Measuring Stars, Time and Temperature

The Winchester Observatory


University observatories were the centers of research for modern astronomy in North America in the 19th century, but by the late 1800s many were faced with both economic and practical setbacks. Constructed in 1880, Yale College's first purpose-built observatory, also known as the Winchester Observatory, was no exception.

The Yale Observatory's economic difficulties came on the eve of the highly anticipated 1882 transit of Venus, a rare astronomical event that would allow astronomers to measure the distance from Earth to the Sun. The observatory had obtained enough private donations to buy a new telescope and heliometer (an apparatus used to measure the diameter of the Sun) with which to observe the transit, but still lacked minimal operating funds.

Photograph courtesy of Manuscripts & Archives, Yale University Library.

Six-inch heliometer made in Germany by Georg Repsold, purchased for the Yale Observatory in 1882.

Inset: Notes recorded during the transit of Venus in 1882 by Jefferson Engel Kershner at the Yale Observatory. Measurements of the sun's diameter taken by "observer" Leonard Waldo using the Yale Heliometer. Clock and
barometer readings are recorded throughout these notes.


During the transit four astronomers used five different instruments. One of these was a photoheliograph apparatus, used by R.W. Wilson to photograph the transit onto glass plates, an example of some of the then newest technologies applied to view the transit of Venus in North America.

The director of the observatory, Hubert Anson Newton, established two commercial enterprises to support its research activities: a Horological Bureau and a Thermometric Bureau. Through the horological service, Yale's "astronomer-in-charge" Leonard Waldo sent regular time signals by telegraph to a team of German astronomers observing the transit of Venus in Hartford, Connecticut, enabling them to accurately measure the speed of Venus's transit across the Sun.

Photograph courtesy of Department of Astronomy, Yale University, 1933. Notes courtesy of the Yale Astronomy Library

Astronomical Regulator donated by William Hillhouse in 1853. The outer dial is divided into minutes, the upper dial for seconds and the lower dial for hours. Reportedly made by Appleton in London. No date. YPM catalog no. 1.424B.


William Hillhouse donated an astronomical regulator to the Yale Observatory in 1853, more than 20 years before the observatory was built. Until then the clock was used in the observatory tower of Yale's Sheffield Scientific School. Hillhouse also donated a transit instrument, to encourage the president of Yale College to build a formal observatory

Instrument makers and doctors from Boston to Philadelphia sent thousands of thermometers to the Yale Observatory. Each thermometer was tested and issued a certificate of verification with a list of corrections. The observatory also began selling its own crystal standard thermometers made in Paris. Each sold for $30.00. Buyers included the United States Navy, which used them to improve the quality of its meteorological measurements and to study the effect of temperature on instruments like clocks and telescopes.

The Yale Observatory standard thermometer, no. 77, made by Tonnelot a Paris, January 1885. Crystal glass tube.
YPM catalog no. 5.1460


The Yale Thermometric Bureau was, at the time, the only such service of its kind in North America. One benefit was Waldo’s study of thermometer glass, which led him to campaign to prevent newly made clinical thermometers from being sold immediately after manufacture: because glass needs time to return to its natural density after being worked, a thermometer used too soon could give higher than normal readings, leading to incorrect diagnosis and possibly death.

Funding provided by these two services — a Horological Bureau and a Thermometric Bureau — significantly improved the observatory’s ability to obtain better instrumentation for accurate astronomical measurement. In addition to their role at the observatory, these bureaus were important in improving the quality of clocks and thermometers being made in the United States. The Horological Bureau was a subscription service used by New Haven City Hall, Connecticut telegraph exchanges, the railroad and local companies. Watchmakers and clockmakers also paid the bureau to correct their instruments and to issue certificates of verification that guaranteed quality and accuracy.

However, by 1900, the Yale Observatory faced a short-term identity crisis with the death of Newton and the pending retirement of director W. Lewis Elkin, who had produced the Catalogue of Yale Parallax Results. It also lacked long-term funding. The astronomy program was eventually renewed and moved to new observing stations in Bethany, Connecticut, and in the southern hemisphere. The bureau services never recovered. The largely unused observatory was repurposed in the 1960s and later demolished.

Visit the Division of Historical Scientific Instruments to see other items in the Yale Peabody Museum's collections.