Chicago Astronomical Society
Chicago Astronomical Society Soundex Code S230
Founded in 1862, the Chicago Astronomical Society works to promote information about the study of stars, planets, and other celestial bodies.
The Dearborn Observatory was founded by citizens of Chicago by volunteer contributions. These men had confidence in the commercial future of their city, and strove to keep her standing in learning abreast of her commercial progress. The foundation of the Dearborn Observatory and the erection there of a great telescope was one expression of their desire that their city should contribute her share to the results of scientific research.
The movement formally started in 1862, when the Reverend M.R. Forey came to Chicago to effect the sale of a 16-inch Fitz refractor and incidentally delivered a lecture, "The Sideral Heavens", on Monday, December 8, 1862. A committee composed of prominent Chicago citizens was appointed after the lecture to carry out the plan of building an observatory in Chicago. The Chicago Astronomical Society was organized permanently in 1865 and incorporated in 1867. But as a group of responsible men earnestly concerned with the intellectual progress of their city, it really existed even before the date of Reverend Forey's lecture.
After the decision of Monday, December 8,1862, further progress followed promptly. Because there was some doubt as to the reliability of the Fitz refractor, a representative was dispatched to Ann Arbor, Michigan for consultation. It was there learned of the availability of an 18 1/2-inch lens in the shop of it's maker, Alvan Clark & Sons, of Cambridgeport, Massachusetts. This lens had originally been ordered by the University of Mississippi, but the outbreak of the American Civil War prevented the transaction from being completed. Under highly dramatic circumstances, the Chicago society purchased the 18 1/2-inch lens on Saturday, January 10, 1863, for $11,187.00.
Three weeks later, on the evening of Saturday, January 31, 1863, while testing the new lens at their Cambridgeport shops, the Clarks made the chance discovery of the faint companion to the star Sirius. In 1844 the great Friedrich Bessel at Königsberg, Germany, had predicted from variable proper motion of Sirius that it must have another disturbing body of considerable mass revolving with it. (In recent years the evidence has been accumulating that this faint star has the astonishing mean density of around 50,000 times the density of water. A piece of this material as large as an ordinary safety match box would weigh one and 2/3 tons!) One can easily imagine the thrill which the members of the Society in Chicago must have felt when news of this discovery reached them. Their lens had already distinguished itself above all other lenses then in use.
Later in 1863, the Society placed the 18 1/2-inch lens and it's mounting (also made by the Clarks, at a cost of $7,000) in the charge of the University of Chicago (1857-1886). One of the leading spirits in the Society, Mr. J.Y. Scammon donated the money for a suitable tower and dome to house the telescope.
Mr. Walter Smith Gurnee, the 14th Mayor of Chicago, donated $5,000 for a first class meridian circle for the new observatory. The final cost of getting this instrument, (by Repsold & Sons, of Hamburg, Germany), delivered in Chicago was $7,416.
On Thursday, December 28, 1865 the Society appointed Mr. Truman H. Safford as the first Director of the Dearborn Observatory & Professor of Astronomy in the University of Chicago. In the next five years he entered upon several major programs of observation, and carried them forward with vigor until the Great Chicago Fire on Monday, October 9, 1871. Up to this time Mr. Scammon had paid the salary of Professor Safford. He was now no longer able to carry this financial burden, and Professor Safford, on leave of absence, joined the U.S. National Geodetic Survey. A number of these investigations were published in the appropriate journals or reported to the Society. Others, such as his meridian circle observations of a zone of the sky, were interrupted and never finished.
Mr. Elias Colbert and Mr. Sherburne Wesley Burnham by turns carried over the supervision of the Dearborn Observatory from 1871 until Tuesday, May 6, 1879, when Professor George Washington Hough was appointed Director and began his observations, although neither the Society nor the University of Chicago was able to pay him a suitable & regular salary until 1881.
In 1887 the affairs of the University of Chicago reached a crisis which indicated to the Directors of the Society that other arrangements would have to be made to insure the continuance of the Dearborn Observatory.
A contract was thus entered into by the Chicago Astronomical Society and Northwestern University on Saturday, October 29, 1887, for the reestablishing of the Dearborn Observatory on the campus in Evanston. The new Dearborn Observatory, a charming gray stone building familiar to many people in the Chicago area, was the gift of Mr. James B. Hobbs of Chicago, an officer of the Society and a trustee of Northwestern University from 1883 until his death in 1914.
Professor Hough (Director from 1879 to 1909) devoted himself to the discovery of close double stars, physical observations of the planets & their satellites, observations of comets, investigations of instruments, and maintenance of time services. (As early as 1875, the Dearborn Observatory was supplying time to the Chicago Board of Trade, the Elgin National Watch Company, and others.) Professor Hough's numerous papers were published in various astronomical journals in America and abroad.
He was followed on Wednesday, September 1, 1909 by Professor Philip Fox, who directed the Dearborn Observatory until June of 1929, when he resigned to become organizer and Director of the Adler Planetarium, in Grant Park, Chicago.
During these years, Professor Fox made many thousands of observations of double stars, some of which he discovered, and published them in Volumes I & II of the Annals of Dearborn Observatory. He was enabled to complete the observations on the rotation of the Sun which he had begun while at the Yerkes Observatory, and to publish them. In 1912 he began taking photographic plates with the 18 1/2-inch refractor for the determination of stellar parallaxes. (Abstracts of parallax results were published in appropriate journals from time to time, and full details in the conventional form adopted by parallax observers, were published in 1935 as Volume III of the Annals.)
Quite soon after Professor Fox began his directorship at Dearborn Observatory, he designed and built a stellar spectrograph. Due to the interruption of World War I, and the pressure of other programs of research, observations with this instrument were not begun until August, 1920. By the time regular work with this spectrograph was discontinued,(Thursday, March 20, 1930) a library of over 1,800 spectrograms of excellent quality, mostly of bright stars, had been accumulated. Several papers & notes have been published for which this material was used.
In 1913, Northwestern University provided an updated mounting & driving gear by the firm of Warner & Swasey. It replaced the aging Clark mounting of the 18 1/2-inch lens, which had never been designed to meet the demands being placed upon it by newer techniques and instrumentation. The original is now on display at Adler Planetarium, Chicago. During Professor Fox's energetic directorship, most of the instruments and other physical equipment of the Dearborn Observatory were modernized, and the library was organized and greatly enlarged by completing files of scientific journals, and by adding all the important observatories to the exchange list for publications.
