Dorrit Hoffleit

Memoirs of the Connecticut Academy of Arts and Sciences, Volume XXIII

Printed with the permission of the Connecticut Academy of Arts and Sciences.

OVERVIEW OF TWO AND A HALF CENTURIES

The following letter was written by Frank Schlesinger, Director of the Yale Observatory from 1920 to 1941, to Burton E. Livingston, then President of the American Association for the Advancement of Science, dated Sept. 20, 1920. It concerned a proposal to establish a History of Science Section in the AAAS.

At the request of Dr. Brasch [F. E. Brasch of the Library of Congress] I give you herewith a brief word in statement of my opinion regarding the importance of the study of the history of science. I have always been of the opinion that in this country we have neglected too much this side of science. As in other fields of human endeavor, the history of the subject has a most important function in teaching us what mistakes to avoid, and what is the best attitude to maintain regarding new ideas and new theories. The study of biographical works is, in my opinion, especially important for the young scientist. It tells him better than anything else can what rewards he can hope for and what discouragements and obstacles he must expect to encounter. I have no doubt that a great many bitter disappointments might be averted if such information as this could be put into the hands of beginners as early as possible. (1)

When New Haven Colony was founded in 1638 its leader, Rev. John Davenport, strongly advocated establishing a college there similar to Harvard. After innumerable obstacles, Yale College was finally founded in 1701, the third college in the colonies after Harvard and William and Mary. Typically of the times, its major goal was the training of young men for the ministry, in this case exclusively the Puritan or Congregational. One of the earliest topics taught, aside from theology, was astronomy with, however, pointed allusions to its exemplification of the power and bounty of God. With the acquisition in 1714 of scientific books from England, especially Isaac Newton's Principia and Opticks, the tutors began learning his new branch of mathematics, "fluxions," now known as the calculus. This knowledge was essential to the understanding of both gravitation and the principles of optics.

The apparition of a spectacular fireball in 1742 gave rise to President Clap's amazing theory of Terrestrial Comets . The impending expected return of the comet, later named Halley, further stimulated the early study of celestial mechanics, mainly for the determination of orbits. The great shower of meteorites at Weston, Connecticut, in 1807 prompted investigation on its extraterrestrial origin, established by B. Silliman and J. Kingsley at Yale. Comets and meteors and their concomitant application of celestial mechanics appear to have been the major objects of research for nearly two centuries.

With the acquisition of the 5-inch Dollond telescope in 1829, the gift of Sheldon Clark, Yale achieved the enviable distinction of having the largest refractor in America. This reputation was enhanced when Professor Dennison Olmsted and Tutor Elias Loomis in 1835, using the telescope, were the first in America to spot Halley's comet upon its expected return that year. In 1833 the magnificent Leonid meteor shower was observed by Olmsted, and at West Point by A. C. Twining, resulting in the first acceptable cosmical theory of the origin of meteor showers. Later, H. A. Newton, comparing the observations of 1833 with much earlier displays, was the first correctly to predict the return of the Leonids in 1866, and showed how perturbations by Jupiter had changed the original course of the swarm.

Unfortunately, Yale's eminence dwindled as Harvard in 1847 acquired its famous 15-inch "great refractor" and the Yale administration slackened its interest in astronomy. Although William Hillhouse in 1856 bequeathed instruments (especially a transit instrument), and in 1858 Mrs. James A Hillhouse and her daughters gave six acres of choice land in memory of her father-in-law, James Hillhouse, Yale Treasurer 1782 - 1832, especially for the erection of an observatory, nothing came of these gestures and the able astronomers struggled along as best they could without adequate support, nevertheless achieving noteworthy results based on such observations as their meager equipment allowed. In 1871 Oliver Winchester gave 32 acres of land for the erection of an observatory, most of the land to be sold to provide funding for the proposed buildings. The national financial crisis of 1873 frustrated his plans. On a scale much reduced from the original architect's drawings, the observatory on the corner of Prospect and Canner Streets was finally erected in 1882. Largely to meet operating expenses, the horological and thermometric bureaus were set up by Leonard Waldo. Very successful at first, they, too, were discontinued.

Meanwhile, new and exciting projects were undertaken. The observatory (for a time known as the Winchester Observatory) under the direction of H. A. Newton, ordered a heliometer, a divided objective telescope such as F. W. Bessel in Königsberg, Germany, had used for the determination of the first reliable published parallax of a star, 61 Cygni, in 1838. The Yale heliometer was the first and only such telescope in America and at that time the largest in the world, with a diameter of 6 inches. The first scientific use made of the new instrument was for the observation of the transit of Venus in 1882. In 1884 W. Lewis Elkin was appointed astronomer in charge of the heliometer. He had spent the previous two years in South Africa working with David Gill at Capetown and learning the techniques of that most experienced expert on the determination of stellar parallaxes with the heliometer. At Yale, Elkin is reputed to have determined more and better parallaxes than anyone before the advent of photography made the visual technique obsolete. Elkin himself was well aware of the potential advances in astro-photography, having analyzed Gould's reductions of Rutherfurd's famous pioneering plates of the Pleiades, and measured some Lick photographs.

At the same time, Elkin made significant strides in the study of meteors. Acting upon a suggestion made much earlier by J. Homer Lane, Elkin built two batteries of cameras equipped with rotating shutters for obtaining the velocities as well as the heights of meteors. His pioneering efforts provided the model for more precise programs instituted at Harvard decades later.

Thus, by the beginning of the twentieth century comets and meteors, celestial mechanics applied chiefly to orbital calculations, and finally astrometry were the main subjects of interest at Yale. After Elkin's retirement in 1910 until the appointment of Schlesinger in 1920, the observatory was inactive. In this interval E. W. Brown perfected his lunar theory and worked on his massive lunar tables. No further work of note on meteors has been carried out at the Yale observatory except for a paper on meteoritic dust by R. Wildt and an undergraduate, P. Hodge, in 1956. After more than a century of pre-eminence in studies of meteors, this field became effectively non-existent at Yale.

Schlesinger brought new light and new subjects. He has been described as "the father of modern astrometry." It was mainly he who perfected the photographic methods for parallax determination, and who initiated the programs for "zone catalogues" - the determination of precise positions of tens of thousands of stars in discrete belts around the sky, and their proper motions obtained by intercomparing positions measured at large time intervals, usually on the order of 20 years. With the collaboration of Jan Schilt, first at Yale, later at Columbia, the magnitudes for a high percentage of the stars in the zone catalogues were determined.

While Schlesinger concentrated his own research efforts on astrometric problems, he did not fail to encourage others in different aspects of astronomy. Notably, during his regime, graduate student John Hall was the first to do pioneering work on infra-red photometry of variable stars, inventing his own equipment. Following him, Dr. Arthur Bennett improved the equipment and carried out many more observations.

In 1925 Schlesinger established a Southern Station at Johannesburg, South Africa, where he erected a 26-inch Grubb long-focus refractor for the determination of parallaxes of southern stars. This telescope was in operation at Johannesburg until 1952 where 66456 plates had been taken. It was then moved to Mt. Stromlo where the total number of plates was increased to 69950. In 1963 Yale left Mount Stromlo and donated the 26-inch to the Australian observatory. Also as early as 1928 a "catalogue camera" was erected at Johannesburg for extending the zone catalogue work far into the southern hemisphere. Clearly, astrometry reigned supreme during Schlesinger's directorship.

Meanwhile E. W. Brown and Dirk Brouwer were deeply immersed in the problems of theoretical mechanics. When Brouwer took over the directorship in 1941, celestial mechanics was soon to catapult to world wide pre-eminence at Yale. This tremendous achievement was, of course, given most significant impetus by the advent of the "space age." Celestial mechanics is vital to the navigation of space vehicles. Astrometry, however, was not neglected. While the work on the parallaxes continued, it did so at a reduced pace. The zone catalogue work, on the other hand, was pushed, although not for the sake of studying the stars as such, as Schlesinger did, but because Brouwer considered the astrometry of the zone catalogues as "the handmaiden of celestial mechanics." The positions and a knowledge of their changes of position, provided an essential reference frame for the determination of precise positions of solar system objects, particularly for the asteroids, and of space vehicles. Stellar astronomers, on the other hand, still viewed the zone catalogue data as most essential to the analysis of galactic structure, galactic rotation, and the assignment of stars to the various population groups.

For a relatively short time Yale indulged in a radio-astronomy program especially concerned with radiations from the planet Jupiter. Although preliminary results were encouraging, the University policy of "publish or perish" was detrimental to the projects of long duration, especially the innovative ones. No matter how worthwhile, they do not yield definitive results quickly, so the investigators had to leave. They took their equipment with them to Texas.

During Brouwer's regime, photometry (especially of variable stars) and astrophysics (under R. Wildt) were by no means neglected, although they played a comparatively minor role. After Brouwer's death in 1966 Wildt, as Acting Director, discouraged the continuance of most of the theretofore predominant projects. When Dr. Pierre Demarque came as Director in 1968 the remaining active projects were again encouraged; but now theoretical astrophysics, studies of external galaxies, and cosmology became the major topics of investigation.

Throughout the time span of this survey, a change in directorship generally brought about a change in emphasis to different sub-branches of astronomy. In each era, however, Yale proved itself a leader, at least in America, in whatever field it specialized at the time.

Reference

1. F. Schlesinger to B. E. Livingston, Sept. 20, 1920, Yale Obs. Archives.

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