(b. Prince Edward County, Virginia, 7 March 1837; d. New York, N.Y., 20 November 1882)
Draper’s family moved to New York City when he was two years old, and there he maintained his principal residence for the rest of his life. His father, John William Draper, was a distinguished physician and chemist. His mother, the former Antonia Coetana de Paiva Pereira Gardner, was the daughter of the attending physician of the emperor of Brazil.
Draper was stimulated to precocity by his parents and by the intellectual milieu of New York City. He swiftly rose to prominence as a gifted inventor and a deft technician who made most of his own equipment. He pursued excellence and innovation; and his principal fame rests not on his medical profession but on his astronomical avocation, pursued at his own expense. Draper maintained intellectual freedom without slipping into isolation, and he is one of America’s outstanding “amateur” scientists.
Educated at the University of the City of New York, where his father was professor of chemistry, Draper entered the medical school at the age of seventeen, after two years in college. In 1857 he had completed all his medical studies; he had written a medical thesis on the spleen, illustrated with daguerreotype microphotographs; and he had passed all of his examinations. He was only twenty, however, and since he had not yet reached the age required for graduation, he went abroad for a year with his older brother, Daniel, to relax and study.
During a visit to the observatory of William Parsons, the third earl of Rosse, in Parsonstown (now Birr), Ireland, Draper conceived the possibility of combining photography and astronomy. Returning to America in the spring of 1858, he received his medical diploma, joined the staff of Bellevue Hospital, and began preparations for grinding and polishing a speculum mirror. This tedious task occupied his spare time until the following summer, and it later ended in frustration when the mirror was split by freezing moisture. Draper’s father revealed this tale to Sir John Herschel in June 1860 and was advised that glass was preferable to speculum in ease of figuring, lightness, and brightness when silvered. By November 1861 Draper had completed the first of about 100 glass mirrors, and he installed it in his new observatory on his father’s estate at Hastings-on-Hudson, New York. His astronomical career began with daguerreotypes of the sun and the moon.
Early in 1860 Draper was appointed professor of natural sciences at the University of the City of New York, and for the next four years his teaching duties had to compete with experiments in photography and the polishing of glass mirrors. Many of these experiments were discussed at the monthly meetings of the American Photographic Society, of which he was a founding member. His monograph “On the Construction of a Silvered Glass Telescope 15-1/2 Inches in Aperture, and Its Use in Celestial Photography,” published in 1864 at the request of Joseph Henry, provided a detailed description of his techniques and became the standard reference on telescope making.
Draper’s work was interrupted during the Civil War by service as surgeon of the Twelfth Regiment of the New York State Militia. Because of poor health he was discharged in October 1862, after serving for nine months. During 1863 Draper made 1,500 negatives of the lunar face, and a small number of them bore enlargement to a fifty-inch diameter. His work was severely limited by atmospheric tremor and smoky haze, and he commented that “if the telescope could be transported to the Peruvian plateaus, 15,000 feet above the sea, or somewhere near the equator on the rainless west coast of South America, it would accomplish more.” He never reached either of these sites, but both have subsequently been utilized.
The interests of the period 1865–1867 (when he was aged twenty-eight to thirty) were interwoven through his life until his sudden death at forty-five. In this interval he published an article on spectrum analysis, completed a textbook on chemistry, and was appointed professor of physiology and dean of the faculty in the medical department. The department had just lost its building and collections in a fire; and Draper led, and partly financed, its rehabilitation until 1873, when he resigned.
In 1867 Draper married Anna Mary Palmer, the daughter of Courtlandt Palmer. Wealthy and charming, Mrs. Draper proved to be a talented assistant in her husband’s laboratory as well as a renowned hostess. The Draper dining table was frequently surrounded by celebrated scientists, politicians, and soldiers; and after Draper’s election in 1877 to the National Academy of Sciences, they regularly entertained the members during their New York meetings. During the summer months the Drapers lived in Dobbs Ferry, New York, two miles from the Hastings observatory; and each autumn they returned to their home on Madison Avenue, where Draper maintained an astronomical laboratory that acquired the reputation of being the best-equipped in the world.
Work on a twenty-eight-inch reflecting telescope continued from 1867 to 1872; it was interrupted by the ruling of gratings and by preliminary studies of the spectra of the elements, especially carbon, nitrogen, and hydrogen. As a reference scale for the determination of wavelength, Draper photographed the solar spectrum; and his results far surpassed the best spectra available from 1873 until 1881, attesting to the combined power of photography and his ingenuity.
In May 1872, as soon as the final touches had been added to the twenty-eight-inch reflector, Draper photographed the spectrum of the star Vega, but the initial attempt failed. The low sensitivity of the wet collodion plates and the difficulty of keeping the stellar spectrum motionless on the plate prevented him from obtaining more than a faint continuum without spectrum lines. By August his technique had improved, and he was rewarded with the first photograph of stellar spectrum lines. Later he devised and named a “spectrograph,” similar to Huggins’ visual spectroscope, employing an entrance slit to purify the resulting spectrum and to permit the impression of reference spectra for the identification of the celestial elements.
When his father-in-law died in 1873, Draper accepted the responsibility of managing the estate; and when he found that this job required several hours a day, he resigned as dean of the medical faculty and accepted the title of professor of analytical chemistry in the academic department. The following year he completely set aside his own research to act as director of the photographic department of the U.S. commission to observe the 1874 transit of Venus. Following the transit the commission asked Congress to order a special gold medal to be struck for Draper, and the following year he was elected to the Astronomische Gesellschaft. In 1876 he attended the Philadelphia Centennial Exposition as a judge of the photographic section.
Draper committed one significant scientific error when, in 1877, he announced the identification of eighteen emission lines of oxygen in the spectrum of the solar disk. His explanation that the emission was due to the “great thickness of ignited oxygen” revealed a failure to appreciate the significance of Kirchhoff’s law of radiation. Chemists were delighted by his announcement, but spectroscopists were at once skeptical. Draper repeated the crucial experiment at higher dispersion and carried the new results directly to the Royal Astronomical Society, but he succeeded only in sharpening the debate. After his death his contention that some apparent absorption lines were merely gaps between bright emission lines was definitely refuted by spectroscopy at still higher dispersion.
At the completion of his summer observing, Draper often hunted on horseback in the Rocky Mountains with generals R. B. Marcy and W. D. Whipple, so he was well aware of the clarity of the mountain air. He organized an expedition to observe the summertime solar eclipse of 1878; the party consisted of himself, Mrs. Draper, Thomas Alva Edison (who was able to detect the thermal radiation from the corona), President Henry Morton of the Stevens Institute of Technology, and Professor George F. Barker of the University of Pennsylvania. Their spectroscopic observations during the eclipse revealed the important fact that the corona shines largely by reflected light from the solar disk.
In the spring of 1879 Draper visited Huggins in England and learned that dry photographic plates had become more sensitive than wet collodion. He then called on Lockyer, whose work on the dissociation of the elements had profoundly impressed him. Thus stimulated, he returned to stellar spectroscopy; and in October he wrote to his friend E. S. Holden, “I have had splendid success in stellar spectrum photography this summer, having been able to use a slit only 1/1000 of an inch in width.” Draper confirmed Huggins’ discovery of hydrogen in Vega, and he noted that the stars so far observed could be placed in Secchi’s first two spectrum classes. In his report to the National Academy of Sciences that year he cautioned:
It is not easy without prolonged study and the assistance of laboratory experiments to interpret the results, and even then it will be necessary to speak with diffidence.... It is to be hoped that before long we may be able to investigate photographically the spectra of the gaseous nebulae, for in them the most elementary condition of matter and the simplest spectra are doubtless found.
The convenience of the new dry plates was wonderful; and within the next three years Draper had obtained more than eighty high-quality spectra of bright stars, the moon, Mars and Jupiter, the comet 1881 III, and the Orion nebula. His spectra of the Orion nebula revealed a faint continuous background that he attributed to the scattering of starlight by meteoritic particles.
Draper also achieved splendid and unique results in the direct photography of the moon and of the Orion nebula. The key to this success was the excellent clockwork he devised after rejecting six earlier attempts, and in October of 1880 he wrote to Holden: “The exposure of the Orion Nebula required was 50 minutes; what do you think of that for a test of my driving clock?” The following March he wrote that he had far surpassed the earlier results with an exposure of 140 minutes, so that “the singular proposition is therefore tenable that we are on the point of photographing stars fainter than we can see with the same telescope.” Draper had succeeded in making photography the best means of studying the sky, and in May 1882 he wrote: “I think we are by no means at the end of what can be done. If I can stand 6 hours exposure in midwinter another step forward will result.” He died before another winter came.
In 1882 Draper received an honorary LL.D. from his alma mater and from the University of Wisconsin. He was a member of the American Philosophical Society and the American Academy of Arts and Sciences, as well as the National Academy of Sciences and the American Association for the Advancement of Science.
In the fall of 1882 Draper resigned his joint professorship of chemistry and physics, to which he had been elected the previous January upon the death of his father. Having thus ensured himself of the free time to pursue his research, he embarked on a two-month hunting trip in the Rocky Mountains. He was exposed one night to severe cold on a mountain slope without shelter, and he returned to New York with less than his usual vigor. But plans for entertaining the National Academy of Sciences were well advanced; and on 15 November 1882 about forty academicians and a few personal friends dined at the Draper home under the novel light of Edison bulbs. Draper retired early with chills and a fever, and he died five days later of double pleurisy.
Mrs. Draper established the Henry Draper Memorial at the Harvard College Observatory to further its research on the photography of stellar spectra.
I. Original Works. Draper’s published works are “On the Changes of Blood Cells in the Spleen,” in New York Journal of Medicine, 3rd ser., 5 (1858), 182–189, his M.D. thesis; “On a New Method of Darkening Collodion Negatives,” in American Journal of Photography and the Allied Arts and Sciences, 2nd ser., 1 (1859), 374–376; “On a Reflecting Telescope for Celestial Photography,” in Report of the British Association for the Advancement of Science, 2 (1860), 63–64; “On an Improved Photographic Process,” in American Journal of Photography and the Allied Arts and Sciences, 2nd ser., 5 (1862), 47; “Photography,” in New American Cyclopaedia (New York, 1863); “On the Construction of a Silvered Glass Telescope 15-1/2 Inches in Aperture, and Its Use in Celestial Photography,” in Smithsonian Contributions to Knowledge, 14 , pt. 2 (1864); “On the Photographic Use of a Silvered Glass Reflecting Telescope,” in Philosophical Magazine and Journal of Science, 4th ser., 28 (1864), 249–255; “On a Silvered Glass Telescope and on Celestial Photography in America,” in Quarterly Journal of Science, 1 (1864), 381–387; “Petroleum: Its Importance, Its History, Boring, Refining,” ibid., 2 (1865), 49–59, and in Dinglers polytechnisches Journal, 177 (1865), 107–117; “American Contributions to Spectrum Analysis,” in Quarterly Journal of Science, 2 (1865), 395–401; A Text Book on Chemistry (New York, 1866); “Report on the Chemical and Physical Facts Collected From the Deep Sea Researches Made During the Voyage of the School Ship Mercury,” in Report of the Commission on Public Charities (New York, 1871); “On Diffraction Spectrum Photography,” in American Journal of Science and Arts, 3rd ser., 6 (1873), 401–409, also in Philosophical Magazine, 4th ser., 46 (1873), 417–425; Annalen der Physik und Chemie, 151 (1873), 337–350; and Nature, 9 (1873), 224–226; “Sur longueurs d’ondes et les caractères de raies violettes et ultraviolettes du soleil,” in Comptes rendus, 78 (1874), 682–686.
“Photographs of the Spectra of Venus and α Lyrae,” in American Journal of Science and Arts, 3rd ser., 13 (1877), 95, also in Philosophical Magazine, 5th ser., 3 (1877), 238; and Nature, 15 (1877), 218; “Astronomical Observations on the Atmosphere of the Rocky Mountains, Made at Elevations of From 4,500 to 11,000 Feet, in Utah and Wyoming Territories and Colorado,” in American Journal of Science and Arts, 3rd ser., 13 (1877), 89–94; “Discovery of Oxygen in the Sun by Photography and a New Theory of the Solar Spectrum,” ibid., 14 (1877), 89–96, also in Proceedings of the American Philosophical Society (July 1877), 74–80; Memorie della Società degli spettroscopisti italiani, 6 (1877), 69; and Nature, 16 (1877), 364–366; “Observations on the Total Eclipse of the Sun of July 29th, 1878,” in American Journal of Science and Arts, 3rd ser., 16 (1878), 227–230, also in Philosophical Magazine, 5th ser., 6 (1878), 318–320; “Speculum,” in New Universal Cyclopedia (New York, 1878); “On the Coincidence of the Bright Lines of the Oxygen Spectrum with the Bright Lines of the Solar Spectrum,” in American Journal of Science and Arts, 3rd ser., 18 (1879), 263–277, also in Monthly Notices of the Royal Astronomical Society, 39 (1879), 440–447; “On Photographing the Spectra of the Stars and Planets,” in Nature, 21 (1879), 83–85, also in American Journal of Science and Arts, 3rd ser., 18 (1879), 419–425; and Memorie della Società degli spettroscopisti italiani, 8 (1879), 81; “Photographs of the Nebula in Orion,” in American Journal of Science and Arts, 3rd ser., 20 (1880), 433, also in Philosophical Magazine, 5th ser., 10 (1880), 388; and Comptes rendus, 91 (1880), 688–690; “On a Photograph of Jupiter’s Spectrum Showing Evidence of Intrinsic Light From That Planet,” in American Journal of Science and Arts, 3rd ser., 20 (1880), 118–121, also in Monthly Notices of the Royal Astronomical Society, 40 (1880), 433–435; “On Stellar Photography,” in Comptes rendus. 92 (1881). 964–965; “On Photographs of the Spectrum of Comet b 1881,” in American Journal of Science and Arts, 3rd ser., 22 (1881), 134–135, also in Observatory, 5 (1882), 252–253; “On Photographs of the Nebula in Orion and of Its Spectrum,” in Comptes rendus, 92 (1881), 173, also in Monthly Notices of the Royal Astronomical Society, 42 (1882), 367–368; “On Photographs of the Spectrum of the Nebula in Orion,” in American Journal of Science and Arts, 3rd ser., 23 (1882), 339–341, also in Observatory, 5 (1882), 165–167. An extensive collection of Henry Draper’s professional and personal correspondence is on file in the New York Public Library MS collection.
II. Secondary Literature. Principal sources are George F. Barker, “Biographical Memoir of Henry Draper 1837–1882,” read before the National Academy (Apr. 1888); and “Researches Upon the Photography of Planetary and Stellar Spectra by the Late Henry Draper, M.D., LL.D., with an introduction by Professor C. A. Young, a List of the Photographic Plates in Mrs. Draper’s Possession, and the Results of the Measurement of these Plates by Professor E. C. Pickering,” in Proceedings of the American Academy of Arts and Sciences, 19 (1884), 231–261. Other sources are “‘Minute’ on Henry Draper,” in Proceedings of the American Philosophical Society (Dec. 1882); T. W. Webb, “Draper’s Telescope,” in Smithsonian Annual Report (1864), pp. 62–66, repr. from Intellectual Observer (London); and George F. Barker, “On the Use of Carbon Disulphide in Prisms; Being an Account of Experiments Made by the Late Dr. Henry Draper of New York,” in American Journal of Science, 3rd ser., 29 (1885), 1–10.
Charles A. Whitney
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