditions led his brother to send him on expeditions to test results under better skies than those available in Cambridge. First Pike's Peak in Colorado, and then ''Wilson's Peak'' near Los Angeles -- now, of course, the site of the famed Mt. Wilson Observatory -- yielded fainter images at shorter exposures, enabling the use of extremely modest apertures. (43)
William wrote in the January, 1990 edition of "The Sidereal Messenger" (a popular science magazine of the time) that his expedition to Mt. Wilson during the current winter had produced important discoveries in new photographs of the Orion nebula, made with a mere 2.6-inch aperture lens with a focal ratio of 3.3. The excellence of the sky permitted a faster lens than employed at Harvard:
"an excellent test...not of the instrument or the steadiness but of the clearness of the air, and the blackness of the sky. Owing to recent advances in stellar photography, this matter of sky illumination has assumed considerable importance, and it is very doubtful if any of the fainter nebulous extensions here described can be photographed at any Observatory located in or near a large city. This is due undoubtedly in part to the gas, but chiefly to the electric lights, which illuminate the slight haze found in the sky of nearly all localities with an almost imperceptible light, but which is nevertheless, very destructive to the fainter detail shown by our most sensitive plates when used with long eposures.''
On his Mt. Wilson photos, Pickering secured stars as faint as the 12th magnitude, as well as extensive areas of nebulosity in the constellation of Orion, streaming from the stars Theta and Zeta in the belts, with loops throughout the central area of the constellation. "This nebula is shown by three different exposures and is very distinctly marked.''(44)
The same nebula would soon be independently discovered by Edward Emerson Barnard at Lick Observatory, and would greatly influence the later investigator's future photographic exploration of the sky.
In the seminal Harvard College Observatory report on photography of 1895, W. Pickering outlines studies of the Moon and the planets, but most especially of the Orion nebula, comprising the important goal of achieving discoveries by camera that could not be detected by eye. By then over 3,000 plates had been exposed, and it had been determined that the fast f/5.5 photographic doublet of the 8-inch aperture Bache astrograph was ''especially adapted to charting, on account of its large field and scale" and would photograph nebulae as faint as those captured by a reflector. (45) Celestial photographs would now be capable of recording data of faint stars that were difficult to determine by eye by the most careful examiners: in an exposure of something less than 3 hours with the Bache doublet, stars were recorded that could be faintly seen in the renowned Harvard 15-inch refractor. (46)
Accordingly, plates of the Orion constellation contained new evidence of stars not previously catalogued, including some suspected variables, and improved images of the famed Orion nebula that could be compared to earlier drawings, as well as the photos obtained by Draper and Common only a few years earlier, to study the possibility of changes in the nebula. (47)
The resulting images would be used to produce ''isophotal'' or topographical charts of the nebula's extent, made by carefully measuring areas of differing luminosity on the original plates through a brass sheet perforated with holes the sizes of Standard Squares. That W. H. Pickering was firmly in charge of the photography project is established by his comments on P. 57, apologizing that once it had been necessary to employ a substitution plate taken in his absence, owing to an accident causing damage to the original. (48)
The Standard Squares made possible a more perfect estimate of luminosity of portions of the nebula than any visual technique had permitted; by comparing standardized plates made with different instruments, Pickering could estimate a difference of brightness of about 700 units, from the densest areas near the "fish mouth'' or ''Huygenian'' area, to the outlying tendrils faintest light.
"If the nebula be taken with a comparatively slow lens and long exposure, much greater contrasts are obtained, and the general effect is less pleasing. This is merely another illustration of the phenomenon to correct which we have applied the so-called time-correction, and it must explain the disappointment that many astronomers must have experienced when they came to examine their long exposure plates, and found so little on them not shown by shorter exposures.'' (49)
This lesson had apparently not been learned as late as 1900 by the British astrophotographer Dr. Isaac Roberts, who figures prominently in the Horsehead story (as E. E. Barnard's criticisms of Roberts' pictures will later relate.)
We turn at last to the central issued the discovery of the Horsehead nebula, and refer to the Annals of Harvard College Observatory published in 1890. Each new plate -- taken by W. H. Pickering and his assistants E. S. King, Robert Black, and A. E. Douglass (50) -- was breaking new astronomical ground, as the Observatory's announcements of discoveries would reveal. A staff project was undertaken: carefully measuring and cataloging all the newly revealed stars and objects, with the same methodical skill as demonstrated by the professor's work at the telescopes and cameras, requiring an extensive program of plotting and enumerating to be carried out as each plate was secured. (51)
Popular and respected modern astronomical reference works -- such as "Burnham's Celestial Handbook" (52), written by a staff member at Lowell Observatory (a comprehensive work often cited by many other volumes and articles) -- fail to give W. H. Pickering his due credit for producing the first photographs of the Horsehead nebula, and the present author presumes to suggest why. The paper announcing the discovery of what we now call the Horsehead, ''Detection of New Nebulae by Photography'' is included in the Annals of Harvard College Observatory, Volume 18. It is presented without attribution in the publication, edited by Edward C. Pickering, the director. The unidentified author refers to his previously published discussion of the advantages of the wide field doublet, establishing conclusively that it has been written by the photographic expert, brother William. Furthermore, the younger Pickerings's assertive, fluid, and detailed style is clearly present throughout; indeed, the famous British astronomer E. Walter Maunder credits the paper to W. H. Pickering in the Journal of the British astronomical Association, Volume I, published in 1891. (53)
W. H. P. himself covers exactly the same ground in his later signed paper that comprises the entirety of the Annals of Harvard College Observatory for 1895, quoted extensively in paragraphs above.
We come now to a most remarkable and unexpected episode in the saga. The Orion nebula plates taken by Pickering with the Bache telescope were given to a staff member, one Mrs. Williamina Paton Fleming, for her examination, categorization, measurements, and cataloging of stars and objects.
Williamina P. Fleming, courtesy of Harvard College Observatory
According to Dr. Martha L. Hazen, the Curator of Historical Photographs at the Harvard College Observatory, Mrs. Fleming (1857-1911) came to Massachusetts from her native Scotland in 1878 and went to work early the following year in the household of Dr. Edward C. Pickering -- as his second maid! Impressed with her accuracy and persistence, Director Pickering hired Mrs. Fleming to work part-time at the Observatory in 1879, and from 1881 until the year of her death she was a staff member, (54) a very good example of one of the early unsung women in the male-dominated world of astronomy. Her portrait reveals an extraordinarily determined countenance, even for those formal times! In another photograph Mrs. Fleming is shown sternly supervising the women "computers" at the Harvard Observatory, with Director E. C. Pickering looking on (perhaps with the trace of a patient, fatherly smile on his countenance.)
Beginning on June 27, 1888, (55) Mrs. Fleming took each of the Orion plates, placed it on an illuminated frame at an angle of 45 degrees, and studied all portions with a magnifying glass to find any suspected nebulae recorded during the exposure. Measurements were made of the coordinates of each object, referred to the star chart of the standard Bonner Durchmusterung reference published in 1863, plotted at the same scale as the new Harvard photographs. In the HCO Annals publication a table is given comparing the results of searching through four plates, covering the area, with a fifth plate used to check the results of the others. The "A" rating given to the Zeta Orionis nebula qualified as 'unmistakable' on all the plates taken of the region. (56)
Director E. C. Pickering, with Williamina P. Fleming (center) supervising the "women computers" at HCO. Evelyn Leland seated (front); Antonia Maury at left. Courtesy of Harvard College Observatory Archives
The official discovery plate that registered the Horsehead nebula was number B2312, taken with the Bache telescope in Cambridge on February 6, 1888, with an exposure time of 90 minutes. (57) The HCO logbooks are now online (2012); the cover for Series B is seen here, with the individual pages for the dates February 3 and 6, 1888, visible here; the entry for 2312 is very brief, indicating the area (in right ascension) covered by the plate, and that the sidereal clock rate was employed.
By setting up the star chart program 'TheSky' Version 6 for the coordinates of Cambridge and the date of that exposure, the author determined that the star Alnitak, and the nebulae in close proximity, would have transited not long past midnight.
HCO director E. C. Pickering reported the results of the examination and measurements made on this plate by 'Mrs. M. Fleming' (using initial "M" for his preferred diminutive "Mina") in his 1890 paper "Detection of New Nebulae by Photography"; here (below) he describes the careful method of Williamina Fleming in her examination of the negatives to make discoveries of new objects therein:
On B2312, Mrs. Fleming recorded a nebulosity -- listed as No. 21 in her table -- described as follows (bold emphasis added by the present author, to signify the Horsehead's dark cloud): "A large nebulosity extending nearly south from Zeta Orionis for about 60 minutes. More intense and well marked on the following side, with a semicircular indentation 5 minutes in diameter 30 minutes south of Zeta. Good plates of this region show this object, and it has been used here as a test for some time..."(58)
In referring to "this object", it is evident that Pickering means the large 60-minute nebula and not specifically the "semicircular indentation".
The "large nebula" extending south of Zeta was reported by Edward Pickering to Dr. Dreyer for inclusion in his successor to the NGC, the Index Catalogue of 1895; Dreyer's list was ordered by right ascension and thus the object was numerated "IC-434" in the Dreyer's (first) Index Catalogue. The Horsehead nebula, of course, is the "semicircular indentation 5 minutes in diameter" and, as it was described by Mrs. Fleming in Pickering's paper as a detail of nebula no. 434, it was not cited as a separate object at that time, and not included in the IC (indeed, it was not given a 'catalogue number' specifically until Edward Barnard cited it in his 1919 published list of dark markings: no. 33, on the page shown here.)
The British astronomer and compiler "references" Harvard's new nebulae to "Pickering" on the second introductory page, and again, in the individual nebula entries, to HCO's director--not as Pickering had specifically stipulated, to Fleming. Numerous articles consulted by this paper's author, analyzing historic contributions to astronomy by women, have reported what is obviously a consensus view: that it was formerly conventional practice to diminish 'underlings' and attribute their work to their ultimate superiors. Furthermore, women were at a special disadvantage in this era of science: as researcher Steven H. Yaskell observes in his 2005 article "Henrietta Swann Leavitt, the star catcher", included on this web page:
...women did more than replace the largely young male "computers" who performed the routine computations for the daily observations and measurements (and who suffered similar career dead-ends like their female counterparts, and in some cases worse). Some in England became full partners with the hired male staff... The same was true for the woman computers at the Harvard College Observatory. But any sense of a shared social status was missing. Some archives and the inevitable anecdotes suggest that it was very much a "child - to - father" relationship between the women computers and the regular male staff, and particularly, with the director.
However, all analysis of Edward Pickering's attitude and behavior to his 'female underlings' shows that he stood apart from the male- authority- figure- dominated attitudes of his time. In the words of Dr. Gina Hamilton, (University of Southern Maine), "While Pickering published in his own name, he freely gave credit to his researchers...Among the many famous women who worked with Pickering at Harvard were Williamina Fleming (c 1881), who began work on an empirical classification system of spectral types in stars. While engaged in this monumental task, she discovered ten novae, more than three hundred variable stars, and some sixty new nebulae...Fleming's classification system was further refined by Annie Jump Cannon." (see her paper, Innovators or Interpreters? The Historic Role of Women in Science).
A further accounting of Nebulae discovered at the Harvard College Observatory by E. C. Pickering (HCO Annals, Volume 60, 1908) confirms the progressive and collegial attitude of the Observatory's Director. In the table on p. 149 -- online here -- entry No. 62 lists nebula 434 as having been discovered by "W. P. Fleming". We have truncated items 19 through 55 in order to show the relevant section of the page, below:
So, as far as the Harvard College Observatory is concerned, the official discoverer of the nebulosity containing the Horsehead was a woman, and one who been promoted from housemaid to observatory staff member! And now we are pleased to present the first modern publication (which we put online originally in 2005 in cooperation with the late Dr. Martha Hazen of Harvard College Observatory), the historic 1888 image of IC-434 and the Horsehead:
Zeta Orionis & Nebular Region: from Plate B2312, W. H. Pickering's early photographic program at Harvard College Observatory, 1888 - Harvard College Historical Photographic Archives Collection: by permission, and courtesy of Dr. Martha Hazen. You may see a larger area digital scan of the Orion belt region from this same plate by clicking here.
The conclusion to the earlier 1890 Harvard paper by E. C. Pickering states that "fourteen of these objects are contained in Dreyer's Catalogue" but "Twelve [nebulae] detected by the photographs are probably new"; they had not been included in Dreyer's New General Catalogue, published in 1887. Since only 1/4000th of the sky was covered by these plates, the proportions of known nebulae were correct ''we might expect to discover four or five thousand such objects by photographing the entire sky." (60) This of course was a considerable understatement! Within half a decade, James Keeler at Lick Observatory, using a 36 inch reflector telescope for photography, estimated in an 1899 paper that "thousands" of "unrecorded nebulae are within reach of our 36-inch reflector... the number of the new nebulae in the whole sky would be about 120,000" if he was correct in predicting about 3 new nebulae in each square degree of sky ('nebulae', in the conventional usage of the time, included not only diffuse gaseous objects, but also galaxies.)
Such a project -- Pickering's suggestion to photograph as much of the entire sky as possible -- was of course undertaken, by parallel investigations, and the 1890 Harvard paper's prediction proved to fall far short of the mark, judging from the results that were obtained only a few years later with the great Crossley Reflector at the Lick observatory by Keeler, and later in the 20th century by Heber D. Curtis!
In the 1895 Harvard College Observatory Annals, Edward's brother William Pickering elaborates on the nebulae discovered on these plates taken from Cambridge. A copy of Plate B2312 is published, and he states that lantern slides of it were widely distributed just after was made February of 1888. The Orion belt stars Iota and Theta are found to be connected --
"...by a long nebulous streak, and another nebula, that surrounding C Orionis, is shown at the top of the figure...near the top of the figure, two of the stars of the belt, Zeta and Epsilon, are shown, the former partially enveloped in a large nebulous mass [NGC 2024] clearly visible on the east, and to which is attached a streamer extending towards the great Nebula. In this streamer is a well-defined and rather striking notch [the "Horsehead" - our italics]... In the figures so far described, are shown nebulous masses of which a large part, more or less imperfect, can in each case be seen visually." (61)
W. Pickering finds that unlike the great Nebula in Orion with its deep incurving branches, well developed on the inside but vague at the outer extremities, ''when we come to the nebula surrounding the star Zeta Orionis we find matters reversed, and the notched side is turned away from Theta indicating another and stronger outside influence." (62)
Later, Professor W. H. Pickering reports examining the Bache plates to compare nebulosities shown on his Mt. Wilson photos, and finds that since the new negatives registered stars 3 magnitudes dimmer, stars of the 14th and 15th magnitudes are distributed rather unevenly throughout the region. ''Whether the fainter stars are really absent in this region, or whether their light is absorbed by non-luminous gas, it is of course impossible to tell.'' (63)
As chronicled in greater detail above:
• All of the objects confirmed by the team are sent by Dr. E. C. Pickering to the famed Dr. J. L. E. Dreyer, compiler of the New General Catalogue, published 1887 and containing all the nebulae known to the end of that year.
• Dr. Dreyer lists Mrs.Fleming's large 60-minute notched nebulosity as "No. 434" his updated ''Index Catalogue" and presents his new collection of nebulae, incorporating the Harvard findings plus those of ten other individuals and observatories, to the British Royal Astronomical Society.
• To further muddle the issue of the discovery of IC 434, Dr. Dreyer catalogues the object not with Mrs. Fleming's name -- the good lady being at the time unknown to most of the world's celebrated astronomers -- but lists under the co1umn of observers for all of Harvard's objects -- confusingly -- simply ''Pickering.'' (Thus, one eminence in Europe pays tribute to another one in America.) A literal reading of this by later historians -- often amateurs -- results in the confusion, in some works, of the two Pickering brothers, Edward and William--so the Horsehead 'discovery' is often attributed to one, or the other: in both cases, precisely incorrect.
• The following day Dreyer addresses the Royal Astronomical Society, explaining the new entries to his ''Index Catalogue of Nebulae'' with the perhaps apologetic dismissal that most are "very faint and minute and doubtless represent but a very small part of the innumerable host of similar objects which are within the reach of our largest telescopes... the majority these new nebulae cannot compare in interest with those catalogued in earlier years...the number of observers to whom this will be of use will naturally be a comparatively limited one." (65)
Little could the good Doctor guess that the study of astronomy would soon turn from the rather arid territory of calculating and infinitely refining stellar positions, to the fruitful field of measuring the entire extent and substance of our universe by means of these insignificant, often spiral-shape, smudges! We must credit Dreyer with realizing that the "extensive and diffused nebulosities detected by means of photography by Mr. Barnard and Professor Max Wolf" were, after all, important: they could corroborate the great visual work of Sir William Herschel.
Dreyer continues, ''The fifty-two regions found by William Herschel to be more or less 'affected with nebulosity' ought to be reexamined by means of photography.''(66) And that is precisely what the amateur astrophotographer Isaac Roberts, a future participant in the Horsehead race, was currently doing with his 20-inch aperture reflecting telescope in the Sussex inlands.
We can summarize the results of the Harvard Observatory's photographic program, at least with respect to the Horsehead nebula findings up to 1895, and later in 1908, as follows:
1. W. H. Pickering persuades his elder brother E. C., the HCO Director, to undertake a systematic study of celestial photography, and to begin a sky survey.
2. The younger Pickering explores virtually all concepts of astrophotography, and perfects possible techniques to aid his brother's photometric program and to discover new objects within the grasp of Harvard's equipment. His examination of the craft represents the absolute state-of-the-art of celestial photography in the late 1880s, describing some techniques that are still currently employed.
3. The Orion nebula is chosen for special study, and a series of plates is undertaken, starting in 1887, expanding on test photographs of the region earlier made by W. H. Pickering. Nebulous regions are shown on early test plates, and a curious streamer south of Zeta Orionis (but not the Horsehead) is rather casually noticed, and is communicated by letter to the 1887 Astrophotographic Congress. By early 1888, over 3,000 sky plates have been made by Harvard College Observatory.
4. On February 6, 1888, an especially good plate of Orion, No. B2312, is taken by Pickering, and lantern slides are distributed to the public.
5. Four months after production by W. H. Pickering of this fateful discovery plate containing the Horsehead, Mrs. Fleming begins the serious task of cataloging the new objects found on the Harvard plates. The nebula south of Zeta, containing the ''notch'' we now call the Horsehead, is catalogued on June 27, 1888, with Harvard's official publication listing W. P. Fleming as ''discoverer.'' (87)
6. E. C. Pickering sends the official findings of new nebulae to Dr. Dreyer, who presents his Index Catalogue, containing Harvard's nebula No. 434, to the Royal astronomical Society. Dreyer publishes the IC 434 nebula discovery, crediting ''Pickering'' -- not his employee Mrs. 'Mina' Fleming -- as ''observer."
7. W. H. Pickering's own report on Harvard's photographic investigations is published in the HCO Annals, containing his procedures and comments. Of the ''nebular streak'' that comprises IC 434, he makes special note of the striking "notch", believed at the time to be an indentation in the stream of luminous matter. He hypothesizes that, owing to the noticeably irregular distribution of the faintest stars in the area, ''non-luminous'' masses may be present. Thus, the prescient Pickering makes an early and valuable observation about a phenomenon to become critically interesting to 20th and 21st- century astrophysicists: dark non-luminous molecular matter.
8. In 1908 Dr. Edward Pickering once again publishes a list of Harvard nebula discoveries, now updated: he indeed repeats his credit -- now stated even more explicitly -- to Mrs. Fleming as being the discoverer of IC-434. Of course, he had also cited her specific discovery and description of the Horsehead back in 1888: her observation of the "semicircular indentation 5 minutes in diameter" seen as a detail of the long nebula south of Zeta Orionis. QED: Fleming discovered the Horsehead!
Most of the events described above were pieced together chronologically by the present author from documents in the Lick Observatory Mary Lea Shane Archives, and from the magnificent UC/Lick Observatory astronomical library in Santa Cruz (comprising the great works on astronomy that the Observatory's first director, Professor E. S. Holden, and his successors collected since the founding of the observatory in the latter part of the 19th century.)
As the present author worked his way from one document to the next, his anticipation mounted as the story began to unfold. A great moment was at hand when he asked by phone for Dr. Martha Hazen, the Harvard College Observatory archivist, to look for the historic plate No. B2312.
After only a brief moment, Dr. Hazen pulled the plate from its place in the neatly-catalogued Harvard files. The jacket had apparently been replaced since 1888, and was later labelled with words to the effect that was an ''Historic Plate - Contains the Horsehead.'' It was Dr. Hazen's impression, upon drawing the plate from its envelope, that the Horsehead region stood out dramatically on the plate, and that it could have been spotted as soon as the photograph had been developed.(68)
Sad to say, the only copy available to the present author, at the time of the first internet publication, was merely a cruder photocopy of the 8x10 print sent to him from Harvard by Dr. Hazen; the positive print being rather dim, the author had it enhanced by the Lick Observatory photographic department, and then had it converted into a half-tone for expected publication in ASTRONOMY magazine. That material still resides somewhere in the bowels of Kalmbach Publishing Company's storage vaults and has failed to materialize by the time of the preparation of this web page; so we at first presented, in 2005, a rather inferior photocopy of that processed image, which you may see by clicking here. However, we also made a direct slide of the enhanced pre-half-tone photo print done by Lick Observatory, which was used by us in presentation of talks to numerous local astronomical organizations (and the Lick Observatory astronomy department); that slide was sent back to Dr. Hazen with our gratitude, and she showed it, and other slides the author prepared, in her joint Waldee-Hazen paper and talk on the photographic discovery of the Horsehead at the convention of the Astronomical Society of the Pacific in Cambridge in late 1990. It was not until 2010 that we managed to make the improved reprocessing of the original plate as shown above.
Despite the passage of a century, the presence of a few photographic defects such as the bright halation rings around stars, and a few smudges, the beauty of the constellation was well-captured in the original, surprisingly fine plate, showing the elaborate tree-like aureole of NGC 2024, the fuzzy star NGC 2023, the softly undulating luminance of IC 434, and of course the dark protruding ''bay'' (as it came to be known early in the next century.)
The astronomical world would hear much more from "Mina" Fleming before the end of her distinguished career; but sadly the Horsehead was, at the time of her death -- far too young at merely 54, from long term complications leading to fatal pneumonia on May 21, 1911 -- still a nearly complete obscurity and mystery, and as its significance was unappreciated, her involvement in its discovery had long been forgotten. None of her subsequent nebula discoveries from Harvard plates would bear quite the cachet, a century later, of the now iconic dark nebula (though, of course, it was Barnard who specialized in such things and gave it his particular attention--and surely helped eventually to make it famous.) Her life was crowned with many scientific successes and public acknowledgments, a crater on the Moon being named in her honor (perhaps at the time thought to be a very significant veneration.) One would like to think, however, that recognizing her sharp-eyed first comprehension of the detail of the Horsehead, as a symbol of a woman's contribution to science when nearly every pressure was put to bear to keep her in an appropriate 'humble' station, might be an even more celebrated reward.
Nevertheless, her obituary in the Monthly Notices of the Royal Astronomical Society, Vol. 72 (Feb. 1912) reveals the pride of England in honoring a Scotswoman by birth, one of the merely five women that had been, at the time, elected to (honorary) membership of the society. It is a touching notice, and one which shows she had indeed earned respect, and appreciation. But a far more valuable eulogy was composed by her Harvard colleague Annie Cannon, who contributed an article spanning four pages (not quite all posted online) in the Astrophysical Journal, V. 34, which contains a finely reproduced signed photograph, and a succinct summary of her recognized work: besides organizing, devising, and systematizing the method of studying Harvard's plates, with greater responsibilities than formerly as a "copyist and computer", she undertook "the first general photographic classification of stellar spectra," with her measurements of 10,351 stars; the "discovery of ten Novae" and more than 300 variable stars. Fleming discovered "fifty-nine gaseous nebulae" -- [let's just add the Horsehead and make it an even 60!] -- ninety-one stars of the fifth type, Class O, and sixty-nine stars of the Orion type having bright hydrogen lines... she became interested in the red stars, whose spectra are of the fourth type, Class N...[and] assigned to a new type called... Class R" other stars with spectra "in the region between Hβ and Hγ" [see Star classification]; as such, Fleming stood well above many established male astronomers of the era, as a scientist informed in, and practicing, the current cutting-edge research in stellar astrophysics.
After a very brief but poignant account of her late infirmities, Cannon concludes with some charming remarks -- which may seem very quaint by the socio-gender standards of today -- about the astronomer as a human being: "possessed of an extremely magnetic personality and an attractive countenance, enlivened by remarkably bright eyes... Fond of people and excitement, there was no more enthusiastic spectator in the stadium for the football games, no more ardent champion of the Harvard eleven. Industrious by nature, she was seldom idle... As much at home with the needle as with the magnifying eyepiece, she could make a dainty bag, exquisitely sewed, or dress a doll in complete Scotch Highland costume. She was never too tired to welcome her friends at her home or at the observatory, with that quality of human sympathy which is sometimes lacking among women engaged in scientific pursuits."
Thre are numerous rather compressed online summaries of her life-work -- though no full length biography -- but none that I've consulted seems to parallel the depth of understanding, friendship, and sensitivity that are found in Cannon's simpatico reminiscence, tinged with a sense of irreparable loss.
Remarkably, Harvard has digitized her journals from 1900, written as the newly appointed Curator of Astronomical Photographs, here.
The present author has posted discussions of a few of the 43 IC nebulae discovered by Mrs. Fleming, and his visual observations: click for IC-4593, IC-420, IC-1747, and IC-428 (in an article covering also numerous other nebulae observed on the same occasion.) Harvard also published, and the IC listed, 'discoveries' by Fleming of a few items that had been detected by earlier observers; here are our reports on two of them: IC-4997, and IC-4406.
William Pickering's Later Photographic and Astronomical Activities
This chapter should conclude with some further notes about William Pickering. The distinguished scientist took his considerable skills and Harvard's equipment -- and irascible, contentious personality! -- to Peru and finally Jamaica, establishing an observatory he would occupy, essentially by himself, for the rest of his years. Along the way, he mounted the 24-inch Alvan Clark refractor that Percival Lowell had purchased for his own Flagstaff Observatory, and turned from photographic pursuits back to the techniques of visual observing. Yet, his greatest discovery was made in 1899 by the photographic process, when he found the ninth satellite of Saturn, which he named Phoebe, on plates taken at Harvard's observing station in Peru.
The "Mars mania'' of the era, stimulated by much talk of Professor Schiaparelli's canals, found W. H. Pickering a central participant. Visual examination of the evanescent surface markings were interpreted by the Harvard astronomer as clear evidence of the presence of water, and even large tracts of vegetation. (70) Lowell appropriated many of Pickering's ideas, and developed them into outlandish theories of huge, scientifically sophisticated Martians, cultivating their arid soil with what precious fluid they could drain from the polar ice caps. (71)
Pickering's next fascination was the earth's satellite, and his monumental photographic volume "The Moon" was published in 1903. Unable to restrain his creative imagination (in contrast to the soberer Edward Barnard and other cautious observers of the era), Pickering was quick to interpret his sightings of so-called 'transient lunar phenomena' as certain evidence of a tenuous atmosphere, water vapor, snow or hoar-frost, even organic life: something resembling vegetation was seen "coming up, flourishing, and dying, just as vegetation springs and withers on the Earth." He concluded that there were undoubtedly "real, living changes--changes that cannot be explained by shifting shadows or varying vibrations of the lunar surface." (72)
Through it all, conservative academic astronomers sometimes huffed in displeasure, as William's early scientific luster (achieved while working under the sober supervision of his brother) slowly eroded. Astronomers fortunate enough to employ instruments more powerful and accurate than those of Pickering were skeptical of the increasingly 'pseudo-scientific' extrapolations made, based on shivery views with small scopes. An example is found in the great Martian ''canal'' dispute: though Pickering, Lowell, and Douglass (not to mention Schiaparelli and many others) discerned glimpses or "revelation peeps" (73) of sharp linear markings, Barnard at Lick Observatory could resolve the Martian "lines" into myriads of detached dots and mottled patches with the superb 36-inch refractor, determining that the optical artifacts that 'meant something' to the eager promoters of alleged Martian vegetation and civilization were spurious--the present author was thrilled to hold and examine Barnard's own private drawings done at the great Mt. Hamilton instrument, sent to his mentor Simon Newcomb but not published in public at the time, as Barnard was loathe to be drawn into the controversy with Lowell and Pickering. (74)
Ironically, after his Harvard College Observatory photographic program was well underway, W. H. Pickering seemed to stray from reasoned scientific pursuits into the dangerous matters of subjectivity, vowing that ''the human eye must reign supreme." (75) From our vantage point at the end of another century [written in 1990], Pickering's hair-splittings on the questionable evidence obtained from fleeting glimpses with small telescopes seem as outdated and contentious as certain medieval theological arguments.
Isolated in his Jamaican retreat and venerated as the great ''Professor'' by the locals, he grew somewhat preachy in advising the younger astronomical community. Sternly recommending that since the Lick 36-inch refractor was apparently incapable of showing the 'detail' that Pickering believed he could accurately see and describe using relatively tiny scopes, the mighty Mt. Hamilton instrument should be modified by the addition of ventilating blowers to improve the definition of details on Mars, moralizing, "It would seem almost a duty to try it." (76) Indeed, a modern analogy to Pickering's endless strivings for perfection in visual observation (whose accuracy is always compromised by the distorting blanket of earth's atmosphere) may be witnessed in the frequently irreconcilable arguments in the so-called "underground" audiophile review magazines [or, later as we would come to observe, on Usenet!]
Finally, the Professor's arrogance led the Harvard College Observatory' new director, Harlow Shapley, to demand the return of their venerable Draper refractor to Cambridge; Pickering himself would finally be retired in 1924, though he maintained the Jamaican observatory out of his own pocket. (77)
It seems sad to see such a youthful pioneering mind retreating into old-fogeyism, almost forgetting the leap of scientific advancement that he had engendered by espousing astrophotography. Philip N. Sadler, of the Harvard-Smithsonian Center for Astrophysics, chronicles the last great fixation of his career: a decades-long search for a trans-Neptunian planet. Now an elderly man who "did not believe the automobile was here to stay'' and who chose to ride a horse instead, (78) Pickering barraged the press with quixotic predictions of a planet beyond Neptune, starting a short time after Percival Lowell, his old friend turned nemesis, had commenced a photographic search.
Working without assistance in Jamaica, and without the benefit of the kind of simple and convenient equipment that even today's amateurs can use with relatively little effort, Pickering concentrated on a ''simple graphical process'' to utilize perturbations Uranus' orbit, following the success of Adams and Leverrier in predicting Neptune's existence in 1846. Sadler reports that Pickering chose to avoid computation by drawing a predicted perturbed sinusoidal shift in Uranus' orbit upon a glass plate, superimposing it on the actual ephemeris. By shifting around the glass, he felt he could find the ''hairpin turn'' in the planet's travels that would indicate the presence of an unknown perturbing body.
Sadler's analysis of Pickering's work concludes that ''his successive curve fitting actually made the data worse. His 'ink upon glass' method was so subjective that it could produce virtually any curve." And by ignoring observational or computational errors, Pickering's method was fatally flawed: he was ''in effect engaged in a hopeless task." (79) Nevertheless, William Pickering published by 1930 ''seven different predictions of planets ranging in distance from 5.7 AU to 6.250 AU from the Sun and having masses of 1/20 to 20,000 times that of the Earth." (80) Crackpot stuff, and perhaps pseudoscience: sad indeed.
The final irony is that after the trans-Neptunian planet Pluto was discovered by Tombaugh on plates taken at the Lowell Observatory in 1930, the astronomers Seth Nicholson and Nicholas Mayall went back and re-examined some search plates taken at Mt. Wilson in 1919 at the encouragement of Pickering, who had named his current prediction ''Planet O".
In 1919 these plates yielded no trans-Neptunian planet, but when checked again, Pluto was indeed found on them, only 3.6 degrees in declination from Pickering's position. (82) With his crude empirical curve-fitting, Pickering at least in some respects had bested the sophisticated and rigorous mathematical procedure of Lowell by correctly predicting that ''Planet O" would spent part of its orbit inside that of Neptune; predictions of the photographic magnitude, longitude of the ascending node of the orbit, and inclination to the ecliptic were quite reasonably close to accepted modern values for Pluto. (83) In the end, Pickering was philosophical. When he learned that Percival Lowell's initials PL would be used as the symbol for the new planet Pluto, the professor remarked, ''That's a good name, 'Pickering-Lowell.'' (84) After a long and productive life, the 80 year old astronomical gadfly died in 1938, opinionated and vigorous to the end--but now, mostly forgotten.
Had the Mt. Wilson plates been scrutinized more carefully at first, professor W. H. Pickering would have been credited the successful prediction of the existence and the subsequent discovery of Pluto (at least until the critics had assessed his methods.) We at least owe him recognition for the expertise that led to the photographic discovery of the Horsehead nebula--and the immediate, sensible speculation that it was likely an opaque obscuring body, a fact that would not be established for another quarter of a century until Edward Barnard focused his considerable skills as photographer and observer on the perplexing 'dark marking'.
THE GERMAN WHO DISCOVERS NORTH AMERICA.
The world of science and engineering is replete with episodes of coincidence each time a new technology arises. Yet the streamlining process of simplifying historical perspective prefers to paint sharp contours around delicate shades of gray. We confidently confer the title of ''discoverer'' or ''developer'' upon Bell for his telephone without recalling the accomplishments of Reis or Berliner. Sir William Herschel may have provided the broad shoulders of support for all the participants in the early studies of nebulosity, but it is the technical perfection of photography more than the ingenuity of any one astronomer that guaranteed the inevitable results.
Two figures are linked by historical coincidence in the running of the Horsehead derby. Contemporaries of similar interests and insights, they indeed could almost be defined by each other, their successive chapters entitled, "Wolf: The Barnard of Germany" and "Barnard, the Wolf of America". In order of contribution the first of the pair is Dr. Maximilian Franz Joseph Cornelius Wolf (whose aristocratic name betokens a man in as high social station as Barnard was humble.)
Dr. Max Wolf, from the private collection of Prof. E. S. Holden, courtesy of the Mary Lea Shane Archives of Lick Observatory
Born on June 21, 1863 in Heidelberg, Max Wolf differed in one crucial respect from his American counterpart Edward Emerson Barnard: Wolf was not an impoverished, fatherless, self-made youth out of a rustic environment, but the well-reared son of a wealthy physician, a prominent citizen of the seat of an ancient university. But the astronomical careers of Wolf and Barnard had many parallels: as teenagers both acquired their first telescopes, and both obtained their bachelor's degrees in mathematics but one year apart. (90) Wolf discovered an important periodical comet in 1884, while by that same year Barnard had found his third such object.(91) Wolf achieved the photographic recovery of Halley's comet on September 11, 1909; Barnard made virtually the last visual observation of Halley during its then-current period on May 23, 1911. (92) Both astronomers were distinguished astrophotographers and made many discoveries by camera; each was credited by authors of differing national bias with the earliest detection of vast structure in the Milky Way, and the revelation of many of the sky's dark nebulae. (93)
While Barnard in California was employing a six-inch aperture, short focal-length camera lens to produce widefield survey plates of the Milky Way, Wolf in Germany was employing portrait lenses of four and five-inch apertures to cover the same areas of the sky. Pictures of the instruments reveal a remarkable technical similarity: an 1898 engraving of the Heidelberg asteroid search telescope reminds one of Barnard's Lick Observatory Crocker telescope with the Willard lens in virtually all respects, save only that Wolf had mounted a second short-focus camera for producing stereo-comparator plates. (94) The photographic results betoken a good match of the astronomers' technical skills, but Barnard was the harder worker of the two, enduring long nights alone in frigid domes without the assistants that Observatory Director Wolf could employ to spell him from the drudgery of astro-guiding for many a long hour. (95)
The wealthy American science benefactress Miss Catherine Bruce was to provide the funds for photographic telescopes in both Europe and America that would be used to great effect by Wolf and Barnard: a 16-inch aperture doublet graced the facilities of the Heidelberg University Observatory and produced many asteroid discovery plates, while the 10-inch Bruce Telescope presented to the Yerkes Observatory was employed at Williams Bay (and for one year it Mt. Wilson) by Barnard, producing his finest photographs of the Milky Way and dark nebulae. (96)
Gerrit Verschuur in his book "Interstellar Matters" claims that ''neither man referred to the other's work, perhaps not surprising considering that communication was very slow at best" (97) but in truth -- as the present author discovered from copious evidence in the Lick archives -- Barnard graciously extends the credit for the first photograph of the great nebula north of Alpha Cygni to Wolf, writing in a 1903 article that it "was first photographed by Dr. Max Wolf some twelve years ago and has been called by him the 'American Nebula' from its striking resemblance to North America as shown on maps and globes." In a footnote, Barnard continues, "The 'North America Nebula' would perhaps be more definite, for it is North America to which Dr. Wolf intends the compliment." (93) Wolf in turn confirms "the great nebula discovered by Mr. Barnard in the cluster G. C. 1420 in Monoceros" in his account of various nebular photographs taken up to the year 1891. (99)
Both Wolf and Barnard were frequent contributors to the German publication Astronomische Nachrichten, a leading professional journal found in the libraries of all the great observatories, so despite Verschuur's assertion, the major discoveries of these two skilled observers should have been well known to each other and to the entire astronomical world, at least within a year or two of the appearance of their articles. And Barnard, humble man with merely a bachelor's degree in mathematics, was familiar with the social protocols of 19th century science, and an astute observer of same -- at least until his notorious contest of wills with his boss at Mt. Hamilton, Professor Holden! Barnard would, at that time, have been the last person in professional astronomy to willfully dismiss or ignore a much more famous colleague.
In 1903, the same year of Barnard's previously quoted comments about Wolf, the German concludes from studies of deep exposures of the constellations Cygnus and Orion that areas of the richest extended nebulosity are accompanied by "regions nearly void of faint stars" (100), echoing the remarks of W. H. Pickering in his 1895 Harvard College Observatory paper. (101) The photographs taken in Cambridge led the Harvard astronomer to report the possible existence of light-attenuating non-luminous gases, but there Pickering dropped the issue. Wolf, like Barnard, was deeply impressed by the voids or 'heavenly holes' and asserts that ''all extended nebulae are situated in the interior of regions containing only a very small number of faint stars...My assistant, Mr. Kopff, has published an exact enumeration of the stars about these objects, from which it is proved that nearly all faint stars have disappeared from the immediate surroundings of these nebulae, though they are ten times more numerous both in the nebulae themselves and far outside." (102)
While it is not strictly true as Wolf states that "all extended nebulae" are surrounded by areas lacking the dimmer stars, he is on the right track when questioning, "Is there a dark mass following the path of the nebula absorbing the light of the fainter stars?" (103) A dozen years earlier, Dr. Wolf's interpretation of dark markings in the sky is more conventional, following along Herschel's lines of reasoning about "holes". In Volume 127 of the Astronomische Nachrichten, covering submissions from 1891, Wolf publishes his report "On the Great Nebula around Zeta Orionis'', imparting news of his discovery that
"The star Zeta Orionis is surrounded by an extraordinary expansive nebular mass, photographed in six different exposures taken with three different photographic objectives, the first preserving the image on December 12, 1890."
The region to be later catalogued by Dreyer as IC 434 is described by Wolf as ''broken by an oval bay." (Waldee's translations) (104) Thus, Dr. Wolf -- like W. Pickering, Dr. Isaac Roberts, Heber Curtis, and most other early Horsehead commentators -- considers the dark region to be a feature of the nebular streak IC 434 and not a superimposed opaque body. The present author is sad to state that he searched Wolf's articles in vain for description of a ''pferdkopf'' (horsehead).
In the Journal of the British Astronomical Association, Wolf submits from Heidelberg on February 17, 1891 a "Note on a Nebula surrounding Zeta Orionis discovered by Photography", summarizing his own independent conclusions on the proper techniques for capturing extended nebulosity, as opposed to the point sources of starlight.
"A year ago I photographed the Pleiades with a 2-1/2 inches aplanatic lens by Steinheil, and I was surprised to obtain, with an exposure of one hour, all the nebulae which the MM. Henry obtained only with an exposure of several hours, using a large telescope of 13 inches aperture.
"If considered more carefully, this result was to be expected, as an example will show. Let us compare the 20 inches reflector of Mr. Roberts, having a focus of 100 inches, with an ordinary portrait lens of 4 inches aperture and 12 inches focus.
"In photographing the fixed stars the intensity of the image depends only on the area of the lens used. In this respect the Roberts telescope, ceteris paribus, would be 25 times superior to the portrait lens...But it is a quite different thing with objects which show a finite area, as nebulae, comets, &c...Therefore it is not only cheaper to use ordinary photographic lenses, but they are also better suited for finding new nebulae.
"I have used such lenses mounted on my 6.4 inches refractor with much success during the last few months."
After comparing his photographic work to visual discoveries of Barnard and Herschel, Wolf arrives at the new subject revealed on his latest plates:
"But the image of the nebula surrounding Zeta Orionis, a reproduction of which I have sent to the Association, is quite a marvelous object. The part of the nebula east of Zeta is G. C. 1227, drawn with much detail by Lord Rosse...The extremely large and interesting nebula S. W. of Zeta, also the nebulous ground around Zeta and the nebulous star north of Zeta, do not appear to have been seen before.
"The reproduction you received is an enlargement with an unimportant 'retouch' from a plate which I took on January 2nd, 1891, from 7h 0 til 12h 30 with a Kranz Euryscope of 5-1/4 inches aperture, using the 6.4 inches equatorial as a guiding telescope; and was relieved from my work by the Messrs. Rosenplaenter, Staus, and Zangemeister.
"Besides this long exposed plate I obtained also the same nebula...with a Voigtlaender Euryscope of 4 inches...(and) with a Millet portrait lens of 4 inches, with exposures of from 1 to 3 hours. (Plates from Messrs. Lumiere of Lyons.)
"I have still to add that I cover the back of the photo with a mixture of linseed oil and pine-soot to avoid the rings around the brighter stars, according to the method I published some years ago. Thus, I never obtain disturbing rings around the bright stars, even by the longest exposures." (105)
As mentioned in the account of Harvard's publication of the photographic discovery of the Horsehead nebula, the British journal's editor, E. Walter Maunder, adds a lengthy footnote clarifying and correcting Wolf's article.
"Miss Clerk has kindly drawn our attention to a paper by Mr. W. H. Pickering...in which he describes the discovery of a number of new nebulae by means of photography. On p. 116 there is the following note upon 'Nebula No. 21,' which is evidently that shown on Dr. Wolf's photograph."
The note subsequently quoted is the 1890 Harvard Annals' description of the nebula south of Zeta Orionis that contains the "semicircular indentation" we now call the Horsehead.
Maunder updates the older G. C. numbers employed by Wolf to the equivalent New General Catalogue numbers of Dreyer for the objects photographed near Zeta Orionis, and concludes:
"It appears then, that Dr. Wolf's photographs do not actually show any new objects. But they correspond most satisfactorily with the results obtained by a much larger instrument." (108)
The photograph by Max Wolf of the ''Nebula surrounding Zeta Orionis'' published on p. 297 of the 1891 British Astronomical Association Journal clearly shows the Horsehead, but suffers from the restricted gray scale of the primitive printing techniques of the era. The ''unimportant 'retouch'' that was probably required to clearly depict the sharp notch of dark nebulosity does give the photograph an artificial quality in contrast to the accuracy of the ''collotype'' prints of Barnard's Milky Way photos, but one can imagine that the original plate was a very good one. Star images are perfectly round and clean, showing excellent focusing and guiding; the absence of the distracting halation rings indicates an improvement over Pickering's achievements.
Some reprocessing to stretch contrast was done by the photo lab at Lick Observatory, but -- unfortunately -- that copy has been lost by Kalmbach Publishing. Thus, the picture was further degraded by our surviving photocopy, and required extensive digital image processing to improve the distinction; though IC-434 and the Horsehead region are recognizable, the result is unnatural compared to what one would expect from Wolf's original negative. The original 1891 publication showed the positive mode, as above; but perhaps it is even clearer and more distinct in the negative version we have prepared: click here.
Despite the limitations of the reproduction, this 1891 photograph portrays the Horsehead region much more dramatically than in the very small and low-fidelity image on p. 111 of the 1895 Harvard College Observatory Annals.
In addition to his work on the nebulae, Dr. Max Wolf was distinguished for many pioneering celestial applications of photography: multitudes of faint asteroids and numerous variable stars, plus comets and novae, yielded to Wolf's skilled method of search with the optical stereo-comparator, invented for another purpose but first employed for astronomy by the German professor in 1901.
Two final similarities between Wolf and Barnard must be mentioned. Each was associated with one observatory for the bulk of his career, the American at Yerkes for nearly a quarter of a century, and the German in Heidelberg for a patient and productive thirty-five years. In a concluding biographical note that could be equally and uncannily applied to Edward Barnard, Wolf's friend Hector Macpherson wrote of the great German astronomer's career:
"Wolf's activity did not appreciably diminish with the passage of the years. Despite failing health, he retained his [activities] right up to his death...The news of his passing occasioned deep sorrow all over the scientific world. One of the kindest, humblest, and most lovable of men, he had many friends as well as admirers.'' (107)
So we can add to his many achievements that when the 70- year-old Dr. Max Wolf died on October 3, 1932, not the least of his feats had been the 1891 publication of the first really satisfactory large-scale photograph of the Horsehead nebula.
THE WILLARD AND THE WORKAHOLIC
Lick Observatory Main Building Entrance on
near San Jose, California: photographed by author, 1989
The sight of the snowy crest of Mount Hamilton is an incongruity during shirt-sleeve weather in the Santa Clara valley. Winter seldom brings more than frosted tips to San Jose lawns, but January and February chills endow Lick Observatory at its 4200-foot elevation with the full complement of seasons denied to the valley below. The narrow, winding Mt. Hamilton road (with more than 350 turns and switch-backs) discourages all but the most sporting of winter visitors. Like their turn-of-the-century ancestors, the astronomers and staff at the observatory may occasionally be snowed in at the top, but the isolation is short-lived thanks to the bustle of road and utility service crews. Even when the drifts pile four feet high, the incessant babble of radio and TV signals -- almost too many of them, strong and clear at such an altitude! -- easily staves off the sense of withdrawal that made winter mountain life a century ago resemble a term of solitary confinement.
Our visits to the observatory are always in spring and summer, when the crisp, clear, and tranquil air acts as a tonic to lungs accustomed to Silicon Valley smog. Then the author and his wife (musician and teacher Regina Roper) meet with the UC/Lick history docent W. Shiloh Unruh to prepare for the annual ''Music of the Spheres'' fundraising classical music concert at the Observatory.
Since his childhood, Shiloh has been drawn to the hill as if by a magnet; he has lodged the century-old dry dust and plaster under his nails, has crawled behind walls and into abandoned nooks in the old main building, and has sifted through ashes for bits of old pottery and glassware. Seduced by the siren-call of history, Shiloh has scoured libraries for photographs of stern-faced men in celluloid collars and solemn women in florid hats; he has trekked the journey first taken by Lick astronomers back in 1889 to photograph a solar eclipse from the tiny California village of Cloverdale.
[Note: Mr. Unruh's official association with the Observatory came to a close around the year 2000; he later passed away, apparently at age 61, during a period while he was working as a volunteer for a project to restore the 12" Alvan Clark Telescope of Lick Observatory: see the article 12-Inch Alvan Clark Telescope Restoration (PDF) from the website that chronicles the restoration project, here.]
Shiloh conducts walking tours of the site of Lick mansion near downtown San Jose, and is saddened that this once quiet and fertile orchard property has had its ground and its sky polluted by 20th-century progress. He has even searched for the factory of old Charles Feil in Paris, the glassworks where the blank for the mighty 36-inch refractor was poured in 1885. (109)
James Lick, the homespun millionaire who endowed the Observatory, would appreciate one of Shiloh's hobbies: making fortepianos and harpsichords. The skilled carpenter and furniture-maker Lick began acquiring his fortune by providing pianos for the music loving citizens of Buenos Aires, Valparaiso, and Lima. (109)
In early September we gather again to present our concerts -- a few snippets of which you may audit on this webpage -- in the great telescope's dome, a dark cathedral-like confinement which opens up at night to admit a slit of starry sky into the enormous lens of the second-largest operating refractor in the whole world. For the short span of a decade, this marvel of 19th century's technology was the biggest such instrument in existence, and its power and precision could seek out tiny, obscure objects like the fifth moon of Jupiter, discovered by Edward Barnard in 1892, a scant two weeks after being permitted a regular observing schedule with the great telescope. (110) Yet such is the nature of long-focus refractors that this mighty Warner & Swasey machine needn't have existed in order for the Horsehead to be revealed. For it was not the huge Alvan Clark 36-inch objective, but an obsolete cast-off lens of only 6 inches' diameter that in 1894 first photographed the dark nebula at the Lick Observatory.
A noble machine, the Warner & Swasey-built Lick Observatory 36-inch Refractor, with objective lens by Alvan Clark & Sons. Photographed in 1989 by the author.
The unaccustomed crunch of winter snow under our feet reminds us that as amateurs, we are now present on the top of Mount Hamilton on a cold February afternoon by the permission and courtesy of the professionals who protect this outpost. We are led where visitors seldom go, into a private sanctum to inspect the preserved objects of this priestcraft with one of its senior practitioners.
Eugene Harland has been at Lick Observatory for three decades, coaxing images from all the instruments on the mountain. He has seen the photographic plate supplanted by the electrical components of the CCD, and has observed for the long span of years it has required to photograph a ''movie'' of the evolution of fascinating nebular Herbig-Haro objects, protostars emerging from the depths of dark globules of interstellar matter. (111) Gene has even discovered his own comet (an accidental by-product of another project) that turned out to have an estimated 800,000 year period. One wonders if earthlings will care to observe its return, and how they will differ from our current species!
Our small party of Horsehead researchers enters the Lick Observatory plate vault under Gene's watchful supervision. My companions are Richard Page, through whose own homemade 6-inch reflector I first observed in 1961, and the father-and-son astrophotography team of Ron and Ryan Wood.
The three of them are avid and skilled amateurs: Rich has built a massive and excellent 14-inch aperture German equatorial; Ron has figured his own superb 8-inch mirror, and prints his own and his son Ryan's astrophotos. An atypical 15 year old, Ryan patiently endures guiding hours-long exposures to secure crisp deep-sky shots of clusters, galaxies, and nebulae. Like Shiloh, I have caught and can't shake off the history virus, and am perfectly content to follow the same pathways that the professionals cleared a century ago.
An ancient safe that could have adorned a Northern California 'forty-niner' assay office, and ornate wooden cabinetry that would have impressed master carpenter James Lick, fill the first of two elegant rooms that contain the original photographic plates that have slowly accumulated for a hundred years. These glass relics are instructive to the late-20th century technological chauvinist, for they demonstrate that the art and science of astronomy and photography were mature and profitable during the first decade of the Observatory's operation: the information contained on these old plates can long benefit researchers who study novae, proper motions, and stellar evolution by accurately verifying the state of the heavens many long years ago.
In the inner rooms, arranged as a lengthy corridor broken by two huge doors that help maintain a constant temperature and freedom from moisture, are the oldest of the plates and observing records. Ceilings are at least ten feet high, and one must climb a ladder to reach all of the shelves, which are enclosed in fine-crafted glass cabinets to keep out the last speck of mountaintop dust. The right-hand wing contains the observering books of the early generations of astronomers, recording their impressions as they worked at the telescopes, spectroscopes, and cameras; or their later reductions of data, laboriously calculated without the benefit of modern electronic computers.
The hundreds of fancy bound volumes of lined paper, neatly labelled on their spines with the initials of S. W. Burnham, E. E. Barnard, E. S. Holden, and all the rest, remind one of the library of a Victorian law office, but when we open them we are confronted not with torts and arguments, but a bewildering array of handwritten scribbles, mostly in pencil, of fragmentary comments, Greek letters, tables of figures, and planetary or lunar drawings.
Burnham's penmanship -- especially his elegant signature -- is regular, readable, and beautiful, while that of Lick's first Director, Dr. Holden, is bold and forceful. But we resist the temptation to while away time and soak in impressions, being here to examine the notations of Edward Barnard and specifically to see any comments on his Milky Way photography can shed light on his early knowledge of the Horsehead nebula. Auto-didact Barnard spent but two months' attendance in school as a child, (112) and his scrawl is sometimes clumsy and crude: it will be necessary for two or three of us to examine the markings and discuss what they must mean.
Gene knows that with the enormity of the material present, a blanket search will be time-consuming and fruitless, so he insists that we start with the exact dates that Barnard photographed the constellation of Orion. I have brought copies of Barnard's famous Milky Way photos in the 1913 Lick Observatory publication, so we should know the precise date that the first Horsehead picture was obtained on the mountain, but the heavy books are still in my car, a quarter-mile away down a long, icy, winding road up to the main building. Ron Wood starts the slow, slippery journey on foot since Gene is loathe to permit me to start rifling through the notebooks. While waiting for Ron, I examine the plate room with Gene Harland.
In a duplicate set of glass cabinets are the oldest of the negatives taken with the Lick refractors. I glance down near the floor at a collection of enormous survey plates in a cubby-hole labelled "Vulcan, 1905." Inside ancient manila envelopes, much thicker than today's paper, are fragile photographs taken from a search for the chimaerical intra- Mercurial planet that was supposedly seen by an amateur, the French physician Lescarbault, in 1859. For over 50 years afterwards it was hunted in vain. At each solar eclipse, when the best hopes existed for capture, a glimpse or photograph of the elusive disk without the intense obscuring glow of scattered sunlight, Vulcan was sought, fueled by claims of purported sightings and the press-agentry of such newspaper popularizers as Camille Flammarion, who also eagerly promoted the existence of the Martian canals.
In the first years of the 20th century concerted efforts were made by Mt. Hamilton astronomers to verify Vulcan's existence, but Lick Observatory's second director, W. W. Campbell, concluded after a 1908 eclipse expedition that further search was pointless, and soon the supposed body was generally declared nonexistent. (113)
Jestingly I asked Gene to point out Vulcan on the old plates, and for a moment I believe he thought I was serious, for he began patiently to explain that it didn't exist (in 30 years on the mountain, one has had to dispel politely a lot of the public's quaint notions of astronomy.)
While we waited for Ron to return with the notebook, Gene showed us what may have been the Observatory's second photograph of the Horsehead contained in a magnificent 1911 plate taken by the Willard lens and the Crocker telescope. It wasn't immediately apparent who managed the photography; perhaps it was Heber Curtis. It was certainly a beautifully guided, perfectly focused plate: worthy of that skilled astronomer, who was acknowledged "master" of the mountain's recalcitrant Crossley reflector.
It is impossible to exaggerate the delicacy of the images on an original frail astrophotographic glass negative. Unlike low fidelity and contrasty half-tone magazine reproductions or grainy drugstore sky prints that many amateurs are used to examining, a genuine glass stellar negative posesses an airy pointillism of faint markings and microscopic dots. On this exposure, the tracery of 1C-434 was such a fine and shadowy powdering that one could almost imagine the slow accumulation of each fugitive photon on the old, slow emulsion. Yet the Horsehead region was so starkly transparent against the weak dusting of nebulosity that this sharp ''dead spot'' appeared as though it had been scraped clean from the dim remnants of skyglow. The camera's wide field had captured almost the entire constellation of Orion, so that one had to hold the plate up to a strong light to see in the region south of Zeta Orionis the tiny 2-millimeter Horsehead.
After we obtained the date of the original Barnard plate of the constellation, Ron, Ryan, and Rich scoured the appropriate notebooks for any interesting comments. Sure enough, on the night of October 3, 1894, Edward Barnard scrawled his references to the photography of Orion, but with no illuminations in later pages about any discoveries of objects upon the plates. We can be certain, however, that the diligent Barnard spent long hours with a magnifier plotting and measuring each of his pictures, and was well aware of the ''curious nebular ribbon'' containing the Horsehead by the time of the publication of his 1903 paper on "Diffused Nebulosities in the Heavens." (114) In Barnard's 1894 Willard photograph, as reproduced in the Lick Publication of his Milky Way and comet photographs with the Willard lens, the Horsehead is fainter than the image on the Pickering discovery plate, and no wonder: Gene showed us a reference card on the Willard lens, recording that Barnard used a diaphragm between the front and back elements of the Petzval lens doublet pairs, cutting the aperture down to less than 4 inches. (115) This tiny area of glass, employed in the shadow of the great Clark 36-inch refractor, provided Edward Emerson Barnard with the raw material for the pondering of the next three decades of his life.
Edward Emerson Barnard
Edward Barnard in the 1890s, courtesy of the Mary Lea Shane Archives of the Lick Observatory
The full-length biography E. E. Barnard by William Sheehan, published in 1995, is a most commendable account of a tale of triumph over adversity: The Immortal Fire Within - The Life and Work of Edward Emerson Barnard. It had not been published at the time of the research and writing of this original paper, which drew on direct sources from Lick Observatory archives and historical publications.
Reuben Barnard died before his son Edward Emerson was born on December 18, 1857, forcing the youngster's mother to eke out a hard existence supporting herself and two sons by taking on various jobs, including has been written, classic American modeling wax flowers. The trauma of the Civil War deeply affected the boy, who could never forget the clash of arms at the Battle of Nashville. Edward was racked by malnutrition and cholera, and for the rest of his life carried a scar on his chin from a sore that his delicate constitution couldn't heal. (116)
Seventeen long years working for a Nashville photographer, beginning as a mere boy to help operate a huge enlarging camera that had to track the sun, prepared E. E. B. for a career that required calm, centered patience.
"About this time," writes Barnard's friend S. W. Burnham, ''a traveling show-man with a small glass for street exhibition turned up in Nashville, and young Barnard was a steady patron whenever nickels were sufficiently plenty to warrant such a dissipation.'' (117) Interestingly enough, such a peripatetic astronomer had visited James Lick at his mansion in 1860, staying for a few days to demonstrate views of the heavens to the fascinated old man, who was not usually wont to display much hospitality. (118) A rather similar experience had occurred to the master optician John A. Brashear, when as a 9-year-old lad 1849 he had paid a small fee to one ''Squire Wampler'' of McKeesport, Pennsylvania, for a view of Saturn and the Moon. (119) The lives of these three men were to be subtly intertwined in the eventual production of the famous Milky Way plates that had brought our present little group of amateur researchers to Mount Hamilton.
Edward's subsequent self-study of astronomy and efforts to improve his back-woods demeanor are well known. Burnham recalled that ''Handicapped by the sorest distress and poverty from the first he has fought the battle of life alone and is in the supremest sense of the word a self-made man." (120)
Conscious of his humble status but compelled by interests and ambition, Barnard sought a brief audience with the esteemed theoretical astronomer Simon Newcomb, who gruffly discouraged the unschooled youth from expecting any success as a professional scientist, dropping but a few scant words of encouragement for the boy to be a seeker of comets, an activity that required little mathematical knowledge.
Barnard departed in tears, but would soon make a name for himself as the prolific discoverer of ten comets by the time he would receive an appointment to join the staff of Lick Observatory in 1887. (121)
Like great creative compulsives from Beethoven to Bonaparte, Barnard obsessively drove himself towards achievement in prodigious outpourings of energy, but he had the inner-directed stability, lacking in dilettantes and dabblers, to focus his efforts and produce significant results. Soon the grip of comet-seeking fever overcame him, and he even dreamed one night of a sky full of multitudes of the fuzzy, streaming bodies; upon awaking, Barnard discovered that the bright comet of 1802 had broken into 10 or 15 fragments, which he duly swept up in his telescope and reported by wire. But his telegram failed to reach its destination, and thus he lost the credit for this particular find. (122) Nevertheless, the money earned from his other awards for cometary pursuits paid not only for his abode, called ''Comet House", but also for Barnard's tenderly solicitous care for his frail invalid mother, whose mind had slowly dimmed from the struggles she had endured. (123) Barnard was greatly aided by his faithful wife, born Rhoda Calvert in England, whose brother had been Edward's colleague at the photography studio. Mary Calvert, Barnard's niece, was later to assist the astronomer as his secretary, compiling and cataloging over 900 articles and papers; his published works eventually numbered nearly a thousand. (124)
When Barnard arrived at Lick Observatory in the early summer of 1888, he had accomplished much already, not the least of which was his diligence in earning against all odds a Bachelor's Degree in Mathematics from Vanderbilt University while working as an undergraduate astronomy instructor. But one imagines that in comparison to the scholarly James Keeler and John Schaeberle, Barnard's colleagues at the new observatory, the young self-taught zealot may have been regarded by Lick Director, Professor Edward S. Holden, with some faint condescension. Barnard may have been slightly tainted because most of his discoveries had been made, after all, while he was still 'merely an amateur.'
Edward S. Holden in the 1890s, courtesy of Dr. Donald Osterbrock and the Mary Lea Shane Archives of the Lick Observatory
Holden, whose rather bug-eyed intensity and arrogance glowers from every portrait, was an astronomical blueblood and an accomplished military man- turned- academic. It is clear that Barnard had somewhat cringingly courted the new Director, for he wrote on August both, 20th, 1887, "...I had made up my mind this summer to cease Comet Seeking and to get into a higher class of work."
(At the time, before astrophysics was much advanced, comets were of little interest to professionals. They seemed merely to be transient forms of those 'damned annoying nebulae' that got in the way of astrometers, working primarily to refine better star positions and catalogues for the purpose of improved timekeeping and technical references. Comets may have given Barnard financial comfort, and public status, but he well realized that he'd have to present himself as a seeker after "more important things" to impress a learned Doctor and Observatory Director!)
He continued, as if addressing royalty (rather in the manner of Bach humbly offering his 'little talents' in dedicating some concerti to the august Margrave of Brandenburg), "I hope you will aid me in this determination. My associations here (at Vanderbilt) have been the pleasantest, and I leave only because of the superior advantages that the Lick Observatory will afford me. Another strong inducement is (for I have always had the highest admiration for you personally) that I shall be immediately under your charge, and shall receive the benefits of your training.'' (125)
Knowing of the conflict he was to suffer, one is saddened to scan the original letter of Barnard as preserved in the Lick Observatory's Mary Lea Shane archives: chafing with frustrations under a Director he came to feel, in a pathological and exaggerated estimation, was little better than a fraud and scoundrel, Barnard nonetheless discovered Jupiter's fifth moon; created the Milky Way photographs (revealing of many of the sky's dark nebulae); discovered the first comet found by photography; made innumerable observations of newly-seen double stars, asteroids, and nebulae (many now known to be galaxies); carefully measured positions during occulations and eclipses; and left superb drawings of planets and the Moon. (126)
Despite the opportunities provided for such accomplishments, Barnard would soon lose his awe and regard for the authoritarian Holden, accusing him of "taking special delight in goading me", (127) diverting precious energy from observing into dueling with Barnard's implacable enemy "The Devil", as the Director came to be characterized by mutinous members of his mountaintop staff, perpetually spurred on by the affronted Tennesse astronomer. (128) Barnard's wild, manic swings of attitude, from nearly fawning hero-worship to obsessive hatred, might suggest that, at least during his Mt. Hamilton days, Barnard had a touch of bipolar disorder.
Holden's imperious attitude, and the consequent reactions of his skilled and sensitive underlings, can be judged from as little as two brief documents from the Shane archives. Tempers soon flared at the Observatory, with the Director and his disgruntled astronomers communicating officially by passing memos back and forth, designed to present for the scrutiny of the University of California regents their respective positions in each altercation, disagreements sometimes petty but often deep and divisive.
The first of these two examples reads:
''September 18, 1890
Professor Edward S. Holden
We insist at all times that whatever difference of opinion there may be between our views upon scientific subjects -- your conduct, both oral and written communications, shall be gentlemanly.
Among other things in your communications of yesterday the use of the word sneer is unworthy of your official position.
S. W. Burnham
Attached is the response of the Director, penned neatly in the bold broad hand that reflected his strong military bearing:
''Sept. 16, 1890
Not answered. Filed with the suggestion that the writers have evidently forgotten the expressions employed by them in speaking to me of my letter to Mr. Crocker relating to the missing vouchers to their eclipse accounts.
E. S. H.'' (129)
A graphologist would take note of Holden's dramatic detached flourish on the final s of the word ''vouchers", perhaps betraying his smug satisfaction at having found an alleged example with which to discredit his critics. Obviously all parties to any of the disputes were going to insist that each argument would have two clearly-drawn sides.
With due credit to Director Holden, it must have been wearying to arrive early at his desk in the morning, fatigued from a night spent observing until 12 o'clock in the frigid dome of the great refractor, and after stoking the reluctant fire in the smoky hearth -- great winds blowing through the chilly building, blowing about any hapless missive -- to sit down at last at his desk, only to confront on the very top of a stack of documents an angry submission from a fuming Barnard, such as the following memo of September 2, 1895:
''To Professor Holden.
My sleep is constantly being broken in the mornings by the observatory wagon going back and forth by our house to the Crossley telescope. To one working all night this loss of sleep is distressing. This occurred again this morning, after I had got but little sleep, by the heavy team coming over to get a lot of packing cases that have lain there for a month or so. I respectfully request that this unnecessary nuisance be stopped and when possible such work be done the afternoon. Respectfully,
E. E. Barnard'' (130)
A subtle inference must be noted: Holden had arbitrarily denied Barnard official access to the world's largest telescope, though the Director reserved it for himself on two nights of each week. A clumsy and desultory observer, Holden produced photographs that were too often blurry and useless. (131) Tiring by midnight or so, the Director would frequently close the dome and trudge off to his dwelling, leaving the great, indispensible scientific instrument quite idle.
Barnard the brilliant observer and voracious comet-discoverer was not even permitted to use it after Holden retired for the evening, as presumably this would have been too embarrassing for the Director.
Note that Barnard reminds Holden pointedly, ''To one working all night", [Waldee's emphasis] "this loss of sleep is distressing." Holden's justification, printed on another occasion in an article written for the Journal of the Astronomical Society of the Pacific that the professor himself edited, explained that, "Before the least scientific work can be done, life (on Mount Hamilton) must somehow be organized...The energy that is left over is available for astronomical work.'' (132)
The Director's high-handed behavior eventually caught up with him, and became something of a scandal, noted in the newspapers: the regents could no longer ignore it nor discount the disagreements at the Observatory as being merely the prattlings of neurasthenics suffering from isolated mountain-fever. As befitting his sense of dignity, Holden's departure from Lick Observatory was not accompanied by Shakespearean dramaturgy. With public opinion heavily on the side of the astronomers, he quietly packed and left prior to his official resignation. One job after another eluded him, so Holden supported himself by writing torrents of articles, not all on astronomical subjects. Dr. Donald Osterbrock notes in his monograph ''The Rise and Fall of Edward S. Holden'', that the former esteemed Lick Observatory director and scientist was not above churning out a light essay on etiquette (''What is a gentleman? A Lady?") under the pseudonym Adam Singleton for the old Cosmopolitan Magazine. (133)
A lasting accomplishment at the end of his career was a return to West Point for the position of librarian. There the bibliophile Holden could work in an atmosphere pervaded by ''an infusion of some military order'' (134) that he had not managed to sustain among the rugged individualists atop Mount Hamilton.
How remarkable it is that today, a century after the struggle between the established and respected Edward S. Holden and the upstart but sincerely dedicated Edward Emerson Barnard (called neurotic by Osterbrock based on his extensive study of the myriad of self-pitying letters in the Shane archives), (135) the tables are firmly and irrevocably turned. A few hoary remnants of Holden's personal works can be unearthed, such as a pitifully slim and sketchy volume on the life of William Herschel, preserved in the University of California Science Library in Santa Cruz, or in his literate but technically- thin dissertation on historical visual observations of the Orion nebula (characterized by Osterbrock as being written more like Goethe than a conventional scientific paper. At least the present author rather enjoyed it, and all the historical woodcuts and engravings within, having spent days finding, at last, a moldering copy, nearly buried in the depths of the uncirculated obsolete Observatory documents at the University of California in Santa Cruz in 1989; it is now solidly packed away in unaccessible permanent storage!)
If Holden was, a quarter century later, now nearly forgotten, Barnard's accomplishments caused him to be venerated -- almost idolized -- by his former colleagues, judging from the threnodies published just after the great observer's death on February 6, 1923. (136) Holden's true legacy must be measured indirectly, from the establishment of a progressive policy of photography and astrophysical research at Lick Observatory, to the acquisition of the Crossley 36-inch "fast" reflector, and the creation of the famous Lick astronomical library.
Anyone who has held a sometimes thankless executive position cannot despise Holden for failing to secure a perfect balance between establishing the needed mountaintop discipline, and nurturing the occasionally conflicting needs of the University administration, highly-strung astronomers, and the public benefactors of Lick Observatory. "We are all more or less like the horses of these mountains! We get 'loco' as they say," wrote Holden to a U. C. regent in 1892. (137) But despite a sad demise, Edward Singleton Holden was far from being merely the Captain Queeg of the ship afloat the starry realms of Mount Hamilton!
THE QUIET, STEADY WORK OF A PATIENT GENIUS
Now the stage has been set for the work of Edward Emerson Barnard in the tiny dome near the old water tank on one of the hilltops at Lick Observatory. A superb old black-and-white photograph of the era shows the master's gentle touch applied to the Crocker telescope controls, his arms outstretched tirelessly to operate the right ascension and declination guiding adjustments during long exposures of the slow dry plates affixed to the rear of the Willard camera; one might almost imagine hearing the echo of the slow, steady ticking of the clock drive inside the dingy tin dome. Barnard will remain standing in this uncomfortable position for up to 5 or 6 hours at a stretch, his eye glued to the ocular of the guiding telescope, as he precisely regulates the tracking clock which follows the relentless sidereal motion of the heavens. His eye never leaves the defocused image of a bright star, the soft flickering blob of light behind the fine iron crosswires of the guiding eyepiece. (138)
From time to time he will have to wind the clockworks without spoiling the plate, and to push the dome around to keep the clear sky always in front of the optics. No assistant helps him; no heater may be employed lest its radiant waves spoil the sharpness of the images; no electrical appliances provide the torque to spell the labor of his muscles; and no radio plays softly to entertain him with soothing music during the long hours. If the camera slews across a great arc of sky, he may have to fiddle carefully with the dangling counterweights of surplus iron to compensate for changing atmospheric refraction, maintaining pinpoint-crisp stellar images on the negatives.
Edward Barnard, obscured by controls of the Crocker Telescope with the Willard Lens, Mt. Hamilton, courtesy of the Mary Lea Shane Archives of Lick Observatory
Wind rolls up the sides of the hill, whistles and howls through the rattling dome and building, its chill creeping into the observer's bones. Distant coyotes cry out in the night, bringing no frisson of fear for the sky is far from being frighteningly black: photons from the innumerable stars of the Milky Way stream through the slit, bathing the inside of the sanctuary with dim grey starlight, an effete eery glow like the dregs of energy strained from the sun until almost nothing is left to shine. This may be work for a poet; and indeed for one who is not faint of heart.
An astronomer, like no ordinary woman or man, measures time in decades, centuries, millennia, eons. Barnard will be patient: the perfect images on his precious plates, recording plangent waves of luminosity, the dense knots, chains, and swirling maelstra of clusters and asterisms, rifts and sudden black depths, fleecy stellar cumuli, and the mysterious elliptical nebular smudges, will become known to his colleagues and the public only when just the right conditions prevail. It will be necessary to secure official approval; to acquire considerable funds to cover plates, chemicals, and every other conceivable little expense; and to experiment almost endlessly with printing techniques to satisfy the perfectionist, always paying for every "retake".
In all, more than two decades must elapse after the Milky Way impressed its light on the earliest of the plates, for the now-famous but unseen pictures to be published. Imagine the different pace of life then, versus today: would such elderly research still be considered fresh and exciting some twenty years after its completion? Yet Barnard's photographs revealed then -- even to professionals -- a richly detailed architecture of the sky not perceived visually through the old-fashioned long refractors.
By the time that Volume 11 of the Publications of the Lick Observatory came to be printed in 1913, E. E. Barnard had mellowed. Now a distinguished professor of astronomy at Yerkes Observatory, required to teach no students but merely to observe, photograph, and ponder (139), and treated with compassionate warmth by its founder George Ellery Hale, Director Edwin Frost, and all his contemporaries, Barnard was free from some of the insecurities that had made his earlier days so painful; yet though he had won the Lalande Gold Medal of the French Academy of Sciences for discovering Jupiter V (140), he was only too aware of his own and fellow astronomers' limitations of knowledge when confronted with the mysteries of the Milky Way.
Barnard's intellectual honesty compelled him to confess in the pages of the Milky Way publication that he had erred in improperly fixing the images on the earliest plates, in dramatic contrast to the supremely self-content Holden. (141) Perhaps his inner demon kept Barnard a sweet and decent man, in the words of Yerkes colleague Philip Fox:
''...marked by a great simplicity of character, great modesty, perfect unselfishness and self-abnegation; a most kindly and genial spirit. Most tender-hearted, making any distress of his friends his own distress, of such character as to make him genuinely loved by all who knew him; his home was one of cordial hospitality.'' (142)
Barnard could be a hearty soul, often singing the darkroom in a not-too-gifted voice. (143) His sense of humor can sometimes be evident even in the pages of a scientific publication, judging from this amusing account of one obscure aspect of making the Milky Way photographs:
''To judge from the almost entire absence of electrical storms on Mount Hamilton, one would get the impression that very little electricity was present in any form. While guiding, in making these photographs with the Willard lens, however, the writer frequently met with a singular experience which, while it may not be a new one, was at least an unknown feature to me at the time. Perhaps I may be permitted to describe it in connection with the present work.
"On chilly or cold nights I wore an Esquimaux [sic] coat made of reindeer skin, and heavy rubber overshoes. Frequently, on bringing the eye to the telescope on such nights a spark would discharge with a slight shock between the eye and the eyepiece. This was extremely annoying, and finally became so disagreeable that it was found convenient frequently to touch the metal instrument, which would produce a discharge from the finger instead of from the eye. The probable explanation of this phenomenon is that it was due to the fur coat and the insulation of the rubber overshoes, the body becoming electrically charged like a Leyden jar. The approach of the eye to the eyepiece would discharge this electricity into the telescope from the eye. This phenomenon, under similar circumstances, sometimes occurred in observing with the 36-inch refractor. Neither telescope, at that time, had any electrical appliances.
"On one occasion, when going to bed in the early morning, the conditions were such that rubbing the hands over the sheets produced a perfect shower of sparks, apparently threatening to set the sheets on fire." (144)
No doubt this account speaks much of Rhoda Barnard's patience, and should be of some solace to many an astronomy 'widow'! (The present author must confess that during a 1991 astronomy club lecture in Oakland, he was reading this commentary of Barnard, as part of his talk about the Horsehead. Suddenly an inspiration spontaneously struck him: to use a probably likely simulation of Barnard's soft Tennessean accent. At the conclusion of the anecdote, the audience was absolutely stunned and delighted--much as were, we'd suspect, the pleased audiences of Barnard's own very popular public lectures!)
In the early Lick period, full of his mission but all too aware of his humble beginnings, the ambitious astronomer fussed over a statement published by Holden that ''Mr. Barnard had made some experiments (in photographing the Milky Way)...in 1889, with the promise of most satisfactory results.'' At the time, Barnard had replied with fervent protestations that his work was emphatically not experimental, and felt it was thus being diminished by an unappreciative and spiteful Holden (one, now, might surely agree with him, and 'feel his pain'.) (145)
Yet by 1913, the matured Barnard could himself write in the Lick Publication Volume 11 that, ''The results of some experiments which I made (with the 6-inch Willard lens)...in photographing the Milky Way were very beautiful and intensely interesting. When the importance of the lens for such astronomical work became apparent, Professor Holden placed it in the hands of Brashear, who refigured it and greatly improved the definition of the star images.'' (148)
Barnard earlier in the same work pays his homage to the previously-reviled ''Devil," writing: "I am indebted to professor E. S. Holden, former Director of the Lick Observatory, for placing the Crocker Telescope at my disposal for the work of securing these photographs.'' (147) The conventions of good manners and the protocols of professionalism may conceal Barnard's true feelings. but as he was by all accounts a benevolent man, it might be best to suppose that he was at last charitable to his old adversary.
Central Portion of Orion Belt Region: Photographed by E. E. Barnard, 1894 - by permission of Mary Lea Shane Archives, Lick Observatory. Scanned from Lick Publication Vol. 11 by Dr. Harold G. Corwin, Jr., 2012
Horsehead Nebula, and IC-434, positive and negative: Barnard, 1894 - by permission of Mary Lea Shane Archives, Lick Observatory. Scanned from Lick Publication Vol. 11 by Dr. Harold G. Corwin, Jr., 2012; cropped and processed by author, 2012.
The scene crossfades back again to the late 20th century...
Gene Harland led Rich, Ron, Ryan, and me over the short but nonetheless perilous and icy path back to the high-vaulted main building of Lick Observatory and, past the old post office boxes of the mountain dwellers, down a hallway in a remodeled section that was reminiscent of modern school corridors, to another off-limits repository. Through a room neatly stacked floor-to-ceiling with cardboard fileboxes of Observatory paperwork, we stepped across another time warp threshold to a treasury packed with the silvery coinage of collected starlight. Row upon row of metal shelves on one side contained multitudes of copies of Lick Observatory publications, here a paper on spectral analysis of one stellar body or another by means of the Mills Spectrograph, there a volume of the nebular photographs made at the turn of the 20th century with the 36-inch Crossley reflector. On the other side of this long vault of astronomical history was another antique cabinet bearing a proud woodworker's art. Behind glass windows reposed slightly tarnished and well-used micrometers. ancient electric lamps, and enormous eyepieces with massive fixtures and attachments unfamiliar to modern amateur astronomers, the precisely-crafted instruments of the old astronomy of a slower if not always more cordial age.
Gene Harland stooped laboriously to retrieve a heavy, unwieldy object. He and Ron stepped back and held up the Willard lens for the rest of us to acknowledge.
Willard Lens in 1989: left to right, Rich Page, Steve Waldee, Ron and Ryan Wood.
E. E. B. himself recounted the history of this instrument in the publication of his Milky Way photographs. Willard was not the maker, but the dealer for large portrait wet-plate cameras that soon replaced the old Daguerrotype process. In 1849, one Charles F. Usner in New York City actually constructed the lens, a Petzval type objective consisting (in Barnard's precise calculations) of front doublet elements of exactly 5.85 inches aperture with solar focus of 42.59 inches, and rear elements of 6.73 inches diameter, focal length of 70.2 inches. Together, their cone of focused light fell exactly 778.9 millimeters distant onto the photographic plate. The scale of image obtained was 1.81 degrees per inch. If one were self-taught Edward Barnard, Bachelor of Science, writing in the Publications of the Lick Observatory, it would not do to round off to tenths of an inch or centimeters! (148) Today a typical 35-millimeter film camera sports a lens of but 2 inches of aperture; in Matthew Brady's time the slow wet collodion plates required exposures of several minutes' duration of subjects bathed in bright sunlight and magnified by huge lenses. Young Ed Barnard was all too familiar with the practices of the old photographers, with their stultifying poses and dangerous chemicals. But when the ''sensitive'' dry plates were introduced a few decades later, the gargantuan lenses -- such as Usner's -- became obsolete for commercial purposes, and were now available as relatively cheap surplus.
Barnard recalled his slightly stilted and proper style that:
"The advent of the Willard lens into astronomical work was due to the eclipse of the Sun, which was visible in northern California on January 1, 1889. Through the influence of Professor Holden, a large number of amateur photographers, especially those in San Francisco and neighboring cities, became greatly interested in this eclipse. Under the general supervision of Mr. Charles Burckhalter of the Chabot Observatory, Oakland, California, these amateur photographers, many of whom were very skillful, were assigned positions on the line of totality to secure, with crude appliances, the best results obtainable in the representation of the corona...Mr. (William) Ireland was especially fortunate in being able to secure the use of a large portrait lens of some 6 inches aperture and 31 inches focus, which he borrowed for the occasion from Wm. Shew, a photographer on Montgomery Street, San Francisco, who had used the lens, which had originally cost several hundred dollars, for making fashionable portraits (especially in the later sixties)...
"...impressed by the excellent results from the lens, Director Holden purchased it from Mr. Shew for the Lick Observatory with funds provided for the purpose by Hon. C. F. Crocker." (149)
Ah, "six degrees of separation"... the present writer, a Barnard fancier and amateur astronomy historian and observer himself, cannot help but note that he spent many years working for a classical music station partly owned by a descendant of the same Crocker. It had a very powerful signal, from a mountain top in Marin County: if FM radio had existed in the 1890s, no doubt its beautiful music might have reduced the mental strain of Barnard's toils!
Decrepit and unusable original Crocker dome, which would have been seen between the two domes in the author's 1989 photo below, was removed in 1950. Dome at left is for 36" refractor; smaller dome at right is for 22" Tauchmann. Click here for aerial layout diagram of various domes.
One supposes that a great musician might behold Nicolo Paganini's Guarneri ''del Gesu'' fiddle with the awe that we amateur astronomers hold for the Willard lens, to anyone else perhaps only an elderly relic, looking more like part of an old furnace than an historic stellar camera. Somebody had surely spent much energy and elbow-grease in shining up its brass exterior for the fancy frontispiece picture in the 1913 Lick Observatory Milky Way publication, but by 1990 it was faded and neglected in its glass cabinet.
Despite the Willard's outward homeliness, its mere existence serves to teach a moral lesson that great accomplishments are borne of effort and sacrifice, and all else is vanity. We posed with the Willard, as Gene's sure hand snapped the shutter on the centenary of the Horsehead's discovery. I'm sure that all patient astrophotographers, hypnotized by the stillness and magic of the night, would appreciate the homage to Barnard and his labors.
You may also enjoy reading the Lick Observatory Historical Collections Project, which has a page on Barnard and his work and instruments.
THE SUCCESS OF A FAILED EXPERIMENT
Was Herschel wrong?
At the end of the 19th century there were at least two important questions about conclusions drawn by William Herschel in his ''Construction of the Heavens": did diffused nebulosity exist in the profusion claimed, and did its sudden diminution in those remarkable dark spots truly constitute ''holes'' in the heavens?
These queries arose as a new science evolved: astrophysics.
The old astronomy of long refractors and painstaking visual micrometry had preferred to deal with the precise issues of what could be indisputably observed and measured, most positional astrometry employing data sets based on the brightest and most clearly discerned stars. Telescopes were as likely as not erected for convenience in great cities whose night skies suffered from the smoke of burning wood and coal, though these bright specks of light could penetrate much of the fog. But the great leap in sensitivity provided by photography had begun to teach the lesson of the amateur William Herschel, a cry soon to be taken up by George Ellery Hale: gather more light! With that light came the energy for operating the spectroscope, to reveal the chemistry of stars.
Even if focused by small lenses, the radiant bath of sunlight was sufficiently powerful to provide a bright rainbow of colors in the viewing oculars of the earliest telescopic spectroscopes. Joseph Fraunhofer, creator of the archetypal Dorpat refractor, was first to couple a prism to a telescope shortly after the turn of the 19th century, placing the glass in the focus of a 4.5-inch doublet. Eight prominent dark lines in the spectrum from darkest red to deepest violet were labelled by Fraunhofer with the letters A through H; hundreds of finer ones were also visible, and by increasing the dispersion of these closely-spaced markings with a cylindrical lens, he could obtain them also in the light of bright stars, but in different patterns than those provided by sunlight. Introducing a finely-lined grating instead of a prism produced a less-contracted dispersion of the colors, permitting measurements of wavelength on a uniform scale. (150)
The British scientist William Hyde Wollaston had discovered as early as 1802 that this series of dark lines always kept relative order and positions, though he failed to understand their true nature. When Gustav Kirchhoff and Robert Bunsen concluded from their 1859 experiments on the ''D'' lines of sodium that the dark lines in the spectrum of sunlight represented an absorption of light by the incandescent elements of the solar atmosphere, whose constituents could be determined by mapping the spectral lines -- as indeed could the components of any star sufficiently bright to produced a spectrum -- a revolution in physics had quietly occurred.
"A new era in astronomy had begun", to quote Henry King, "to be compared only with that which followed the invention of the telescope." (151) Now was possible to study the very nature of the mysterious forces emanating from the heavens; not merely to observe, but to learn and theorize, using the crucible of the stars as laboratories for experiments of the mind.
A quarter of a century before the first photograph of the Horsehead nebula would be accomplished, Britain's William Huggins was attempting to employ the wet collodion photographic process to capture bright stellar spectra at his private observatory in London, in a small private facility constructed when the amateur Huggins gave up manufacturing draperies in 1854 to turn full-time to science. (152)
His fine Alvan Clark 8-inch objective, mounted equatiorially by Thomas Cooke, had been satisfactory for visual observations of the planets, but its smallish aperture could not focus enough light to register photographically the dark lines visible in the spectra of even the bright stars Sirius and Capella. So Huggins was restricted to visual observations, requiring enormous patience to endure the fluctuating, turbulent images. ln order to identify the wavelengths of the lines observed, Huggins compared them to known spectra produced by arcs of electrical current conducted across selected pairs of metals.
When he finally turned his Clark refractor onto a planetary nebula in the constellation of Draco during the evening of August 29, 1864, Huggins was stunned:
"I looked into the spectroscope. No spectrum such as I had expected! A single bright line only! I first suspected some displacement of the prism, and that I was looking at a reflection of the illuminated slit from one of its faces...then the true interpretation flashed upon me. The riddle of the nebulae was solved. The answer, which had come to us in the light itself, read: Not an aggregation of stars: but a luminous gas." (153)
After achieving immortality for his first recording of the spectrum of a planetary nebula (NGC 6543), Huggins was the earliest investigator to utilize the phenomenon of the Doppler shift to measure the radial velocity of the star Sirius some four years later. (154) The development of fast photographic emulsions, recording the light gathered by large reflectors, would in a few decades enable astrophysicists to wield these powerful spectroscopic measuring techniques vastly to extend the size of the known universe to proportions that would have astounded Copernicus.
Now the scientific value of increasingly detailed and accurate stellar position measurements would be secondary to the exciting frontier of spectroscopy. A new breed of synthesists was to appear: men -- and now at last women -- who could analyze the data gathered by means of photometric spectroscopy, photography, and statistical studies of stellar populations, radial velocities and proper motions; once their imaginations had reached ''escape velocity" from Newtonian gravitational theory (thanks to Albert Einstein) the science of modern cosmology would be born, taking a huge leap beyond the prior domains of theologians and philosophers.
The era of the refractor telescope was ending. The silver metal-on-glass reflector (even if it be less accurate in image quality, less stable in efficiency, and more challenging to construct and mount) was inherently achromatic, directing a wider, purer bandwidth of lightwaves into the spectrogram's slit or onto the photographic emulsion, recording more of the hot, energetic photons emitted by the powerful young stars that were the engines of many of the nebular regions first spied by Herschel.
A Modern Bandpass Filter for Visual Examination of Nebular Lines in the Visual Spectrum, Eliminating Much Pollution Generated by Streetlights and Airglow.
Max Wolf was an early and avid spectroscopist. His researches on the nebular streak IC-434, featuring the phenomenon of the Horsehead, and the nearby ''fuzzy star'' NGC-2023, published the Astronomische Nachrichten in 1909, indicated that he had utilized his Heidelberg Observatory's reflecting telescope to obtain a specific light wavelength radiated by the gaseous nebulae, now shown by the spectroscope to be associated with ionized hydrogen: the prominent Balmer line at 486.1 nanometers, the hydrogen-beta line. (155) The film emulsion of the time was most sensitive to "actinic" (bluish) wavelengths, and had wide enough response to register efficiently also the greenish h-beta light, though not very much of the stronger red light, the Balmer line for hydrogen-alpha at 656.3 nm. This new information about the wavelengths of energy emitted by the nebulae, coupled with the theories of Edward E. Barnard that were shortly to be unfolded, were the raw material that would later enable modern astrophysicists to categorize the clouds of nebular matter, both glowing and dark, that populate interstellar space.
A great tradition of amateur accomplishment had long existed in the British isles, probably stemming from the days of medieval nobility, when a proper courtier could strum the lute and rhyme a couplet with the best of his peers, though his business may have been tax-collection or soldiering. The prosperity, stability, and morality of Victorian England had encouraged intelligent men of property to devote their private energies to the advancement of knowledge, and the many literary, social, and scientific societies welcomed the contributions of amateur and professional alike (of course, a Doctorate or Knighthood after one's name could not hurt the chances of a dabbler!) So accomplished were the observers Admiral W. H. Smyth and Reverend W. R. Dawes, and the telescope makers William Parsons (Lord Rosse), William Russell, James Naysmyth, and Ainslee Common (builder of the original version of Lick Observatory's first reflector instrument) that the arbitrary distinction between professional and amateur was scarcely relevant.
Pioneering Astrophotographer Dr. Isaac Roberts, courtesy of Mary Lea Shane Archives of Lick Observatory
Such a brilliant man of means was Isaac Roberts. Born in North Wales on January 27, 1829, the six-year-old Isaac was brought to Liverpool to reside in the dark, self- deterministic industrial environment chillingly depicted in the stories of Charles Dickens. Whatever instruction Isaac received was from his father or in the strict Welsh Calvinistic Sunday schools, guaranteeing that he would revere both hard work and the craggy Welsh language, cultivated by him to the end of his life. (158)
As a teenager Roberts was apprenticed to a contractor, learning the skills of building so thoroughly during his 13-hour workdays that he became not only a master craftsman, but also the president of the Master Builder's Association; every spare moment was given to the study of science, favoring chemistry, geology, electricity, microscopy, spectrum analysis, meteorology and -- yes -- astronomy. (157)
Becoming a builder of renown, Roberts acquired a large fortune which could bankroll his technical hobbies. Geologic researches at first interested him, so he undertook a series of ingenious subsurface acqueous experiments; the effects of barometric pressure and the gravitational attraction of the Sun and Moon were taken into account (158), which perhaps led him into a serious pursuit of astronomical studies.
''In devising experiments he had few equals; the idea was worked out on paper, and nothing remained but to reduce it to practice", recalled his secretary W. S. Franks (159) in Roberts' 1904 Popular Astronomy obituary. (160) A 7-inch aperture refractor but whetted Roberts' appetite for knowledge of the skies; an 18-inch reflector followed, but must not have been entirely satisfactory, for the telescope was soon presented to the Observatory at Dunkirk, Ireland.
Finally, Roberts ordered a 20-inch reflector from Sir Howard Grubb, maker of some of the finest telescopes of the era. A photographic doublet refractor was mounted on the same equatorial base, with independent movement in declination but ganged in right ascension. (161) These ''Twin Equatorials'' were to be used to provide the next great picture of the Horsehead nebula some fifteen years later.
A more perfect mirror was eventually supplied by George Calver in 1888; his superb 36-inch mirror -- made for Common's great reflector -- is still used today in its rebuilt form as the Crossley reflector at Lick Observatory. (162) Despite its smaller aperture, Roberts' new 20-inch telescope was an enormous advance over the contraption of Ainslee Common and previous British amateurs' reflectors. Roberts busied over the finest of details, sending Sir Howard Grubb repeatedly back to the drawing board to refine the performance until the mount was so stable that even if banged with the hand it would not vibrate; the flexure in all positions was to be less than 2 arcseconds, and the clock-drive so accurate that a 6th-magnitude guidestar would stay precisely in the guidescope crosshairs at 150 diameters of magnification for as long as three minutes before manual corrections were necessary. (163)
Until after 1893, the official British government's Royal Observatory at Herstmonceux Castle, Greenwich, could not match the power of Roberts' reflector (164); so the master-builder would turn his great organizational skills and determination to the enormous project of producing a complete photographic atlas of the skies from England's latitudes, a most difficult task considering the weather. But he abandoned his plan when learning at the International Photographic Convention in Paris that eighteen of the world's leading observatories were to undertake such a project. (155)
The "great nebula in Andromeda" (M-31, now known as a galaxy, and designated also as NGC 224) photographed by Dr. Roberts in 1887, and printed in Isaac Roberts' Atlas in 1928 - from Lick Observatory historical collection.
Despite enormous efforts by French astrophotographers attempting to produce their share of the 20,000 plates needed for the survey, the group's great ''Carte du Ciel'' was never completed (166); astrophysicists can be grateful for Isaac Roberts' alternate project, photographing the sky's nebular objects. Even his earliest efforts netted a useful discovery, the first photograph of the spiral shape of a nebula in his plate taken on October 10, 1887 of the "great nebula in Andromeda" (167) now identified as the nearest mighty galaxy to our own Milky Way, some 2,300,000 light years distant.
Finding the climate of Maghull, England, too unpredictable for such delicate work requiring very long exposures, Roberts dismantled his observatory and moved it to Crowborough Beacon in Sussex, 800 feet above sea level and said to offer the finest astronomical site in the British Isles. (168) In 1892, Roberts was awarded the honorary degree of Doctor of Science, preceded by the Fellowship of the Royal Society and other distinctions: thus the letters F. R. S., F. R. A. S., F. G. S., D.Sc. after his name, credits so dear to the hearts of honors-conscious Englishmen of the Victorian and Edwardian eras! (169)
The preceding biography is standard reference-book material of the life of a scientific man. But let us now inject a little color into the story of this solid citizen, and turn to a florid newspaper article of 1901 from the Mary Lea Shane archives of Lick Observatory. The headline blares, ''How Dorothea Klumpke, the Astronomer, Was Won at Midnight, While studying the Stars in a Balloon, by a Fellow Scientist." (170)
The young Dr. Dorothea Klumpke, courtesy of Mary Lea Shane Archives of Lick Observatory
In breathless but circumspect prose, the gushing article discloses ''the engagement of Miss Dorothea Klumpke, the most famous woman astronomer in the world. She was wooed and won in a balloon. Her fiance is Dr. Isaac Roberts, a well-known English astronomer, seventy-two years old." The article reflects the proprieties of the time in not adding that Miss -- rather Dr. -- Klumpke was 32 years his junior, and that it would be Roberts' second marriage.
Isaac Roberts was described as being, despite his years, ''still physically as well as intellectually vigorous. He is a short, thick-set man with a thick white beard." The two met at the 1887 Astrophotographical Congress in Paris, where Admiral Mouchez had received and publicized the first experimental astrophotos by William H. Pickering, an imperfect, nascent image of the nebular region near Zeta Orionis that was to be considerably superceded by 1888! (171)
A selection of quotations will provide the genteel flavor of turn-of-the-century romanticism inherent in the newspaper account:
''Dr. Roberts was deeply impressed by the excellence of her photographs of the heavens. He himself was engaged in this kind of work in England and he was much impressed by the superiority of his feminine rival in France. He began an exchange of photographs with her -- photographs of the heavens, of course.
"He learned to admire her not only as an astronomer, but as a woman. Gradually a courtship began in the picturesque Paris Observatory, where Miss Klumpke holds a very important position...observing and recording the stars in the Paris belt. She is one of the most accomplished photographers of stars. ln the pursuit of this work she has been accustomed to go up in a balloon. She is an absolutely fearless aeronaut...
"...It was on one of these ascents that he at last found time to propose. Parisian friends and admirers of Miss Klumpke thus describe the scene: was a gorgeous night, with myriad stars shining clearly in the heavens. Below were the twinkling lights of Paris faintly indicating the outlines of houses and buildings. The balloon was sailing through the pure and silent upper air. The charming astronomer, her evening's work done, lingered with her hand on the telescope to meditate and enjoy the beauty of the scene.
"It was the psychological moment. She was gently aroused from her reverie by the pleading of her learned companion. She remembered his worth and his devotion. He won his cause. Hereinafter the two astronomers will share their study of the stars.
"It is a significant fact that Venus was the star which Miss Klumpke was chiefly observing when this romance occurred. The superstitious will immediately draw their conclusions from that. The moon was also photographed, but whether that hid any influences one would hardly venture to say." (172)
(Despite author Waldee's repeated written entreaties to the Paris Observatory, as well as a request on his behalf in person at the Observatory by Shiloh Unruh, no one at the august institution seemed able -- or willing -- to produce any examples of said pictures! Her 'photographs from a balloon' were probably newspaper hyperbole, comparable to "John Herschel's observations of creatures on the Moon" in the 1835 New York Sun.)
Dorothea Klumpke was born in San Francisco in 1861, and lived a long and productive life until her death in 1942. Dorothea's father John Klumpke was a Dutch settler who prospered in the territory of California; his fiance Dorothea Mathilde Tolle was intelligent and accomplished. As their family grew, the Klumpkes bucked the tradition of the times by raising their four daughters to be as well-educated as their son: favoring the schools of Germany and France. (173) Young Dorothea and her three sisters were an extraordinarily gifted quartet, who distinguished themselves in the breakthrough period just before the age of women's suffrage.
Anna Klumpke became an acclaimed artist in France, eventually inheriting the enormous property and art treasures of her mentor Rosa Bonheur. Augusta Klumpke was a distinguished physician; the youngest sister Julia became the most accomplished pupil of the celebrated violinist Eugene Ysaÿe. The four chose to live and work in Paris, enjoying the chateau and wealth inherited from Rosa Bonheur and gathering around themselves a ''charmed circle'' of French society, mad about the famous American emigrees.
Dorothea gave up an early ambition to become an operatic prima donna for an academic career, eventually earning the first doctorate in mathematics awarded to a woman in all of France, her thesis entitled "A Contribution to the Study of the Rings of Saturn.'' Her brilliance enabled Dorothea quickly to dispatch fifty competing Frenchman for an appointment to the Paris Observatory, where she came to head the department of computation. The newspaper account of her engagement continues with a typical contemporary attitude of condescension, seemingly amazed by the possibility of a woman being capable of such accomplishments, referring to her as a maidenly ''Miss'' rather than as a scholarly ''Dr.'':
''In spite of her profound scientific [accomplishments] Miss Klumpke is of pleasing appearance and dresses quite tastefully... She has a special bureau of her own in the great observatory garden, and it is covered with ivy and surrounded by flowers. Here Miss Klumpke works eagerly from 9 in the morning until 5 in the afternoon, and at night she stays up in the round tower with her telescope turned searchingly upon the stars, or goes up in a balloon to study them better. Her whole life is bound up in her work. She delights in it, and the heavens to her are as intimate as the little garden of her bureau, where the snails crawl over the paths and the French roses bloom." (174)
Isaac Roberts was lucky in his match, having acquired as his second wife a professional woman of intellectual distinction who, after his death, would promote his work and continue to analyze and publish the photographs produced at his observatory; the present author found many of Dorothea Klumpke Robert's submissions in early 20th century editions of the Astronomische Nachrichten and Royal Astronomical Society bulletins. For the last 13 years of Dr. Isaac's life, thousands of plates of stars, nebulae, and clusters were taken at ''Starfield'', many to be published at his own expense and distributed in two large volumes to observatories and libraries around the world. (175)
A special project that provides us with the next celebrated Horsehead photograph is described at the conclusion of Roberts' biography: it was nothing less than an attempted photographic confirmation of William Herschel famed '52 nebulous regions'.
Just as some backward physicians had happily hacked away without adopting Lister's antiseptic methods, conservative ''establishment'' astronomers at the end of the 19th century continued to pursue obsolete visual astronomy rather than submit to the difficulties of early astrophotography; indeed, a naked-eye study of the Milky Way was stimulated by the work of Bonn astronomer F. W. A. Argelander, who called for amateurs to contribute to the knowledge of zodiacal light, variable stars, meteors, and the clouds of the ''Milchstrasse.'' (176) In the very year that Barnard began his Willard lens photographs, the German astronomer Otto Boeddicker (previously the assistant to Lord Rosse) published his map of the Milky Way, described by Joseph Ashbrook as a ''striking rendition notable for its many faint, narrow branchings." (177) Since they are not generally available in modern reproductions, these early charts produced from visual observations can apparently only be appreciated by examining the originals, for their typical contemporary engravings lost most of the detail and realism. Thus, astronomers not having the benefit of excellent dark skies and large instruments could still scarcely appreciate Herschel's nebular regions. Isaac Roberts' photographic work would be of benefit, though as we shall see, at first in a negative manner to confirm the skepticism of the old-guard.
Dr. Dorothea Klumpke Roberts, courtesy of Mary Lea Shane Archives of Lick Observatory
Another newspaper account in the Mary Lea Shane archives preserves the tale of the sad and unexpected demise of Dr. Roberts, some three years after the happy marriage to his astronomical soul-mate Dorothea Klumpke. Told in the style of the era, the often disconcertingly grisly details bear repeating as another example of bygone journalism:
''Mrs. Roberts, deceased's wife, stated that her husband had suffered from bronchial catarrh on several occasions, and had been advised not to spend the winter in England...He had remarked twice to her, however, that he thought the excessive heat was just as injurious to his health as the cold weather. On Sunday morning he rose at his usual hour, five o'clock, and after indulging in a little Sandow exercise, as was his custom, partook of breakfasts which he appeared to enjoy...She left her husband in the summer house for a short time, and when she was returning she met him coming towards the house. He said that he thought he had better go to his room as it was cooler, and he went to lie down on the bed...When she returned to the bedside she found the doctor's face was congested, and slightly purple. She applied hot flannel compresses, and rubbed his temples with vinegar. Before either Dr. Valentine Griffin or Dr. Basden arrived, however, death had taken place.
"William Sadler Franks, astronomical assistant to Dr. Roberts, said he thought the deceased had been gradually breaking up for some time, as he had noticed him growing more feeble, but he apprehended nothing immediate.
"Dr. Valentine Griffin, who made a postmortem examination of the deceased, said that he found the heart remarkably fatty and enlarged, and all the valves incompetent on account of the fat. Death was due to failure of the heart's action, resulting from fatty degeneration and mitral incompetence, accelerated by the heat...The Coroner...remarked that nothing could be more affecting to him than the simple eloquence with which the end of a great life had been described.'' (179)
The author of the obituary considered it a remarkable feat that Dr. Roberts could achieve such perfect stellar photographs ''by many improvements of his own invention...to keep the telescope rigidly opposite the precise portion of the sky for several hours at a time...The value of these improvements will be seen when it is stated that in a space where Argelander, the celebrated astronomical professor at Bonn, registered 38 stars, Dr. Roberts obtained the impression on a photographic plate of 1,270 stars by keeping his huge reflector exactly opposite the same space for an hour and three quarters.''
Argelander's famous Bonnner Durchmusterung star chart of 1863 had included over 300,000 stars down to magnitude nine, and had been accomplished visually by means of a 3.1 inch aperture refractor. (179) Such was the advance of astronomy through photography that merely one plate of Dr. Roberts would show some 20,000 stars ''where the eye, even with the aid of a telescope, could not see a single star...'' (180) At the beginning of the 20th century, the celestial photographs of Dr. Isaac Roberts were the among the finest wonders of modern astronomy; yet the amateur astronomical education of this ''somewhat original type of character'' who ''cared little for orthodox theories'' (181) had not equipped the honorary Doctor with the prescience to theorize alongside the likes of a Wolf or a Barnard. Despite his gaffes, Roberts was certainly enthusiastic and forceful, probably much in the manner of the American Percival Lowell.
James Keeler, esteemed spectroscopist and second Director of Lick Observatory, attended the presentation of a paper by Roberts to the British Association for the Advancement of Science in Liverpool in 1896. As recounted by Dr. Donald Osterbrock in his informative and thorough biography James E. Keeler, Pioneer American Astrophysicist, the brilliant young American must have found Roberts' rather far-fetched and unsupported theories on the evolution of stellar systems to be ludicrous, especially when his lantern-slide examples were merely chance asterisms that Roberts had mistaken for significant stellar groupings. Yet Keeler was an attentive student of the beautiful images of stars and nebulae, and he no doubt came away convinced of the future promise of large reflectors. (162) Keeler's determination in struggling to perfect the old telescope of Dr. Common when that contraption finally came to reside at Lick Observatory may thus have been to some degree a legacy of Isaac Roberts.
Kevin Krisciunas, on the staff of the Joint Astronomy Center in Hilo, Hawaii (and himself a Lick Observatory graduate student in the mid-70s) states in his witty and lucid book Astronomical Centers of the World that: ''The present-day Bible of astronomy is the Astrophysical Journal, a journal which so much embodies the cutting edge of astronomical research that some astronomers would define the properly equipped astronomical library as having two copies of the 'Ap J' and no other technical journals whaksoever!'' (183) Founded by George Ellery Hale as originally a professional astronomical supplement to the well-known amateurs' periodical The Sidereal Messenger (184), by the time it stood alone as a separate publication, the Journal came to be the authoritative voice of America's new astronomy, with Hale and the tragically short-lived Keeler, both astrophysicists of utterly modern points of view, charting the editorial content.
Though articles in the earliest days, as we shall later see, may have occasionally touched on the employment of visual techniques in astronomy and spectroscopy, the Astrophysical Journal especially welcomed photographic researches, and would in future years publish the remarkable pictures of the Horsehead nebula by Roberts, Barnard, and John C. Duncan that are reproduced in this current website of 'The Horsehead Project'.
Even the earliest of such pictures was printed with the highest quality that could then be achieved by means of the half-tone process, so relatively little is lost, compared to the crudeness of reproduction given to Max Wolf's work in 1891.
It is likely that Roberts had read E. E. Barnard's reprint of Herschel's table of nebular regions in an 1892 issue of the British science publication Knowledge, with the suggestion that they would be of value for ''those interested in photographing such objects." (185) The magazine's editor was Arthur Cowper Ranyard who, as a friend of Lick Director Edward S. Holden, was among the first to receive copies of Barnard's very early experiments in photographing the Milky Way. On June 11, 1890, Ranyard replied to Holden that:
''The more I studied the beautiful copies E. Barnard has sent, the more curious things I see, which evidently cannot be photographic defects...the evidence these photographs afford of the existence of dark areas in space is most interesting. Why should we not have opaque areas as well as luminous areas?" (186)
At first, Barnard did not agree with these comments and some later editorializing by Ranyard but eventually as we shall recount, both observations and scientific logic were overwhelmingly on the side of this viewpoint, and against the Herschelian concept of ''holes''.
Dr. Roberts would find a ready publisher in Ranyard, and no fewer than 33 articles detailing the achievements of Starfield Observatory would be printed in Knowledge between 1895 and 1903, most of them superbly illustrated with high quality collotype prints (as may be affirmed by the present author, who examined numerous issues in the Lick Observatory archives.) (187) But probably because of its detailed, specific nature, Roberts' report of his systematic photography of Herschel's 52 regions appeared not in the general publication of Ranyard but virtually simultaneously in the professional journals Astronomical Nachrichten, the Monthly Notices of the Royal Astronomical Society, and the Ap J , (188) shortly after Dr. Roberts' presentation to the Royal Society of his paper on the subject.
In what must have been a subtle expression of pique, Roberts' article entitled ''Herschel's Nebulous Regions" appeared early in 1903 in the Astrophysical Journal with a footnote attached: ''The manuscript of this article was accepted by the editors on the supposition that it was not to be published in other current journals." Clearly, the Doctor had a flair for publicity, but at least this case he may have pressed to much, for as we shall see the Ap J got its revenge! Roberts explains (without crediting the suggestions of Dreyer or Barnard) that no systematic effort of verifying Herschel's 52 regions of nebulosity had been undertaken until work was commenced at his observatory, using two telescopes, the 20-inch reflector and a 5-inch Cooke triplet portrait lens. Duplicate 90-minute exposures were made by both instruments, on plates that had been tested for sensitivity (though Roberts does not explain how) so that stellar images would be recorded (he claimed) down to the 17th magnitude by the f/5 reflector and 15th magnitude by the small f/4 refractor. He boasts,
''My long previous experience in photographing the heavens enabled me to judge that under these conditions nebulosity of at least the degree of faintness that could be seen by Herschel with his two- and four-foot reflectors would be shown on the photographic plates." (189)
One reads the table of descriptions following the confident introduction with increasing surprise, for in place after place described by Herschel as ''Much affected with nebulosity'', Roberts instead finds ''Sky Clear; no diffused nebulosity.'' For example, of No. 20 in the constellation of Taurus, near the ''Crab'' nebula (M-1), a Milky Way region found by Herschel to be ''Very Much Affected'', Roberts reports ''Sky clear; stars small and very few on plate; large areas void of stars; no nebulosity.'' (190) Of course, today's amateur astronomers may see the glowing glories of Herschel's star-studded regions with small ''richest-field'' instruments under dark skies, and photograph them with results that shame Roberts with instruments of a fraction of the Britisher's telescopic aperture (as amateurs in New Mexico have done: see this page for a '60 second' exposure.) The fact that many of Roberts' plates fail to record the northern Milky Way does indicate that despite his assertions, his techniques were not necessarily always more sensitive than the visual perceptions of William Herschel -- though, indeed, it was Roberts who managed to achieve a nice exposure of the Horsehead, albeit with a subtle diminution of the general background glow that Herschel had perceived by eye, though he'd missed the 'dark cloud'. Whereas, the smaller scale image produced by Barnard in 1894, with a much more modest instrument, had definitely registered the h-beta radiating wavelength of nebula IC-434.
With hindsight we might consider the crowning achievement of Isaac Roberts in making his work known in this 1903 article to be the truly epic photograph of nebulosity south of Zeta Orionis. Of Herschel's region No. 25, categorized by the great earlier observer as merely displaying "Diffused Milky Nebulosity'', Isaac Roberts presents a veritable essay of description:
"Sky clear; stars very numerous on p. half of plate, but few on f. half, where there are large areas void of stars; large cloud of nebulosity p. f. Zeta Orionis with broad division void of stars, but with some nebulosity in s. f. to p. direction [NGC-2024]; other divisions break up the cloud into separate masses. To the s. of Zeta is a stream on nebulosity, 54 minutes of arc in length, with an embayment free from nebulosity dividing it in halves....''
If Roberts' exposure had been sufficient, it would have been immediately apparent that the "embayment" did not, in his words, divide the nebula "in halves". On Barnard's earlier plate, as on modern photos and digital images, this is readily observed.
After a lengthy description of the other nebular phenomena in the area, including NGC-2023, Roberts resumes with:
''The region here referred to, which covers four square degrees of the sky, has so many relatable features that is necessary, order to make it intelligible to the reader, to present the photograph annexed alone with the above description." (190)
Herschel's Nebulous Region No. 25 (IC-434 and Horsehead), 90-minute exposure, Isaac Roberts' Starfield Observatory, January 25, 1900; by permission of the Astrophysical Journal
To view in negative mode, click here
Perhaps even partly due to the insufficient exposure time, the photograph of the Zeta Orionis region on Plate IV in the article -- shown above -- has such delicate beauty that it defies the above matter-of-fact recitation. Though not recording the full extent of IC-434 that even young Ryan Wood achieved in 1989 with a 2.8" aperture telescope, the January 25, 1900 plate -- you see, still temporally exactly within the 19th century, and thus pertinent to this article! -- at last captures the clear shape of the 'noble head of the steed' in sharp outlined contrast against the soft stream of light. The bewildering complexity of the "Flame" (later, called ''Tank tracks'') nebula NGC-2024 probably can never be quite so clearly delineated with the 'live' human eye: even through a telescope of far greater aperture, employing the narrowest-bandpass filter. The good Doctor, at least on this field, has done his work well: in matters of aesthetics, if not with respect to the optimal collection of data.
(Please do remember that though the exposure time was somewhat shorter than the ideal, the film emulsion of the time was mostly blue-sensitive: so the glorious expanse of red-wavelength hydrogen-alpha radiation simply could not be captured by this era's astrophotography. What you have, here, is -- in effect -- something rather similar to what an amateur astronomer of today might see by eye of the character of IC-434 and the Horsehead, with a comparable telescope aperture size, a very wide field ocular, and a hydrogen-beta nebular bandpass filter.)
Succinctly summing up what he felt to be his conclusive results, Roberts avers that in 48 of the 52 regions there is no extended milky nebulosity as demonstrated by his plates! Since the ApJ had not previously shied from controversy bordering on personal insults in publishing the contested opinions of W. W. Campbell of Lick Observatory and Professor J. Scheiner of the Potsdam Astrophysical Observatory on a debated issue of spectroscopy in 1898, its editor George Ellery Hale was not about to let the matter drop without comment from the leading American expert on the Milky Way, Hale's Yerkes colleague Edward Emerson Barnard.
Compared to the Campbell-Scheiner dispute (to be detailed later), the Roberts-Barnard discussion was respectful, though no comments in rebuttal to Barnard by the elder man -- if any existed -- were published by Hale. The younger American astrophotographer summarizes Roberts' negative results in 48 out of 52 instances, finding that the 4 regions found to be nebulous on the Sussex plates had already been widely known to be so; in particular, Barnard credits Max Wolf with the photographic discovery of the ''North American Nebula'' in Cygnus, and W. H. Pickering with the first photograph of the ''curious nebulous ribbon extending southward from Zeta Orionis'' (containing what we now, of course, call the Horsehead.)
In a paragraph perhaps more prophetic than he himself might have suspected, Barnard wrote:
''This question of large areas of diffused nebulosity in the sky is a very important one, not yet fully appreciated, but which must sooner or later have the highest bearing on a proper understanding of the universe. Dr. Roberts' negative results are so sweeping in character that it is highly important that anything tending to prove any of these questioned regions of nebulosity should be brought forward at once." (191)
Barnard then makes two very telling points. First: that 90 minutes is not -- at that stage of technology -- a sufficient exposure time (even if point-sources of stellar light of as faint as 17th magnitude are recorded) to secure extended nebulosity, which is "on an entirely different footing in photographic technique than capturing images of stars..." Second, he adds that "it is a little unreasonable to suppose that Herschel, who made so few blunders compared with the wonderful and varied work that he accomplished, should be so palpably mistaken in forty-eight out of fifty-two observations of this kind." (192) Gerrit Verschuur would insist that Barnard was excessively reverent to Herschel's beliefs in 'heavenly holes,' (193) but at least in this instance, faith in Herschel was reasonably well-founded.
Yet, even after later astronomers "confirmed" Herschel's 52 nebulous fields, modern conclusions aren't quite so affirmative. The very deepest sky images are often full of traces of what are commonly called 'galactic cirrus': streaks of dust that may or may not be visible to the live eye in a large telescope. This writer has seen many instances of the same, and has been impressed by the phenomenon in the clear high-altitude air near the California Pacific coast; while certain old survey photos record relatively little, in emulsions whose peak visual-wavelength sensitivities do not precisely match the eye. Instrumental reflections in large telescopes can either mask the true effects, or conversely generate confusing phantoms (such as in the case of "Baxendell's Unphotographable Nebula": see here.)
The noted galaxy classification expert Dr. Harold G. Corwin, Jr. -- a scientist whose entire career has been involved in the intense scrutiny of photographic images -- remarked to this author that while Herschel had been correct about the diffuse nebulosity in a few regions, and got some "'right' [he] was misled one way or another for the others." But, even in Barnard's time, the American's reverent attitude toward the great 18th century astronomer -- his acceptance of "argument from authority" -- contrasts rather strikingly with the irreverence of his elder counterpart and colleague in the British Isles: closer to Herschel in geographics and culture, and perhaps not as much over-awed. Certainly it would be in keeping with Roberts' expansiveness and ambitions to demonstrate that he was not shy about asserting that he had 'debunked' the old fellow. Basing impressions on the endlessly lionizing accounts of Roberts' work from publications around the turn of the 20th century, might not one imagine that the wealthy and socially prominent engineer- industrialist / turned astrophotographer, a modern-minded, cutting edge 'expert' who took credit for the technical design of his telescopes and cameras, promoting his observatory's output with the public relations skill of Percival Lowell -- and with a doctorate degree (albeit honorary) to "prove" he was an important scientist -- may have felt himself to be at the forefront of research, striding beyond the 'obsolete' work of the professional oboist-turned astronomer, Herschel? While Edward Barnard -- who sought fame only in a very small circle of astronomy- minded colleagues and readers -- was imbued by a deep collegial kinship with the eye-astronomer Herschel, as he really understood what it was like to spend countless nights under the cold dark sky. Indeed: photographer Barnard continued to make visual telescopic observation a part of his scientific program, studying the dark nebulae by eye and publishing as late as 1913 his acute and intelligent findings about the Horsehead's "live" visual appearance in the Yerkes 40-inch refractor.
But Barnard, a bit like Roberts, often seemed, in his urgency and passion, to be something of an egotist too; his exchanges with Holden some years back certainly demonstrated an ''I-told-you-so'' tendency. (194) He cannot resist quoting his own suggestions for photographing Herschel's regions in the January 1892 issue of Knowledge, and honestly and correctly claims that he independently came across many diffused nebulosities -- including some of the items in Herschel's table -- in earlier days, before they had ever been photographed and proved by those other than Roberts to be nebulous.
Below: "Barnard's Loop" highlighting a somewhat denser than average region that the author finds easiest to spot by eye, from his article on visual observing of the nebula.
Barnard's rebuke needs but one outstanding example to refute Roberts: the case of the large nebular loop in the constellation of Orion, photographed first in 1889 by W. H. Pickering at Mt. Wilson (and graciously acknowledged by Barnard), and then by the Lick Observatory astronomer himself on December 1894 ''with an ordinary child's magic lantern lens", later employing the Willard portrait lens, and finally (with telling effect against the efforts of Roberts' mighty instrument) ''with a small, cheap lantern lens belonging to Professor Hale." On the night of January 17, 1903, Barnard obtained a plate of the great curving nebula that was ''clearly shown, especially the region described by Herschel...'' (195)
Roberts had reported that his photograph showed the sky to be ''...clear; stars very few in number; large areas void of stars, no nebulosity.'' Barnard agreed with Herschel's claim that it was ''affected with milky nebulosity'', finding that the loop ''is really the brightest portion of one of the most extraordinary nebulae in the sky, as shown by photographs made by two independent observers...'' (196)
E. E. B.'s last two paragraphs are devastating, countering the assertions of "long previous experience'' by Roberts:
''Just what the faintest stars are that appear on this [lantern lens] plate I am not prepared to say, not having had any chance to make a comparison with the sky; but they are certainly several magnitudes brighter than the fifteenth or sixteenth magnitude.
"It was with the same instruments described in his present paper that Dr. Roberts failed to get any traces of the exterior nebulosities of the Pleiades which have been of shown by four observers with four different instruments not only to exist, but to be not at all difficult objects." (197)
Dr. Max Wolf, candidly but with more suavity and gentleness than his rustic American counterpart Barnard, also objected to Roberts' "plates sans nebulosity"; you may read his surprised and skeptical response in the second of our Horsehead articles, in the section on Roberts' Horsehead photo, here.
Q. E. D.! What more could Roberts have said, except honestly to present his pictures and leave the hypothesizing to others? His flawed experiment had demonstrated what Dr. Donald Osterbrock has characterized, in referral to the teutonic stiffness of Scheiner and other Germans in disputing Lick Observatory results, as the inability of some astronomers to ''believe anything they had not themselves discovered...'' (198)
(In truth, the curving nebula generally called "Barnard's Loop" is exceedingly difficult to perceive in today's light-polluted skies, and now is even hard to photograph within proximity of settled population. The present author has, with richest-field scopes and nebular filters, viewed it vaguely during the preparation for this Horsehead research article, under darkest mountain-top skies, but could not seen it again after the 1991 eruption of Mt. Pinatubo for a few years. Eventually he stopped trying, but finally once again found it barely visible to him in October, 2006 (discussed at the link given by the photograph, above.)
Perhaps before Dr. Roberts could find a way to defend or verify his work, death came on July 17, 1904. After their marriage, his wife Dorothea had left the Paris Observatory and loyally devoted herself to assisting the progress of work at Starfield. (199) To commemorate the centennial of his birth, Dorothea began an extensive project to duplicate the plates on the doctor's 52 not-so-nebulous regions, at last publishing in July of 1928 more than just the previously- released few of the pictures so scorned by the late Edward Barnard, who had finally presented not only his Willard lens Milky Way photographs, but also many deeper exposures of beautiful bright and dark nebulosity made with the 10'' Bruce telescope, utterly vindicating his claims against Roberts.
The first atlas of Roberts' reflector plates preceded an eventual preparation in 1932 of a supplement of the simultaneous exposures with the small refractor, both publications being deluxe in the grandest European manner. The two exquisite boxed presentations are of course preserved in the Lick astronomical collection in the UC Science Library in Santa Cruz, and repose unceremoniously in the ''oversize'' collection in the bunker-like basement annex of the institution.
A poetic, exalted mood is effused throughout the pages of text that explain the images on the reflector plates. After the frontispiece, the touching dedication of the first atlas is made by Dorothea Klumpke Roberts to Sir William Herschel, to Dr. Isaac Roberts (with a full accounting in suffix of his impressive initials), and to her parents. In truth, Dorothea is the only professional astronomer of note in this company, and her credits as shown in small type are most impressive: formerly of the staff of the Paris observatory, Officier d'Académie, Docteur-ès-Sciences Mathématiques, Membre du Comite National Française d'Astronomie (section des Nébuleuses); even Life-Member East Bay Astronomical Association, Alameda, California, among other distinguished credits and accomplishments. (200)
Much had happened after the publication of Dr. Roberts' 1903 article. Before the appearance of the supplement, both Max Wolf and Edward Barnard had died, the world losing the two leading theorists on dark nebulae, the latter having most persuasively argued that they were real, obscuring matter in deep space. Lick's Heber Curtis had boldly upheld in debate that the spiral nebulae consisted of ''island universes'' to be fully corroborated by Hubble's and Humason's great achievements with the Mt. Wilson 100-inch telescope; photography and spectroscopy had dominated the field of astronomy, suppressing the inferior, less efficient, and often subjective results of visual observation. And thanks to its giant mountain-top telescopes and brilliant scientists, America was in the lead in astrophysics. Yet in reading through the text of the first Roberts atlas, one would scarcely imagine that these changes had been wrought in the world of astronomy.
Oddly for an American astronomer, and one who had every right to display a Northern California bias toward the Lick Observatory, Dr. Klumpke Roberts spares no effort to credit European observers with prime achievement in studying the ''nebulous regions" of Herschel. Perhaps because it could no longer be claimed that Isaac Roberts' photographs were even remotely accurate and representative of the true estate of the skies, a virtue is made of the sad fact that the doctor's plates showed so little.
In his preface to the inital atlas, Father J. G. Hagen, S. J., Director of the Vatican Observatory and collaborator with Dorothea Klumpke Roberts, explains that the initial negative result of the plates ''provoked some confused controversy because the real issue was not understood, viz. the question whether everything that can be seen can also be photographed.'' (202)
Despite Edward Barnard's extensive published theories of the obscuring nature of the non-luminous nebulae, Fr. Hagen blames the American for first using the term ''dark nebulae'' and thus -- he asserts -- promulgating the incorrect Herschelian idea of holes or invisibilities. (203) It gives the present author no little joy to refute this by copying Barnard's own words published 15 years earlier in 1913, in which he asserted to the contrary that of the ''so called 'black holes' in the Milky Way...some of them are so definite that, possibly, they suggest not vacancies but rather some kind of obscuring body...'' (203)
The most shocking denial of history -- and the experiences of comet- hunter Barnard, who had also already photographed many of the regions -- is the bald-faced (though no doubt sincere but incorrect) assertion that:
"after the death of W. Herschel, there was no astronomer who knew what the fifty-two fields appear like in a telescope...Nothing short of rediscovery could save them from oblivion.
"The rediscovery was made in Rome during the great war [World World War 1] when the night sky over the city was kept dark. Some years before, is true, small patches of obscure nebulae were known to Secchi [Fr. Pierre Angelo Secchi, an earlier Vatican astronomer who was a pioneering spectroscopist but who sadly was a supporter of the Martian ''canal'' hysteria], Barnard, and the writer: yet it was only in the complete harshness of the sky that extensive clouds were noticed in nearly all parts of the heavens.'' (204)
Here again is the Osterbrock ''not discovered with my telescope'' syndrome! It is hard to read the following my words of Hagen, having examined page after page of the Roberts Atlas that is barren of nebulosity or even faint Milky Way stellar clouds, and to remember that the results of Roberts were ostensibly to disprove Herschel:
''Then from 1920 to 1922, a series of papers was published on the subject in various languages, and the more comprehensive result of a systematic examination of Herschel's fields by means of charts, photographed from Dr. Roberts' plates, was printed in the [Monthly Notices] of the Royal Astronomical Society... all these publications were received with general skepticism and even protests from prominent astronomers... Not one of them was based on actual observation... The ease with which they were refuted is another illustration of the old rule that, between theory and observation, the latter must have precedence. Even to this day, though invited by the controversy, no observatory outside of Rome has indicated, that Herschel's nebulosities were observed and recognized."
Father Hagen explains that the current publication of Roberts' guidestars and coordinates should make observations --
''an easy matter, at least to practiced observers. It only requires some experimenting with aperture and eye piece.
"Those who hitherto have felt uncertain about cosmic nebulosities will find in the Atlas a ready means to satisfy their mind. If they recognize Herschel's fields, they have seen cosmic clouds; if not, then either the instrument is not of the right kind or the sky is not so good as that in England [! - Waldee's exclamation point, of course] or their eye is not so keen as was that of Herschel.'' (205)
The last point of Fr. Hagen probably indeed leaves out most of us mortals! The vacant Roberts star-fields now seem to be intended to prove that photography is not as effective as visual observations, presuming one has a telescope like the 16-inch refractor of the Vatican Observatory! (206)
It is really a blessing that Edward Emerson Barnard had been spared by mortality from the trial of replying to the statements of Father Hagen, for despite the old workaholic's mellowed manner, he would have undoubtedly generated a mighty voltage in his rebuttal!
This is not to disparage Dr. Klumpke Roberts' contribution. the initial Atlas and in its Supplement, she explains that her work was to select the best of the Starfield plates representative of each of the 52 regions, to present copies to Father Hagen for his 1926 visual survey, and then in preparation of the Atlases, to trace on positive glass copies a ''reseau'' or network of reference coordinates that would be used to position a master glass ''reseau'' of the Paris Observatory on top of the original Starfield glass negatives in order to secure photographic enlargements.
All of the coordinates of Herschel's parallelograms of nebulosity had to be re-computed to modern positions, relatively easy for one of Klumpke Roberts' attainments. The scales of the X and Y axes were carefully measured and marked, as were the guidestars used by Father Hagen for his visual survey. Then the outlines for the 52 regions were inked onto a copy of a beautiful half-century-old planisphere previously employed by the Paris Observatory for the observation of ''shooting stars" [sic].
Since the printer, Catala Freres of Paris, had never been engaged in astronomical work, it was necessary for Dorothea to exercise great effort in the supervision of their activities, especially in checking any possible deformation caused by the photo-mechanical process of removing the films from the glass of the original positive plates, reversing them, and placing the delicate substrates on gelatine supports for the final printing of the charts. Their excellent results were gratefully acknowledged by Dr. Klumpke Roberts. (208)
In a 1932 ''Prefatorial Letter'' to the later Supplement of Roberts' refractor plate Atlas, Dr. Max Wolf writes some strange and occasionally quaint statements (just prior to his own death some five months later) that seem to back-track from his 1903 critique (while admitting that he was not as successful as Barnard had been in every common region of the sky.) One might think, however, that the tone was merely motivated by collegial respect for the respected Klumpke; the mellowness of old age; and perhaps a nostalgia for 'the old times' when this work seemed so bold and revolutionary.
"I value the reproductions of the Camera plates, with their extensive fields, as highly as, or more highly than the charts of the Reflector plates. Such wide angle photographs will give the best help for locating and photographing the faint nebulosities which no one can photograph at this time...
"...Regarding my opinion of nebulae which you ask to know, the Herschel-Hagen Nebulae, -- I believe in the reality of these clouds.
"In my paper in... ... to which you allude, I showed that in three of Herschel's fields, I could photograph faint nebulosity; the others I did not try to photograph systematically; I tried it very much later...without success. But when Hagen found the Coma region filled with faint clouds, I was convinced of their reality, because, since my young years, have always seen the whole Coma sky hazed by foggy matter. At several places I could demonstrate, like Barnard, how bright nebulae fade off into dark ones...
"In my little book, entitled Die Milchstrasse, Leipzig, 1908, p. 47, I pointed out that 'dark masses could enter our system from two sides, from above and from below, covering step by step, gradually, more and more stars of our sky, so that our Milky Way would be the residue, only of disappeared splendor.' You see, long [ago] I almost was convinced of the existence of these faint clouds, and now hope that your Camera plates may help to reveal them all, photographically.'' (209)
Apparently, rather than accepting the growing evidence for the galactic theory of ''island universes'', Wolf still held to the notion that somehow there were encroaching dark masses that were ''entering'' the galaxy and snuffing out the glory of the Milky Way clouds. Wolf would have been disappointed had he lived long enough to examine the Roberts camera plates, for they indeed fail to reveal any more of the fields of nebulosity than did the reflector plates issued a few years earlier.
Despite Dorothea Klumpke Roberts' inclusion of the 1926 comments by Fr. Hagen that ''...Without the plates of your late husband, the Herschel Nebulosities would never have been cleared up", (209) the plates offered no new surprises. Once again, claiming a positive value from an incorrect negative result, she urges the observer to
''...take the trouble to trace on the 34 Camera plates of Isaac Roberts' Atlas and its Supplement, William Herschel's fields...and compare the [Roberts] charts...with the beautiful photographs of E. Barnard's Atlas of Selected Regions of the Milky Way... [and] the Photographic Studies of Nebulae by Prof. Duncan of Mount Wilson Observatory, and...the Photographs of the Orion Nebulosities... by Prof. Frank E. Ross of the Yerkes Observatory... also consult the pioneer work of Prof. Max Wolf of Heidelberg, of E. E. Barnard and others. These comparisons will reveal to him a wealth of information: he will perceived that the lanes, more or less void of stars, uniformly whitish or of the colour of the background on the Isaac Robert Charts correspond to the dark lanes of Barnard's photographs... and he will be eager to verify, with his telescope, these aspects of the sky." (210)
In other (sadly less reverent) words, sometimes the blank areas of the Roberts camera plates happened to correspond to the dark nebulae and to areas of diminished star populations caused by obscuring matter. Roberts might as well have intentionally underexposed his film and coincidentally achieved the same results.
In fairness to the intellectual honesty of Dr. Dorothea Klumpke Roberts, she includes the quote by her husband's former assistant W. S. Franks that:
''...the failure of photographs to show these extremely elusive objects does not, in my opinion, prove that they are nonexistent. As Herschel practically kept his eye in darkness whilst making his sweeps of the sky, he would develop a super-sensitiveness of the retina which modern observers rarely attain. Some of our keenest observers have expressed their conviction that Hershcel could scarcely be mistaken in these objects. And photography does fail sometimes to show objects that are visible to the eye especially when taken in poor light as may be seen in newspaper photos taken at night. Many red stars were missed in the Draper Catalogue that were easily visible to the eye with a 6-inch aperture telescope. As the Starfield photographs of these regions had only an average exposure of 90 minutes, that was probably too short to deal with them[.] Barnard's wonderful pictures of the Milky Way had an average exposure of about 6 hours. Nor is the English sky as good for such work as that of South Africa or the Pacific coast of America...'' (211)
She further records that M. de Kerolyr, winner of a prize for his efforts by the Astronomical Society of France in 1931, had no difficulty in perceiving Herschel's fields in his 10-inch reflector telescope:
''They are faintly luminous, fog-like, or like grayish clouds, sometimes of a brownish tint. A non-informed observer, seeing them, for the first time in the field of his telescope, would take them for terrestrial clouds, expecting them to vanish any moment." (212)
(Remember this cloud analogy: it had been an important revelation to Edward Barnard in his long search for the true nature of the dark nebulae in the Milky Way.)
The publication of the Supplement to Dr. Roberts' Starfield plates presents, compared to the prior Atlas, a more balanced view of the nature of the nebular objects, their 'photographability', and indeed the significance and shortcomings of the original Roberts exposures. The late Hagen's successor, Dr. Fr. Becker, wisely explains that the nebular fields must be studied in three ways: (1) by visual observations; (2) in photographic exposures, and (3) with star counts to prove the existence of interstellar absorption. He frankly concludes that the exposures ''have been far too short'' and notes that Karl Haidrich in Vienna has obtained with short-focus lenses and hypersensitized plates, ''distinct veils of nebulosity in regions which were hitherto considered free from nebulosity...'' And last, he recounts that Dr. Rolf Mueller's investigations at the University of Goettingen have demonstrated near Theta and Rho Ophiuchi ''a total absorption of more than four magnitudes, which is the greatest absorption-value thus far known.'' (213)
Finally we arrive at some reasonable, modern suggestions for pursuing the study of the nebular regions. The only issue that remains galling to American readers is that throughout the Supplement, the Herschel clouds (despite the work of Barnard, let alone Wolf) are now termed the Herschel- Hagen nebulosities, coupling the work of the two visual observers of the eighteenth and twentieth centuries as if no one else had intervened!
One can but turn to the pages of Roberts' pictures and be glad that the dust has now long settled. The photo of the great Orion nebula (M-42) in the first Atlas, taken with the 20-inch reflector, is especially satisfying in its delicate curvature of detail, as the relatively short exposure (for the time) did not deeply burn in the central bright regions. Superior to most previous photographs, the Roberts achievement with this object will stand until it is finally surpassed some years later by the Lick Crossley reflector, which will capture much more of the faint outlying bowl of nebulosity around the bright central region. Sadly the reproductions of the Atlas plates, here, are somewhat compromised compared to a live viewing of the original volume: for they were processed with a half-tone filter in expectation of publication in an ASTRONOMY magazine article that never materialized.
The photo of NGC-7000, ''The North American Nebula'', is rather disappointing, being dim and vague, registering little of the richness of the Cygnus star-clouds, though the remarkable ''continental'' outline is just visible. Our amateur friend Ron Wood has done better with a mere 4-inch Televue refractor; some New Mexican amateurs have obtained a marvelously detailed deep image with only a minute's exposure: see this page.
Field No. 7, showcasing the Andromeda "nebula'', is stunning. The spiral shape, faint dust-lanes of the arms, and even the hint of some of the globular clusters in the galaxy make this a real tour-de-force. A deeper exposure would have robbed the picture of its delicate delineation of the increasing density towards the nucleus. Again, Roberts' work, as the case of the Horsehead nebula, must be judged apart from the polemics that surrounded it on all sides.
The camera plates made with the 5-inch refractor sadly claim no new ground not previously staked out by Barnard as early as 1892. The plate containing Nos. 22 through 26, including the Orion nebulosities contained on Barnard's 1894 Willard photograph, is fairly comparable to the earlier Lick Observatory result, despite the fact that Roberts was employing the full 5-inch aperture, while Barnard had stopped the Willard lens down slightly to improve definition. Roberts' exposure time was thirty minutes less than Barnard's, which tells the tale. We must nonetheless appreciate the clean, round star images and excellent guiding, and be glad that such fine work could be done in England under unsympathetic climes.
All of us who love the sky can take inspiration from the loyal husband-and-wife team of Drs. Isaac and Dorothea (Klumpke) Roberts. He gave up his business for the lure of the nebulae; it was she who saw to it that every ounce of significance and value was wrung from her late husband's accomplishments, even to the extent of establishing a prize from the Astronomiche Gesellschaft for the best paper of the year on a subject relating to Herschel's 52 Nebulous regions. (214) The present author has, in fact, wondered exactly why some aspiring composer has not drawn inspiration, perhaps producing 52 etudes of varying character, commemorating Herschel's Nebulous fields?
Just after the publication of her Supplement, Dorothea was awarded her crowning honor, the election of Chevalier de la legion d'Honneur, taking the Cross of the Legion from the hands of the President of the Republic of France, according to the touching and affectionate obituary by Robert G. Aitken, Director of Lick Observatory from 1930 to 1935, seven years before Dorothea's demise in San Francisco.
In opening and closing comments of his reminiscences of Dorothea in the December 1942 Publications of the Astronomical Society of the Pacific, Aitken cried out:
''My heart skipped a beat as I stared at [D. K. R.'s death announcement] in the San Francisco Chronicle of October 6, 1942. Then I read it again, unbelievingly. Impossible! One cannot associate the idea of death with such a warm and living personality...And now she has gone from us, this great astronomer, this loyal-hearted, generous woman. But not to die. She will live on for the world at large through her work and her benefactions. In the hearts and memories of those who had the privilege of calling her their friend her rich, warm personality will abide, an everlasting presence."
THE CENTURY OF THE AMATEUR CLOSES.
It would be fair to characterize the astronomy of the 1800s as ''The Century of the Amateur", at least with respect to the pursuit of knowledge of the sky's mysterious nebulae.
Well into the era, relatively few of the non-stellar objects now of greatest interest to scientists had been studied or even seen; professional astronomers were largely concerned, throughout a century noted for its ''establishment'' conservatism, with improving visual optical equipment, increasing the size and accuracy of star charts, and perfecting the calculation of orbital elements.
Many of the innovations in the areas of discovery, technique, and theory were made by amateurs; or to be more precise, by a category of dedicated astronomers who were not employed by the national observatories or colleges, who did not have specific educational and training backgrounds in classical astronomy, and who frequently pursued their activities at their own expense. Yet the scientific attainments of many of these gifted individuals would have a revolutionary impact on celestial knowledge, still resounding in the instruments and programs at the cutting edge of today's astronomy.
Consider this list of individuals who made historic, innovative contributions during the period:
- British astronomers William and John Herschel, pioneers of the sky's "diffused nebulae";
- E. P. Mason, Short-lived American amateur and early expert on the Trifid and Veil nebulae, likely the first astronomer to develop luminance-contour or "isophote" maps;
- Reverend William Rutter Dawes, British theologian and double star observer;
- Admiral William Henry Smyth, amateur builder of a fine private observatory, who published in 1844 his Cycle of Celestial Objects, one of the first popular works for telescopic observers that provided descriptions of hundreds of deep-sky objects;
- William Parsons (Lord Rosse) builder of the enormous 72-inch reflecting telescope, the largest of the century;
- William Huggins, the pioneer of celestial spectroscopy;
- American amateur astrophotographers Lewis Rutherford and Henry Draper;
- British amateur telescope maker Dr. A. A. Common;
- British amateur double-star observer Edward Crossley, who donated Common's telescope to
- Williamina P. Fleming, the ''Scotch maid'' who as an important member of the Harvard College Observatory classified the characteristics of the stars and 'discovered' the Horsehead nebula on a plate made by the HCO;
- Edward Emerson Barnard, amateur comet-hunter turned professional astronomer and theorist;
- Sherburne W. Burham, the court-reporter who took up double-star observing;
- Percival Lowell, the brilliant Boston Brahmin who established his own Flagstaff Observatory;
- Isaac Roberts, the builder turned amateur scientist and astrophotoqrapher;
- George Ellery Hale, scion of a wealthy family who as an amateur set up his own "Kenwood" Observatory and later established the Carnegie Institute Observatories and to stimulate the building of the 200-inch Palomar Mountain telescope.
Perhaps bestriding all the others are the seminal figures of William and John Herschel, pioneers in telescope-making, deep-sky observing, and (later) the development of photography.
Many members of this distinguished group had no degrees in a discipline directly related to astronomy; some barely acquired a bachelor's degree or had no college education. Few had Ph.D.s; even at Harvard College Observatory as late as 1884, only one staff member had attained more than a master's degree; not even Director Pickering had a doctorate! (216) A minority were ever professionally employed in ''establishment'' astronomy; some achieved their greatest accomplishments strictly as amateurs. Many of the wealthy in the group set up their own private observatories to pursue their interests and whims.
Well-trained 19th century scientists who made important contributions, such as Joseph Fraunhofer and William Huggins, were certainly not amateurs in the field of physics, but they were definitely not professional astronomers: astrophysicist and professor Martin Harwitt has described a sociological study by David Edge and Michael Mulkay that calls such contributors 'marginal workers'. ''Prior to 1954," writes Harwitt, "half of all astronomical discoveries were made by outsiders." (217)
Had these individuals (even if they had somehow attained the accepted qualifications) been forced to work under the direction of a boss like the notoriously hidebound British astronomical authority-figure Sir George Airy, our science would have taken a different and much longer and slower course!
Sadly, there are but rare opportunities today for an amateur astronomer to make similar important and lasting contributions to the field. It is no longer generally possible to set up a small private observatory at one's home in a light-polluted metropolitan area and to discover objects never seen before (though my acquaintance, Mr. Richard Crisp, is trying to prove the exception!), just as it is not possible, in the era of the Hubble Space Telescope, for an amateur to build the world's most powerful instrument for studying the skies. As 20th century science rolled in at a rapidly accelerating pace, professionals would now possess the resources to carry forward the study of the mysteries of the nebulae, successfully resolving many of the basic questions raised by the pioneering amateurs of the 19th century, who were 'in the right place at the right time'.
A chronology of 19th-century events relating to the exploration of the ''diffuse nebulae'', including the discovery of many basic principles and techniques of observing, photography and spectroscopy, will be instructive in demonstrating the proportion of amateur contributions. The points of reference are, of course, the issues bearing closely on studies of the Horsehead, conveniently closing the century on its hundredth year with the photograph by Dr. Isaac Roberts. Annotations will provide useful sources of articles for further study of the individuals and events.
A ''HORSEHEAD'' CHRONOLOGY OF RELATED 19th CENTURY ASTRONOMICAL EVENTS
1802. British chemist William H. Wollaston discovers that the dark lines of the sun's spectrum always keep the same relative order and position through glass of differing refractive indices. (218) Wollaston also discovers that UV or ''actinic'' rays affect photosensitive materials. (219)
1811. William Herschel's February 1785 paper ''Astronomical Observations Relating to the Construction of the Heavens'' (including the list of 52 nebulous regions) is published by Britain's Royal Society in its ''Philosophical Transactions". (220)
1814. Joseph von Frauhofer studies the sun's spectrum in detail, labelling its most prominent dark (later called absorption) lines A through K. (221)
1824. Fraunhofer's 9.5 inch aperture Dorpat refractor is in operation, featuring an equatorial mount that can track the sidereal motions for long periods, even at high magnifications. (222)
1825. John Herschel begins eight years of examinations of his father's discoveries of clusters and nebulae. (223) Czech phenomenologist J. E. Purkinje publishes in Berlin his account of differences in the eye's color sensitivity at varying levels of illumination, the so-called "Purkinje" effect. (224)
1829. John Herschel carefully studies and maps the Orion nebula with an 18-inch aperture reflector. (225)
1834. John Herschel undertakes a 3 year expedition to South Africa to extend his father's catalogue of sky objects. He records 1,707 clusters and nebulae, (226) finding more "holes in the heavens", many in the area of Rho Ophiuchi. (227)
1839. John Herschel takes the first photograph ever made on a glass plate, of his father's 40-foot telescope. (228) Herschel also finds that infra-red and visible red light affect photosensitive materials, and he experiments with photographing the optical spectrum. (229)
1840. Dr. John W. Draper makes a Daguerrotype photograph of the Moon. (230) In April. young American astronomer Ebeneezer P. Mason submits an important 49-paqe study of the Trifid, Omega, and Veil nebulae to the American Philosophical Society, being possibly the first astronomer to prepare a brightness contour (isophotal) map. He discovers a connection between the two parts of the extended filamentary Veil nebulae in Cygnus. The 21-year old Mason dies of tuberculosis on December 26. (231)
1844. Bonn astronomer F. W. Argelander publishes his "Aufforderung" (Invitation), appealing to amateur astronomers to study the Milky Way and other objects, of course by visual means. (232)
1845. Foucault and Fizeau at the Paris Observatory first photograph the disk of the sun. (233) In the spring, Lord Rosse discovers the spiral structure of the Messier ''nebula'' no. 51 (234)
1849. Leon Foucault demonstrates that the bright lines of incandescent sodium's spectrum as observed in the laboratory coincide with the dark ''D'' lines of sunlight. (235)
1850. On July 18, America's John A. Whipple and W. C. and G. P. Bond employ the Harvard Observatory 15-inch refractor to make the first stellar photograph, of Vega. (236)
1857. Whipple and J. W. Black begin taking photos of the Moon by the new wet-plate process. (237)
1859. German astronomer Ernst Wilhelm Tempel claims the visual discovery of nebulosityaround the star Merope in the Pleiades open cluster. (238) The German spectroscopist Gustav Kirchhoff publishes his report on spectral analysis; he and Robert Bunsen determine in examining the ''D'' line of sodium's spectrum that the sun has an atmosphere containing sodium that absorbs the light of this wavelength. (239)
1862. The German astronomer Arthur Auwers revives W. Herschel's list of 52 nebulous regions, reprinting it in Koenigsberg (240) in a reduction to epoch 1830. (241)
1864. On August 29, Britain's William Huggins employs the spectroscope to visually study a planetary nebula, seeing just one emission line; some nebulae are thus found to consist of luminous gas. (242) Sir John Herschel's Catalogue of Nebulae and Clusters of Stars is published, containing 5,079 objects discovered primarily by the Herschels. (243)
1866. New York amateur Lewis Rutherford photographs the Pleiades on February 21, recording stars to 8th magnitude but not capturing the nebulosity. (244)
1867. George P. Bond's study of the Orion nebula from 1864-67 using the Harvard College Observatory's 15-inch refractor is published, including his superb drawing. (245)
1866. William Huggins determines the radial velocity of Sirius, though not the accepted modern figure, by measuring the Doppler shift of the ''F'' line of hydrogen in its spectrum. (248)
1869. Sir John Herschel visually confirms the discovery by Lord Oxmantown of a continuous spectrum in the light of the Orion nebula, postulating the existence of a series of nebulae from pure continuous-type to pure emission-type. (247)
1872. American amateur Dr. Henry Draper obtains the first really satisfactory photograph of a stellar spectrum, recording 4 lines in the spectrum of Alpha Lyrae. (248)
1875. Huggins at last photographs good spectrograms of Sirius, Vega, and other bright stars. (249) spectrograms of Vega, 1878. Charles H. Bennett perfects the dry gelatin photographic plate, permitting faster exposures, smaller cameras, and practical astrophotos. (250)
1879. British amateur Dr. A. A. Common constructs his 36- inch aperture reflector telescope, later to be given to Lick Observatory. (251)
1880. William Henry Pickering discovers the differences in the sensitivity of photographic plates to daylight versus gaslight. (252) In September, Henry Draper takes the first photograph of the Orion nebula, but stars visible in a 6-inch telescope are not shown. (253) Draper invents a governor to better control the rate of his sidereal clock drive. (254)
1881. American amateur Edward Emerson Barnard begins his serious pursuit of astronomy, taking up comet-seeking with a 5-inch aperture telescope; his first credited comet discovery is on September 17. (255)
1882. The amateur's publication The Sidereal Messenger is brought out by W. W. Payne of Carleton College, the first general American astronomy periodical since the Civil War. (256) The eclectic Edward S. Holden publishes his 230-page monograph on the Orion nebula, collecting all important historical accounts of observations and many drawings of note, most reproduced as woodcuts. (257) Huggins obtains a spectrogram of the Orion nebula, finding a strong emission line in the ultra-violet wavelengths. (258)
1883. Dr. A. A. Common successfully photographs the Orion nebula with his 36-inch reflector, showing stars not visible to the eye. (259) William Pickering discovers that photographic emulsions are sensitive to infra-red light. (260)
1884. The young Edward Barnard publishes an early effort. a report on observing a small black hole in the Milky Way in the German professional astronomy periodical Astronomical Nachrichten. While comet- sweeping, he finds with his 5-inch aperture telescope a dark spot in the Sagittarius star cloud that ''looks like a drop of ink." (261)
1885. French astrophotographers Paul and Prosper Henry photograph the Merope nebula in the Pleiades; when this photo is confirmed by visual observations at the Pulkova Observatory, the controversy over the existence of the nebula is ended. (262) Harvard College Observatory Director E. C. Pickering purchases a Voigtlander 8-inch aperture doublet, using the Alexander Dallas Bache funds. The lenses are photographically corrected and mounted by Alvan Clark; this instrument will take the first photograph of the Horsehead nebula some three years later. (263) Dr. Common sells his 36- inch aperture reflector telescope to the British amateur double-star observer Edward Crossley of Halifax, England. (264) In April, Isaac Roberts installs at Maghull the 20-inch aperture reflector built for him by Sir Howard Grubb. (285)
1886. Mrs. Draper presents her late husband's 11-inch aperture Clark photographic telescope to Harvard College Observatory, with funds to endow a program of spectroscopy. (266)
1887. William Henry Pickering begins his photographic program at Harvard, concentrating on the Moon, the planets, and the Orion nebula. (267) Paul and Prosper Henry photograph stars down to 16th magnitude in an 80-minute exposure with the 13-inch aperture refractor of the Paris Observatory. (268) The Astronomical Photographic Congress is held Paris; W. H. Pickering's first test photos of the Zeta Orionis region are sent to its director, Admiral Mouchez. (269) At the Congress, Isaac Roberts meets Dorothea Kumpke. (270) On October 10, Roberts photographs Andromeda, obtaining the first depiction by such means of the spiral structure of certain "nebulae", now of course known as galaxies. (271)
1888. On February 6, W. H. Pickering and the Harvard College Observatory photographic team obtain the especially good ''discovery'' plate -- B2312 -- containing the Horsehead nebula. (272) Britain's Dr. J. L. E. Dreyer publishes the New General Catalogue of clusters and nebulae. (273) ln June, Edward Barnard obtains his appointment as a professional astronomer at Lick Observatory. (274) Starting on June 27, Mrs. Williamina P. Fleming, at HCO, measures and describes all the 'new' nebulae discovered by means of W. Pickering's photos of Orion. She notes and describes the region of the Horsehead, not specifically naming it but giving a detailed description of it as a detail she defines and measures in the nebular stream catalogued as no. 434. (59)
1889. On January 1, the Willard lens is employed for eclipse photos by Charles Burkhalter of Chabot Observatory, interesting E. S. Holden in purchasing it for Lick Observatory. (275) In the January issue of Sidereal Messenger W. Pickering publishes his discovery of the great curved nebula in Orion, having photographed it at Mt. Wilson with a 2.6-inch aperture lens. (276) Miss Catherine Wolf Bruce meets E. C. Pickering and on May 30 offers him $50,000 for a Harvard photographic telescope. (277) Later she will donate funds to the Carnegie Institute for the 10-inch Bruce telescope, to be used by Barnard for his Milky Way photos and an excellent picture of the Horsehead. (278) Barnard begins testing the Willard lens at Lick, photographing the Milky Way. The first picture to be published is taken on August 1, of a region in Sagittarius near M-8. (279) The Willard lens is sent by Professor Holden to John A. Brashear for refiguring. (280)
1890. ''The Draper Catalogue of Stellar Spectra" is published by Harvard College Observatory. In a survey from 1886-9, thousands of spectra are photographed and turned over to Williamina P. Fleming for classification. Her system (based on the strengths of hydrogen and calcium absorption lines, labelling spectral types from A to O with J omitted, reserving Q for unusual spectra) is later modified by Antonia Maury and Annie J. Cannon. (281) Harvard College Observatory publishes its list of nebulae discovered by photography, included: the nebula south of Zeta Orionis containing the Horsehead, found on the plates by Mrs. Fleming. (282) On June 11, Arthur C. Ranyard -- editor of Knowledge -- writes to Lick's Director Holden that the early Barnard Willard lens test photos surely depict obscuring dark clouds, not holes. (283) Isaac Roberts moves his telescopes to Crowborough Beacon, Sussex, establishing Starfield Observatory. (284)
1891. On January 2, Max Wolf photographs the nebulosity south of Zeta Orionis, which he believes that he has first discovered. The picture does record a recognizable part of the Horsehead. When the picture is submitted to the British Astronomical Association, editor E. Walter Maunder notes that the long 'streamer' nebula S of Zeta Orionis was not a Wolf discovery, but surely had previously been photographed by W. H. Pickering. (285)
1892. In the January issue of the British periodical Knowledge, Barnard publishes William Herschel's list of 52 nebulous regions, suggesting that they be confirmed by photography. (286) German astronomer Carl Boeddicker publishes an especially fine map of the Milky Way made from visual observations. (287) Barnard begins his Milky Way and comet photographs with the re-figured Willard lens at Lick Observatory. (288)
1893. Edward Crossley ceases astronomical research, announcing that the 36-inch reflector is for sale. (289) The first volume of Isaac Roberts' photographs of stars, clusters, and nebulae is published by himself; a second volume will follow in 1895. (290)
1894. Lick Observatory makes a giant leap toward modernity in scientific analysis of the Great Orion nebula, compared to its Director Holden's 1876 monograph, by employing astrophysical investigations. W. W. Campbell visually observes the hydrogen-beta line in Orion's trapezium region; he finds differences in the strengths of 3 nebular lines across the extent of the nebula. (291) Edwin Frost translates into English and publishes in America the classic reference work on stellar spectroscopy by Germany's Dr. Julius Steiner. (292) Ranyard publishes the Lick Observatory Willard lens Milky Way photos in Knowledge, and critiques Barnard's description of ''holes", citing the improbability of such an earth-centered geometrical arrangement of regions of stellar depletion. (293)
1894, continued. On October 3, Barnard obtains an excellent 2-hour exposure with the Willard lens of parts of the constellation of Orion, containing the Horsehead nebula. (294) Also on October 3, a simultaneous photograph is made by Barnard with an f/2.3 lens of a mere 1.5-inch aperture, securing a plate of the great curved nebula around Orion, commonly referred to as "Barnard's Loop". (295) On November 2, George Ellery Hale holds the first meeting of the board of directors of the publication later to be known as The Astrophysical Journal. (296)
1895. On January 11, Dr. Dreyer reads his paper to the Royal Astronomical Society, presenting the new nebulae of his ''Index Catalogue'' supplement to the NGC, including the nebular region south of Zeta Orionis, numbered 434 and attributed to ''Pickering'', referring to E. C. Pickering, the Director of Harvard College Observatory. (297) On April 8, Edward Crossley agrees to donate his 36-inch reflector telescope to Lick Observatory. (298) Britain's Lord William Ramsay identifies the spectrum of helium in the laboratory; the mysterious yellow lines in the spectrum of the Orion nebula were seen to coincide with a line of the unknown solar element previously named ''helium'' by Norman Lockyer. (299) Isaac Roberts begins photographing Herschel's 52 nebulous regions at Starfield Observatory. (300)
1896. On June 3, the Crossley 36-inch reflecting telescope is installed at Lick Observatory. (301)
1887. On May 21, the giant Yerkes 40-inch refractor telescope sees first light; (302) much later Barnard will try it visually on the Horsehead nebula. (303) In September, the German spectroscopic Carl Runge visits Lick Observatory and confirms with the 36-inch refractor Campbell's findings on the Orion nebula's spectral lines. He submits a paper to the ApJ in May of 1989 explaining that the variations are not caused by the Purkinje effect. (304)
1898. In January, Professor Scheiner of Potsdam Astrophysical Observatory accuses Campbell and other Lick astronomers of being youthfully inexperienced, mistaking the Purkinje effect for their claims of differences in intensity of the Orion nebular lines. After his paper and Runge's defence of Campbell are published, the ApJ editors call for a resolution of the issue by photographic means. (305) On June 1, James E. Keeler assumes the post of Director of Lick Observatory, succeeding Edward S. Holden. (308) In July, Keeler publishes his first research at Lick, confirming Campbell's earlier discovery of a cloud of glowing hydrogen gas around a peculiar nebular star known as a Wolf-Rayet object; a visual spectroscope is employed on the 36-inch refractor. (307) On September 15, Keeler at last gets the old Crossley 36-inch reflector in some semblance of photographic order, making his initial exposure of the sky; (308) his project of modifications and improvements continues through 1900 as he takes many plates of nebulae. (309)
1889. James Keeler publishes in the ApJ his confirmation of Campbell's discovery of the regional variability in intensity of M-42's nebular lines, settling the dispute over the Purkinje effect. (310)
1900. In the last year of the 19th century, Dr. Isaac Roberts photographs Herschel's Nebular Region No. 25 and obtains a superb plate of the Horsehead nebula with the 20- inch reflector at Starfield. (311) Before his death on August 12, James E. Keeler has employed the Crossley reflector at Lick Observatory to photograph 104 known and 744 unknown ''nebulae'' (many now known as spiral galaxies), speculating that the 36-inch reflector could photograph as many as 100,000 such objects. Though he photographs NGC-2024, Keeler does not take a plate of the Horsehead. (312)
The 19th century was a remarkable period in astronomy, encompassing the "big bang" of the rapid expansion of scientific knowledge that shows no signs of diminishing. The men and women who contributed to that chronology of just these specific areas of astronomy related to photography, spectroscopy, and astrophysics were truly the giants on whose shoulders we researchers of the Horsehead, and other faint dark and light nebulae, must stand, including the many who personified the primary definition of an ''amateur'', paraphrasing Webster, as 'one who cultivates an art because of tastes and attainments, pursuing it for satisfaction and not for profit.'
Stephen R. Waldee (c) 1990-2006, 2012 - All Rights Reserved
Horsehead Project - Footnotes
1. Duncan, John Charles. Astronomy, a Text Book. New York:
Harper and Bros. (1926): p. 359; Hale, George Ellery. The
Depths of The Universe. New York: Charles Scribner's Sons
(1924): p. 38
2. Cederblad, Sven. ''Studies of Bright Diffuse Galactic
Nebulae.'' Meddelande Fran Lunds Astronomiska Observatorium,
Serie II Nr. 119. Lund, Sweden (1946): p. 12
3. King, Henry C. The History of the Telescope. New York: Dover
Publications (1955): p. 127
4. Gingerich, Owen, contributor to Mallas, John, and Kreimer, Evered. The Messier Album.
Cambridge, Mass.: Sky Publishing Corporation (1978): p. 1
5. Cederblad, p. 12
6. Gingerich, p. 7
7. King, p. 137
8. Texereau, Jean. How to Make a Telescope. Richmond:
Willmann-Bell (1984): p. 284
9. Vehrenberg, Hans. Atlas of Deep-Sky Splendors. Cambridge, Mass. (1983): p. 168 (after Owen Gingerich, Harvard College Observatory)
10. Herschel, Sir William. Scientific Papers (Philosophical Transactions, 1811) Editor: J. L. E. Dreyer. London: Royal Soceity and Royal Astronomical Society, Dulau & Co. (1912): p. 459
11. Herschel, p. 461
12. Herschel, p. 464
13. Herschel, pp. 464, 461
14. Bernhard, Bennett, Rice. New Handbook of the Heavens. New York: McGraw-Hill (1948) p. 324; Hale, p. 37
15. Herschel, p. 463
16. King, p. 128; p. 133
17. King, p. 136
18. King, p. 136
19. King, p. 138
20. Herschel, p. 464
21. Cederblad, p. 16
22. Hale, p. 39
23. King, p. 316
24. Newcomb, Simon. Popular Astronomy. New York: Harper Bros. (1882) p. 138
25. Wallis, Brad & Provin, Robert. A Manual of Advanced Celestial Photography. Cambridge, England: Cambridge University Press (1988): p. 3
26. Newcomb, appendix I, pp. 533-534
27. Wallis & Provin, p. 4
28. Wallis & Provin, p. 4
29. Martz, E. P., Jr. ''Professor William Henry Pickering, An Appreciation." Popular Astronomy. Vol. XLVI No. 6 (1938) p. 299
30. Martz, p. 299; McPherson, Hector Jr. Astronomers of To-Day. London: Gall & Englis (1905) p. 225. Abbott, David. Biographical Dictionary of Scientists. 1. Astronomers. London: Frederick Muller Limited (1848): p. 126
31. Sadler, Philip M. ''William Pickering's Search for a Planet Beyond Neptune.'' History of Astronomy, American Astronomical Society (to be published as of 1990, advance copy) (1990): p. 1;
King, pp. 140-141
32. Martz, p. 299
33. Abbott, p. 126
34. Martz, p. 299
35. Pickering, Edward C. (ed.) Annals of the Astronomical Observatory of Harvard College, Vol. XXXII. Cambridge, Mass.: Harvard Observatory (1895) Preface
36. Pickering, William H. ''lnvestigations in Astronomical Photography.'' HCO Annals. Vol. XXXlI-Part 1. Cambridge, Mass.: Harvard Observatory (1895) pp. 1-24.
37. Wallis & Provin, p. 13
38. Pickering, William, p. 23; Wallis & Provin, p. 223
39. Pickering, William, p. 25
41. Pickering, William, p. 80
42. Sinnott, Roger. "Gleanings for ATMs." - Editor's Note. Sky and Telescope. Cambridge, Mass.: Sky Publishing Corporation. Vol. 78, No. 5, November (1989): p. 544
43. Martz, p. 300
44. Pickering, William H. ''The Great Nebula in Orion." Sidereal Messenger. Northfield, Minn.: Carleton College Observatory. Vol. 9, No. 1. January (1890): pp. 1-2
45. Pickering, William H. HCO Annals. Vol. XXXII-Part 1 (1895) p. 5
46. Pickering, William H., p. 43
47. Pickering, William H., pp. 51-53
48. Pickering, William H., p. 57
49. Pickering, William H., pp. 61-62
50. Pickering, William H., p. 80
51. Pickering. Edward C. (Editor) (no author listed) "Detection of New Nebulae by Photography'' HCO Annals. Vol. XVIII No. VI. (1890) pp. 113-114
52. Burnham, Robert Jr. Burnham's Celestial Handbook. Vo1. 3. New York: Dover Publications (1978) pp. 1339-1340
53. Maunder, E. Walter (Editor) Footnote to article by Wolf, Max. ''Note on a Nebula Surrounding Zeta Orionis Discovered by Photography.'' Vol. 1, The Journal of the British
Astronomical Association. London: British Astronomical Association, by Eyre and Spottiswoode. (1891) p. 253
54. Dr. Martha L. Hazen, private conversation, Feb. 1990
55. Pickering, Edward C. (Editor) (no author listed) "Nebulae Discovered at the Harvard College Observatory'' HCO Annals. Vol. LX, No. VI. (1908) p. 150
56. HCO Annals. Vol. XVIII, No. VI. (1890) p. 114
57. Pickering, William H. HCO Annals. Vo1. XXXII - Part 1 (1895) p. 65
58. HCO Annals. Vol. XVIII No. VI (1890) p. 116
59. HCO Annals. Vol. LX (1908) p. 149
60. HCO Annals. XVIII No. VI (1890) pp. 116-117
61. Pickering, William H. HCO Annals. Vol. XXXII-Part 1
(1895) p. 66
62. Pickering, William H., p. 73
63. Pickering, William H. HCO Annals. Vol. XXXII - Part 1. p. 68
64. Dreyer, J. L. E. "Index Catalogues of Nebulae found in the Years 1888 to 1894, with Notes and Corrections to the New General Catalogue.'' Memoirs of the Royal Astronomical Society, Vol. LI. London: Royal Astronomical Society, Burlington House (1892-95) p. 198
65. Dreyer, p. 185
66. Dreyer, p. 187
67. HCO Annals. Vol. LX (1908) p. 149 68. Hazen, private conversation, Feb. 1990
69. Martz, p. 301
70. MacPherson, p. 228
71. Lowell, Percival. Mars. New York: Houghton Mifflin Co. (1895) Chapters II, III, IV, and Conclusion, pp. 203, 212
72. McPherson, pp. 232-233
73. Sheehan, William. Planets & Perception. Tucson: The University of Arizona Press (1988)
74. E. E. Barnard, letter to Simon Newcomb, December 11, 1894. Mary Lea Shane Archives of the Lick Observatory.
75. Sadler, Philip M., quoting from Pickering. William H., The Moon, New York (1903) p. 56
76. Pickering, William H., Reflectors Versus Refractors'' (Reprinted from Popular Astronomy, 1930), Amateur Telescope Making Advanced (Book Two). Scientific American, Inc. (1959) p. 613
77. Sadler, p. 9
78. Sadler, p. 2
79. Sadler, pp. 4-7
80. Sadler, p. 8, quoting Hoyt, Isis, CCXXXIX (1978) p. 551
81. Hoyt, William Graves. Planets X and Pluto. Tucson: The University of Arizona Press (1980) p. 214
82. Sadler, p. 8
83. Hoyt, pp. 163, 214; Bishop, Roy L. Observers Handbook 1989. Toronto: Royal Astronomical Society of Canada (1988) p. 11
84. Martz, p. 305
[note: pages for reference nos. 85-143 are misssing at this time, as of Oct. 2005 - srw.]
144. Barnard, E. E. Photographs of the Milky Way and of comets made with the six-inch Willard Lens and Crocker Telescope during the years 1892 to 1895", Publications of the Lick Observatory, XI(1913) p. 14
145. Verschuur, Gerritt. Interstellar Matters: Essays on Curiosity and Astronomical Discovery. Berlin and Heidelberg: Springer-Verlag (1989) p. 41
148. Barnard, Lick Publications, Vol. II, p. 12
147. Barnard, p. 10
148. Barnard, p. 13
149. Barnard, p. 12
150. King, p. 182; p. 186; p. 286; p. 284
151. King, p. 283
152. Abbott, p. 79
153. King. pp. 286-7
154. King, p. 289 p. 12
155. Wolf, Max, ''Ueber einege Nebelspektrem'' Astronomische Nachrichten, Band 180, January - April: Kiel (1909), p. 152
156. Franks, W. S., ''Dr. Isaac Roberts, F. R. S.", Popular Astronomy, Aug. - Sept. (1904) p. 469
157. Obituary, ''Death of Dr. Isaac Roberts, An Eminent Scientist", Southern Weeklv News, July 23: London, England (1904) Mary Lea Shane Archives of the Lick Observatory.
158. Franks, p. 470 159. Obituary, ''Death of Dr. Isaac Roberts", Crowborouogh Weekly, July 23: Sussex, England (1904) Mary Lea Shane Archives of the Lick Observatory
160. Obituary of Roberts, Crowborough Weekly
161. Franks, p. 470
182. Eugene Harland to SRW, private conversation, 2/1990.
163. King. pp. 299-300 conversation, 2/1990.
164. Krisciunas, Kevin, Astronomical Centers of the World, Cambridge, England: Cambridge University Press (1988) p. 94
165. Franks, p. 471
166. Ashbrook, Joseph, The Astronomical Scrapbook, Cambridge, England: Cambridge University Press (1985) p. 439
167. King, p. 300
168. Franks, p. 471
169. Obituary of Roberts, Southern Weekly
170. Unidentified newspaper, Oct. 3, 1901, Mary Lea Shane Archives of the Lick Observatory
171. Maunder, p. 253
172. Unidentified newspaper, Oct. 3, 1901
173. Roberts, Dorothea Klumpke, Isaac Roberts' Atlas of 52 Regions, A Guide to Herschel's Fields, La Maison de Rosa Bonheur by Thomery (1928) p. 3; Aitken, Robert G., ''Dorothea Klumpke Roberts - An Appreciation'', Publications of the Astronomical Society of the Pacific, Vol. 54 No. 321, December: San Francisco (1942) p. 218
174. Unidentified newspaper, Oct. 3, 1901
175. Franks, pp. 471-2
176. Ashbrook, pp. 373-4
177. Ashbrook, p. 375
178. Obituary of Roberts, Southern Weekly
179. Ashbrook, pp. 427-434
180. Obituary of Roberts, Southern Weekly
181. Franks, p. 472
182. Osterbrock, Donald E., James E. Keeler: Pioneer American Astrophysicist, Cambridge, England: Cambridge University Press (1984) pp. 168-170
183. Krisciunas, p. 121
184. Osterbrock, p. 186
185. Hagen, J. G., S. J., "Preface", Isaac Roberts' Atlas, p. 5
186. Letter from A. C. Ranyard to E. S. Holden, 11 June 1890, Mary Lea Shane Archives of the Lick Observatory
187. Franks, p. 472
188. Hagen, p. 5
189. Roberts, Isaac, ''Herschel's Nebulous Regions'', Astrophysical Journal, Vol. XVII, January - June; Chicago: University of Chicago Press (1903) p. 72
190. Coordinates of area: R. A. 5hr 15min 50sec, Dec. +25.1 (1900 epoch), between Beta and Zeta Tauri, Roberts, p. 74
191. Roberts, p. 74
192. Barnard, Edward Emerson, "Diffused Nebulosities in the Heavens'', Astrophysical Journal, Vol. XVII, January - June; Chicago: University of Chicago Press (1903) p. 77
193. Barnard. p. 78
194. Barnard, pp. 77-8
195. Osterbrock, Donald E., John R. Gustafson, and W.J. Shiloh Unruh. Eye on the Sky: Lick Observatory's First Century. Berkeley: University of California Press (1988) p. 94
196. Barnard, pp. 78-80
197. Barnard, p. 79; p. 78
198. Barnard, p. 80
199. Osterbrock, James E. Keeler, p. 306
200. Aitken, Robert G. The Binary Stars. New York; London: McGraw-Hill Book Company (1935) p. 220
201. Roberts, Doroktea Klumpke, Isaac Roberts' Atlas, p. 3
202. Hagen, p. 5
203. Barnard, Edward Emerson, ''Dark Regions in the Sky Suggesting An Obscuration of Light", Astrophysical Journal: Vol. XXXVIII, July-December; Chicago: University of Chicago Press (1913) p. 496
204. Hagen, p. 6
205. Hagen, pp. 6-7
206. Roberts, Dorothea Klumpke, Isaac Roberts' Atlas, p. 11
207. Roberts, Dorothea Klumpke, pp. 13-19
208. Wolf, Max, ''Prefatorial Letter '', Supplement to the Edition commemorating Isaac Roberts' Centenary, Isaac Roberts' Atlas, La Maison de Rosa Bonheur by Thomery (1932) p. 5
209. Roberts, Dorothea Klumpke, Supplement to Isaace Roberts' Atlas, p. 6
210. Roberts, Dorothea Klumpke, Supplement, pp. 7-8
211. Franks, W. S., Supplement, p. 11
212. Kerolyr, M., Supplement, pp. 13-14
213. Becker, Dr. Fr., Supplement, pp. 13-14
214. Aitken, p. 221
215. Aitken, p. 217; p. 222
210. Roberts, Dorothea Klumpke, Supplement, pp. 7-8
211. Franks, W. S., Supplement, p. 11
212. de Kerolyr, M., Supplement, pp. 13-14
213. Becker, Dr. Fr., Supplement, pp. 13-14
214. Aitken, p. 221
215. Aitken, p. 217; p. 222
216. Jones, Bessie Zaban, and Boyd, Lyle Gifford, The Harvard College Observatory, Cambridge, Mass.: Cambridge University Press (1971) pp. 189-190
217. Harwitt, Martin, Cosmic Discovery, New York: Basic Books. Inc. (1981) pp. 20-21
218. King, p. 186
219. Buttman, Guenther, The Shadow of the Telescope, New York: Charles Scribners' Sons (1970) p. 144
220. Herschel, p. 459; Ashbrook, p. 395
221. Richardson, Robert S., The Star Lovers, New York: MacMillan (1967) p. 158; Nicholson, Iain, Dictionarv of Astronomy, New York: Barnes and Noble (1977) p. 86
222. Ashbrook, pp. 24-25
223. Buttman, p. 46 224. Wright, W. David, ''The Perception of Light and Color", (ed. by Dawson & Enoch), Foundations of Science, Berlin - York: Springer-Verlag (1984) p. 257
225. Ashbrook, p. 380
226. Buttman, p. 92; Ashbrook, p. 37
227. Ashbrook, p. 396
228. Buttman, p. 84; p. 141
229. Buttman, pp. 146-147
230. Wallis & Provin, p. 2
231. Ashbrook, p. 398
235. King, p. 282
236. Krisciunas, p. 127
237. Krisciunas. p. 127
238. Moore, Patrick, Comets, New York: Charles Scribners' Sons (1976) p. 60; Chambers, George F., The Stars, New York: Review of Reviews (1903) p. 103
239. Krisciunas, p. 283; Buttman, p. 25
240. Hagen, Isaac Roberts' Atlas, p. 5
241. Cederblad, p. 23
242. King, pp. 286-287
243. Buttman, p. 185
244. Ashbrook, p. 164
245. Ashbrook, p. 385
246. King, p. 289
247. Cederblad, p. 22
248. King, p. 291
249. King, p. 292
259. Newhall, Beaumont, The Historv of Photography, New York: Museum of Modern Art (Doubleday) (1964) p. 88
251. Keeler, James, ''The Crossley Reflector of Lick Observatory'', Publications of Lick Observatory, Vol. VIII, Berkeley: University of California (1908) p. 11
252. Sadler, p. 1
253. Wallis & Provin, p. 4
254. Wallis & Provin, p. 5
255. Burnham, S. W., p. 532 [note: this recalls a reference given earlier in the lost pages; it may likely refer to an article by Burnham in Sidereal Messenger during the 1880s-90s if my memory is correct - SRW]; Fox, p. 198 [as above, recalling a lost reference, which is almost certainly Philip Fox's obituary of Edward Emerson Barnard published in Popular Astronomy in 1923 - SRW.]
256. Jones & Boyd, pp. 361-362
257. Ashbrook, p. 387
258. King, p. 293
259. Wallis & Provin, p. 4
260. Sadler, p. 1
261. Barnard, Lick Publications Vol. 11 p. 43
262. Chambers, p. 103
263. King, p. 294
264. Keeler, p. 11
265. King, p. 299
266. King, p. 294
267. HCO Annals, Vo1. XVIII, 1890, p. 116
289. Ashbrook, p. 160
269. HCO Annals, Vol. XXXII - Part 1 (1895), preface
270. Unidentified newspaper, Oct. 3, 1901; Mary Lea Shane Archives of the Lick Observatory
271. King, p. 300
272. HCO Annals, vol. XVIII, 1890, p. 114
273. Dreyer, p. 185
274. Fox, p. 197
275. Barnard, p. 12
276. Pickering, Sidereal Messenger, 1890, 1-2
277. Jones & Boyd, p. 270
278. Krisciunas, p. 168
279. (no listed author) ''Barnard's Photograph of the Milky Way'', Popular Astronomy, Vol. II (1894-5) p. 207
280. Barnard, p. 12
281. Krisciunas, p. 131
282. HCO Annals, Vol. XVIII, 1890, p. 114
283. Ranyard, letter to E. S. Holden, Mary Lea Shane Archives of Lick Observatory
284. King, p. 299
285. Maunder, p. 253
286. Barnard, ''Diffused Nebulosities in the Heavens'', Astrophysical Journal, Vol. XVII (1903) p. 78
287. Ashbrook, p. 375
288. Frost, p. 14
289. Stone, Remington, P. S., "The Crossley Reflector: A Centennial Review - I", Sky and Telescope, October (1979) p. 308
290. Aitken, p. 220
291. Osterbrock, James E. Keeler, p. 151
292. Osterbrock. p. 129
293. Verschuur, p. 42
294. Barnard, Lick Publications Vol. II, 1913, Plate 20
295. Popular Astronomy, Vol. II, 1894-5, pp. 151-152
296. Krisciunas, p. 121; Stone, p. 309
297. Dreyer, pp. 185-198
298. Stone, p. 309
299. Ashbrook, pp. 346-347
300. Roberts, ''Herschel's Nebulous Regions", Astrophysical Journal, Vol. XVII (1903) P. 73
301. Stone, p. 309
302. King, p. 316
303. Barnard, p. 21
304. Runge, Carl, ''On the Relative Intensities of the Lines in the Spectrum of the Orion Nebula'', Astrophysical Journal, Vol. VIII, June - December. (1909) pp. 32-36
305. Scheiner, Julius, ''Note on Professor Campbell's Observations of the Variations in the Intensities of the Lines in the Orion Nebula'', Astrophysical Journal, Vol VIII (1898) pp. 295-298
306. Osterbrock, p. 275
307. Osterbrock, pp. 294-295
308. Osterbrock, p. 301
309. Stone. p. 310
310. Keeler, James, ''On Some Photographs of the Great Nebula in Orion, Taken by Means of the Less Refrangible Rays of Its Spectrum'', Astrophysical Journal, Vo1. IX, (1899) p. 133
311. Roberts, Atlas, Plate IV.
312. Keeler, Lick Publications, Vol. VIII, 1908, p. 11. That there was no Keeler image of the Horsehead nebula was once again confirmed to the author by Dr. Arnold Klemola of Lick Observatory, who wrote on 23 March 2007:
Since I have certain records related to your questions about the
Horsehead Nebula (IC 434) and M 78 (NGC 2068), I attempt to give
1) Crossley plates: about 20 years ago I made a crude computer file
of Crossley plates. It is probably incomplete, as some plates were
out in personal collections. The listing gives four plates for
the Horsehead Nebula, the earliest being 1918...
In those years the Crossley plates were stored in Santa Cruz (now all
are at Mt.Hamilton). Since the Horsehead Nebula was not included in
the 1908 publication, it was likely that it had not yet been photographed...
2) As to the mystery of Keeler's authorship eight years after his
passing, there is a reasonable explanation. In a front page there
is the statement "As a tribute to the memory of James E. Keeler
director of Lick Observatory (1898-1900)". Then follows a long reprint
of a paper by Keeler from the Astrophysical Journal, 11,325,1900
(''The Crossley Reflector of Lick Observatory"). Then follow tables
and photos of objects. No other authors are given. This leaves Keeler
as sole author, despite many other objects based on plates exposed
after 1900 by others.
This investigation was undertaken by the author to determine if a Keeler Horsehead existed, since none had been found during a search of the plate vaults in 1989. Dr. Marc Pound included in his paper Looking Into the Horsehead a reference to an alleged Keeler photo of the Horsehead, citing the 1908 publication of a paper attributed to Keeler ("Photographs of nebulae and clusters made with the Crossley reflector") published by Lick Obs. in 1908. There exists an older M-78 image by Keeler, though not one of the IC434/Horsehead region, as corroborated from a search of the Lick Observatory archives by Dr. Klemola. -- srw, 7/8/12
• Update, 3/07: Click here for our companion article about another object discovered by Mrs. Fleming, IC-420, showing the original IC page that attributes these discoveries of hers from 1888 to "Pickering", as well as links to Harvard publications that properly identify the discoveries as being hers.
• Update, 7/07: We have added in the first part, recounting William Herschel's consternation about "holes in the heavens", references to the recently-published (2004, 2006) papers by Drs. Elizabeth Lada and Michael Hoskins, scholars of Caroline Herschel's scientific research, about her pioneering catalogue of dark nebulae and speculations regarding the potential importance of the "vacancies".
• For the latest news about our Horsehead research, click here for the UPDATE page.