figuration of nebulæ, even more wonderful are the recent stellar discoveries made by photographing the spectra of the stars. It is in this last-named branch of astrophysics, that the women assistants at the Harvard Observatory have accomplished important results.

far achieved by

these women assistants are Mrs. Fleming's discovery that variable stars of a certain type may be proved variable by the bright lines in their spectra, and Miss Maury's discovery that Beta Aurigae is a close binary, proved so from the study of its spectrum. Yet the whole experiment of employing women to the extent to which they are here employed is worthy

necessary appliances; while ranged in the hallway and antechamber are numerous wooden boxes containing the brittle though perishable glass plates, those indisputable records of the Draper Memorial work. In these very glass plates is seen one of the chief advantages derived from the application of photography to astronomy. For these plates reproduce the condition of the same region of the sky at various periods, and hence may be referred to at any time to confirm any discovery. Should a bright star suddenly appear in the sky, its previous absence or comparative faintness could at once be proved from these incontrovertible records.

of attention. For the Harvard Observatory is the first to develop a corps of trained women assistants, dealing with difficult problems as successfully as men deal with them at other observatories; and this corps of women, in addition to doing thorough routine work, has shown great capacity for original investigations. Moreover, they are employed not from the meaner motive which so often leads to the opening of some new field for women's work, viz., that their work can be obtained at a cheaper rate than that of men; for the women assistants doing routine work are paid at the same fixed rate per hour as the men in other departments of the Observatory who do the same kind of work. Work paid for by the hour possesses certain obvious advantages, since the worker is thus tied down to no fixed hours, and she may even do portions of her work at home. Much of the Harvard Observatory work is, however, carried on in two light, pleasant rooms, of which illustrations are here shown. These rooms

The work in which women take part at the Harvard Observatory may be divided into three classes.

1. Computing, based on the work of others. For twenty years some women have always been included in the corps of Harvard computers.

2. Original deductions (not necessarily star-work). Work of this kind has been carried on chiefly by special students of the Harvard Annex. In this class of work must be named a longitude campaign-probably the only longitude campaign ever conducted wholly by women, whereby Miss Byrd and Miss Whitney determined the precise difference in longitude between the Smith College and

Harvard College Observatories. Miss Bryd is now director of the Smith College Observatory, and Miss Whitney is Maria Mitchell's successor at Vassar. In this second class of work may be included also the making of a standard catalogue of the stars near the North Pole by Miss Anna Winlock, the daughter of a former director of the Harvard Observatory.

3. The Henry Draper Memorial work, and four other investigations, less extensive, though similar in kind to those provided for by the Draper fund.

As the Draper Memorial investigations form one of the most noteworthy departments of the Harvard Observatory, and as these investigations under the general direction of Prof. E. C. Pickering, the director of the Observatoryare carried on by women, the present article will devote itself principally to a description of this work. Moreover, the work is supported wholly by a woman, Mrs. Anna Palmer Draper of New York, in honor of her husband, Dr. Henry Draper, who was a pioneer in the work of photographing stellar spectra.

Henry Draper, son of the distinguished

Draper Photographic Telescope.

John William Draper, was born in Virginia, March 7, 1837. He received the degree of Doctor of Medicine from the University of the City of New York in 1858, and for eighteen months after his graduation was on the staff of the Bellevue Hospital. At the end of this time, he was chosen professor of Natural Science in the Academic Department of the

had already begun to tell on him, and he died Nov. 20, 1882, after a brief illness. As an instructor, Henry Draper received the highest praise from his students; for he possessed to an unusual degree the power of kindling their enthusiasm while adding to their store of knowledge. Yet, engrossing as were the duties of Dr. Draper's chosen vocation, he still found time for an avocation that would have sufficed for the life-work of most men. Furthermore, on the death of his father-in-law, Mr. Cortland Palmer, in 1871, he became managing trustee of a large estate, and in this position was known as an exceedingly efficient business man. Finally, he by no means neglected society, but had a large circle of warm friends, among whom he was distinguished for his wit and conversational powers. was fond of art, music, and outdoor sports; and he spared neither the great wealth at his command nor his own energy to pursue to a successful end those scientific investigations in which he was interested.

He

The avocation referred to above was spectroscopic photography. In this branch of practical astronomy, Dr. Draper was an indefatigable worker. His fame as a scientific man is based on his photographic investigations, as regards,

1. Diffraction spectrum of the sun.

2. Stellar spectra.

thesis; and his interest in astronomy received an impetus when, in 1857, during a European tour, he had an opportunity to see the great Rosse telescope. On his return to America, he began to construct for his own use, a telescope similar to the Rosse telescope, though much smaller. So striking were the experiments successfully carried on by the young man while constructing this fifteen and one-half inch reflecting telescope, that they attracted

3. The existence of oxygen in the sun. 4. Spectra of the elements.

Undoubtedly, the fact that from earliest youth Henry Draper had been his father's assistant and confidant in many of the experiments undertaken by the latter did much to develop his scientific ability and acumen. His interest in photography was aroused during his medical course, when he had had occasion to make a series of micrographs, illustrating certain microscopic studies, for his graduation

the attention of Prof. Joseph Henry. The latter, visiting Dr. Draper's observatory in 1863. induced him to write a monograph "On the Construction of a Silvered Glass Telescope fifteen and onehalf inches in aperture, and its use in Celestial Photography," which appeared in July, 1864, as No. 180 of the Smithsonian Contributions to Knowledge.

To his observatory at Hastings on the Hudson, Dr. Draper soon added a photographic laboratory, and for several years devoted himself to celestial photography.

It was not until after the completion of his great twenty-eight-inch telescope, in 1872, that Dr. Draper secured his first successful photograph of the spectrum of a fixed star. This photograph, obtained without slit or lens, by using a quartz prism placed just inside the focus of the smaller mirror, was the result of a long investigation carried on by him for several years. He made gradual improvements in his methods, and was greatly aided in his work by the invention of dry plates in 1879. In October, 1879, he read a paper before the National Academy of Sciences, which attracted much attention, and from August, 1879, until his death, he made seventy-eight photographs of stellar and planetary spectra.

Although in the photographing of stellar spectra may be counted Dr. Draper's most valuable contributions to science, other branches of astronomy deeply in

terested him. In 1874, he was appointed Director of the Photographic Department of the United States Commission established to observe the transit of Venus. Devoting himself to this work for three months, in spite of the fact that his home duties prevented his actually joining the expedition, the success of the observations was so largely due to him, that Congress ordered a special gold medal struck in his honor at the Philadelphia Mint.

Dr. Draper also organized and directed a small expedition to view the total solar eclipse of July 29, 1878. The party was a notable one, consisting of Dr. and Mrs. Draper, Mr. Thomas A. Edison, Prof. Henry Morton, and Mr. Geo. F. Barker. The station, Rawlins, Wyoming, had been selected' by Dr. Draper on account of its favorable atmospheric qualities; and the expedition was so well equipped, that Dr. Draper was able to reach the conclu