Sayre Observatory was erected in 1868 with Robert H. Sayre's generous $5000 gift to Lehigh University for the building and equipment. The land where the Observatory stands was originally seven acres and was granted to the university by Charles Brodhead, Esq. of Bethlehem.
Professor Charles L. Doolittle made a large series of latitude determinations with the Sayre Observatory's zenith telescope. This data helped confirm the important claim made by Dr. Küstner of Berlin around 1885 that the earth's poles varied in position. According to the Alumni Bulletin of Lehigh University (vol. 11, no. 4, January 1924), "Dr. S. C. Chandler, an author on theoretical astronomy and Editor of 'The Astronomical Journal,' of Boston, in the issue of August 23, 1892 says: 'Professor Doolittle must be regarded as a pioneer in this subject, having devoted himself to it years before the reality of latitude-variation was generally regarded as possible. The accuracy, homogeneity and continuity of his observations make the series the most valuable of any we possess.'" Doolittle's observations enabled a more accurate determination of the "constant of aberration". From the new value of the constant, it followed that the sun is almost 300,000 miles greater than had been previously thought.
In the late 1920's, the city of Bethlehem brought a trolley line to Brodhead Avenue. The resulting vibrations made precise observations impossible with the delicate telescope. After this, Sayre Observatory was used only for lectures, graduate student thesis research, and amateur observations with the telescope. Astronomical use of the observatory ceased in the 1950's, and the telescope was removed in 1961.
Today, Sayre Observatory houses the Graduate Student Council.
Sayre Observatory ca. 1942
According to the Lehigh Register for the 1904-1905 academic year [Sayre Annex] "contains a modern zenith telescope of four inches clear aperture equipped with electric illumination. The building and instruments were presented to the University by Robert H. Sayre, Esq., July 23, 1903. Observations secured with this instrument are for the purpose of investigating the Variation of Latitude."
John Hutchison Ogburn. Results of observations with the Zenith telescope, from September 11, 1904, to September 1, 1905...