The Brooklyn Daily Eagle from Brooklyn, New York • Page 97

1 Past Seven ounted the Otars in tlie. JTlLeavens i i Annie Jump Cannon Has Compiled Census of the Astral Hosts at Harvard University on Basis of Spectrum Identification i I -tts By Helen Fitzgerald A CATALOGUE of nearly a quarter of a minion stars, or, to "be exact, 225,300, covering the sky from the North to the-South Pole, is the tremendous tasfc achieved "bya woman, Annie Jiynp Cannon, Curator of Astronomical of Harvard College Observatory. In addition to she discovered three hundred variable stars, a great number if we recall that In the middle of -the Nineteenth Century only eighteen were known, and she has added four to the Est of novae, or new stars. Because of Tier contribution to astronomy, Miss Cannon has received three outstanding honors; a doctorate of science from the University of Groningen, Holland, famous for its department of astronomy; the honorary degree of doctor of science from Oxford University, bestowed for fhe first time' upon a woman, and, finally, when the League of Women Voters named the twleve greatest Eying women in the United States, she was chosen in her own fields-science. To approach a person who is absorbed in cosmic rather than little mundane matters fills' the layman with qnalms of awe.

But Miss Cannon's voice was reassuringly pleasant over the telephone when I asked for an appointment and there were no vexatious delays-She would be at at two o'clock in the afternoon.lt was then eleven. I offered up a little prayer of thankfulness for the simplicity and directness of the great After the first iurried greeting she vanished, explaining that she wished to have me meet Dr. Harlow Shapley, Director of the Observatory. Dr. Shapley gave me some interesting facts concerning the Observatory and Miss Cannon.

Next to her major interest which is, of course, the variability of the stars, and the classification of stars according to their spectra, she is most concerned in helping young women who are taking up astronomy as a life work. Under her are a number of women assistants engaged in checking and recording observations made from photographs. Harvard Observatory gives opportunities to women equaled in no other institution of learning in the world. Professor Edward C. Pickering, who was its director in the nineties, organized the first corps of women assisfants in any observatory, believing in their peculiar ability.

Miss Cannon began her work there under him and has remained ever since, over a period of twenty-five years. Dr. Shapley is no less firm in his faith in the ability of women in this branch of science, and to back him up he has the living example of Miss Cannon. He hopes that some day, as a tribute to her work, there may be a fund to support the searchers of brilliant young women astronomers. This pleasant introductory talk over, Miss Cannon returned.

In spite of the intense summer heat, she had a cool appearance in her white silk gown with a fine pattern of black. Her clear, blue eyes had a starry light, as though the rays upon which she gazes were reflected in them. "I deserve no particular credit," she said. "I have concentrated on my work that is all. I find it so fascinating and absorbing that nothing else exists.

The trouble with most women is they do not stick to their work. They marry and drop it Mind," she added, "I believe marriage is a fine thing, if a woman marries the right man. But it should not stop a woman's work any more than it does a man's. "It might seem that examining an hourly average of 200 streaks with vertical lines through them would not be particularly interesting. I know if my whole heart were not in it, such a task would be monstrous.

But they aren't just streaks to me every new spectrum is the gateway to a wonderful new world." In reply to my question as to how she first became interested she said: "Through my mother, who studied astronomy in Quaker finishing school near Philadelphia. The subject fascinated her and her enthusiasm inspired me. The women of the past generation were better informed in elementary astronomy than those of today. Of course that does not apply to college girls who are specializing in astronomy and other branches of science. "My mother taufcht me the constellations when I was a young child.

Our home was in Dover, Delaware, where I was born. The old house was so sheltered by trees that it was impossible to study the stars from the windows and porches, but from the attic I made observations. There I went regularly after dark, opened a trap door and, with an old book on astronomy containing charts, by the light of a candle, I learned to identify the stars." The result of those evening vigils determined her future career. In 1884 she received her B. S.

degree from 'Welles-ley College. The most spectacular episode of her college days was the appearance of the Great Comet of 1882. Evidently she feels kindly toward comets as celestial publicity agents, for she said: "I wish we could have another great comrt It would stimulate interest in astronomy." Later she returned to Wellesley for graduate study Annie Jump Cannon to tell of their constitution and physical condition. "By a careful study of the intensities of the lines hi the spectrum of star light, split up by an objective prism as I have described, the stars have been arranged in orderly groups, according to the metals most In evidence. This involves comparison with the spectra of earthly substances." It la said by an authority that "such a grouping has proved to give the key to the evolutionary development of the stars." Miss Cannon showed me a number of plates, pointing out the lines indicating calcium, magnesium, bydrogea and helium.

An extraordinary fact is that certain substances hitherto unknown on our earth have been first discovered through stellar spectra and later identified on this planet. Miss Cannon said: "Take, for example, helium. In 1801 Professor Pickering wrote: 'The principal question now outstanding is to determine what substance or substances ciuse tho characteristic lines in the spectra of stars of the Orioa type This question was settled by Sir William Ramsay 'a discovery of helium in 1895, and the subsequent identification by Vogel of the lines characteristic of spectra of the Orion type with the new terrestrial clement Heocs the so-called Orion stars, which were first known to prevail in that constellation, became helium stars." Miss Cannon then showed me two more plates. On one of these a single line and on the other a double lins was visible. These were photographs of a spectroscopic binary.

Miss Cannon explained: "All of these binaries consist of two stars nearly equal in brightness, revolving around common center of mass, with rapid velocity, in periods of from one to twenty days. Tlwre are now more than 1,000 spectroscopic binaries known, but in most of them one component is so much fainter that Its lines are not visibli on the photographs and its presence Is revealed only by the variable velocity of the system in the line of sight." Miss Cannon with almost superhuman vision and Intuition classifies the stars on the plates, and ber obter-Virions are noted and checked by the young women assistants, on Library Bureau cards, which are placed in filing cases in the order of right ascension, where they can be readily consulted. Thus the actual work Is don from photographic plates rather than direct observation of the stars. These photographs are kept In the main station of tho Observatory at Cambridge. They are stored in fireproof compartments in the stack room.

Each compartment contains 100 original glass negatives 8x10 inches in site. The "collection resembles a library of books, "of which each negative is the only existing copy, and, being glass, is very fragile." It is unique in the scientific world and contains 300,000 plates, "the history of the sky for thirty, five years." Miss Cannon went to Arequipa, Peru, where the Observatory maintained a station, to study the southern staia. During her stay there she discovered ber fourth nova, studied its spectrum and photographed stars of Hie southern constellations. in mathematics, physics and astronomy. At this time she became Interested In the subject of the spectroscopic analysis of light, under the direction of Prof.

Sarah F. Whiting, who established the physical and astronomical departments of Wellesley College. Later she entered Rad-ciiffe College, Cambridge, for more advanced work. She then went to the Harvard Observatory to work under Prof. Edward Pickering, beginning her study of variable stars and the classification of stars by means of spectra registered on photographic plates.

Speaking of her peculiar ability, Professor Pickering once said: "Miss Cannon is the only-person in the world man or woman who can do this work so quickly." To illustrate her extraordinary speed, 5,000 of more stars were classified by; her each month during the making of the Henry Draper Memorial Catalogue. This seems an incredible number when one considers that "although people think they can seormillioos of stars on a clear night, as a matter of fact the average human eyo can discern only about 2,000." This unique faculty of MJ as Cannon was exemplified in her first published work, "Classification of 1,122 Bright Southern Stars," which appears In the Annals of the Observatory. This proved to-be the stimulus which resulted in the marvelous achievement, the Henry Draper Memorial Catalogue, which contains the class of spectra of 225,300 stars. At the time this tremendous work was begun. In 191 1, Miss Cannon became Curator of Astronomical Photographs, succeeding Mrs.

W. P. Fleming, who Is said to be the first woman who ever bad her name In a Harvard catalogue. The Draper catalogue was made possible by the Henry Draper Memorial, a fund given by Mrs. Henry Draper in memory of her husband, a professor of chemistry at the College of the City of New York, wbo was the first to photograph successfully the spectrum of a star.

There have been other gifts to supplement this fund. To the layman stellar photography and classification according to spectra seem magic. The analysis of stellar spectra is literally the key to the stuff that stars are made of I To elucidate the process. Miss Cannon led the way into a room with large windows where several bright-looking young women were examining photographic plates. She picked up a plate and asked me to hold it up to the light It was covered with streaks showing fine lines of varying density.

Speaking of early stellar photography Miss Cannon said: "While the general survey of the whole sky was made with the 8-incb telescopes, excellent spectra of the brighter stars were obtained with Dr. Draper's 11 -inch photographic lens, having a focal length of 153 inches, which had been remounted in Cambridge. The brighter stars thus be photographed, by means of four prisms nearly a toot square, placed before the object glass. "The prism breaks up the rays and gives the spectrum of each starv "The revelations of these photographs of stellar spectra are truly remarkable. It is almost as if the distant stars had really acquired speech and were able.