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 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 Dec.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 & 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 Dec.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, Mass. This lens had originally been ordered by the University of Mississippi, but the outbreak of the Civil War prevented the transaction from being completed. Under highly dramatic circumstances, the Chicago society purchased the 18 1/2-inch lens on Jan.10, 1863, for $11,187.00.

Three weeks later, on the evening of Jan.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 Bessel at Konigsberg, 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 $7000) in the charge of the old 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 S. Gurnee, a former 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), delivered in Chicago was $7,416.

On Dec.28, 1865 the Society appointed Mr. Truman H. Safford as the first Director of the Dearborn Observatory & Professor of Astronomy in the University. In the next five years he entered upon several major programs of observation, and carried them forward with vigor until the Chicago Fire on Oct.9, 1871. Up to this time Mr. Scammon had paid the salary of Prof. Safford. He was now no longer able to carry this financial burden, and Prof. Safford, on leave of absence, joined the United States Coast-& 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 Observatory from 1871 until May 6, 1879, when Prof. George Washington Hough was appointed Director and began his observations, although neither the Society nor the Univ. of Chicago was able to pay him a suitable & regular salary until 1881.

In 1887 the affairs of the University 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 Observatory.

A contract was thus entered into by the Chicago Astronomical Society and Northwestern University on Oct.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 Observatory was supplying time to the Chicago Board of Trade, the Elgin Watch Co.,& others.) Prof. Hough's numerous papers were published in various astronomical journals in America and abroad.

He was followed on Sept. 1, 1909 by Professor Philip Fox, who directed the Observatory until June of 1929, when he resigned to become organizer and Director of the Adler Planetarium & Astronomical Museum, in Grant Park, Chicago.

During these years, Prof. 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 Prof. Fox began his directorship at Dearborn, 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,(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 tile 18 1/2-inch, which had never been designed to meet the demands being placed upon it by newer techniques & 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 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.

After the Market Crash of 1929, the Society found itself unable to properly fund, maintain, or operate the Observatory. Therefore, reluctantly, on April 30, 1930, the Chicago Astronomical Society formally relinquished to Northwestern University its title to the 18 1/2-inch lens, the meridian circle, and many other items of equipment in the Observatory, with the provisos that the instrument be maintained, and that the Observatory be open to the public for observations, without cost, throughout the year. Over the years countless persons availed themselves of this opportunity to observe the moon, planets, nebulae, stars & star clusters with the 18 1/2-inch telescope, and to hear short explanatory lectures about the objects they see.

The University accepted this magnificent gift into which had been poured so much enthusiasm and constructive effort over the years. This action closed, in a most amicable fashion, a chapter in an association which had persisted for nearly forty-three years.

Needless to say, the activities of the Society went into a decline for a number of years after this time. However, in mid-1955 the Chicago Astronomical Society merged with the very active Burnham Astronomical Society, also of Chicago, which had been founded in 1941 as the successor to the Chicago Telescope Makers.

It was this marriage of prestige & vitality which has resulted in the Society as we know it today.


(The following is a text of the document of incorporation of the Chicago Astronomical Society)

Originated in the House of Representatives

L.G. Riddock, Clerk

An Act To Incorporate the Chicago Astronomical Society


Whereas, An association has been formed in the city of Chicago called "the Chicago Astronomical Society", the object of which is to support an observatory, and diffuse astronomical knowledge; now, in order to encourage the objects of said association:

Section 1, Be it inacted by the people of the state of Illinois, represented in the General Assembly, that J. Young Scammon, Thomas Hoyne, William B. Ogden, W.H. Wells, James H. Woodworth, D.J. Ely, J.K. Pollard, Louis C. Jones, Ezra B. McCazy, John C. Burroughs, A.H. Mixer, Thomas B. Bryan and their associates and successors forever, are hereby created a body politic and corporate by the name of "the Chicago Astronomical Society" and by that name shall have perpetual succession, shall be capable in law to sue and be sued, plead and be impleaded, within all courts of competent jurisdiction; may receive, acquire and hold real and personal property and effects, and dispose of the same at pleasure; may make such constitutions, regulations and by-laws, as may be requisite for its government, and for carrying out the objects of the society, and may alter the same at their pleasure.

Section 2. The constitution and by-laws of said society now in operation shall govern the corporation hereby created, until altered or repealed by the association, and the present officers of the executive or observatory board shall be the officers of said association, and their term of office, powers and duties shall continue the same as now prescribed, appointed by the constitution until otherwise regulated or changed by the directors of said observatory.

Section 3. All the money's, property and effects of said society except the land of the University of Illinois upon which the observatory tower is erected, shall be held and managed by the directors of said society, and the management of all the affairs of said society, the management of and observations of the observatory, the employment of a professor or professors, of astronomy, and their assistants; the raising of funds and disbursements thereof and the support and maintenance of said observatory shall be vested in the directors of said observatory, who shall constitute from their own number an executive or observatory board of said directors, and the members of said observatory board shall hold their offices according to the tenure prescribed by the constitution and by-laws of said society, and the said executive board shall appoint the president, vice-president, secretary and treasurer of said board, who shall also act as the officers of said society; and the said board shall transact, regulate and manage all matters pertaining to the said observatory, keep a full and complete record thereof, and make safe a proper investments of all moneys and funds outscribed or entrusted to their care so as to permanently support and endow the observatory. This society being an institution formed and maintained solely for the advantage of the public, it and its property and estate of every name and description, are hereby declared to be exempt from all taxation under the authority of this state.

Section 4. This act shall be a public act, and shall be in force from and after its passage.

Speaker of the House of Representatives

Speaker of the Senate

Approved February 19, 1867

Volume 2, Page 258 164

KBN 490 No 128

An Act to Incorporate the Chicago Astronomical Society

No 9935 Box 236

Enrolled Feb. 15, 1867