Dudley Observatory

The Dudley Observatory was incorporated in 1856 as part of an ambitious plan to create a university in Albany that would rival those of Europe. The university did not materialize at that time but plans for an observatory received popular backing as well as support from wealthy Albany residents, including the banker Thomas Olcott and Blandina Dudley, widow of the Observatory’s namesake politician Charles Dudley.

In 1905, the Dudley Observatory became the Carnegie Institution’s Department of Meridian Astronomy, responsible for creating the largest and most accurate star catalogue yet produced.  For the next thirty years, the Dudley focused on measuring star positions by recording the exact time that a star passed a certain meridian. Since no single measurement was guaranteed to be accurate, the recording had to be repeated night after night for months. A clock that could keep time consistently across those months was essential for determining accurate star positions.

This bracket-mounted clock, manufactured by the company of Clemens Riefler in Munich, Germany, was simply the most accurate timepiece of its era. Originally stored in a sealed glass cylinder and kept in low pressure to reduce the effects of atmospheric shifts on the accuracy, Riefler clocks were accurate to within 10 milliseconds per day. These clocks were used by observatories and timekeeping services, and the first U.S. standard time was supplied by Riefler clocks from 1904 until 1929.

This particular clock was bolted to a wall in Dudley’s Lake Street Observatory, providing reliably accurate time through a telegraph wire to less accurate clocks, chronographs, and other astronomical instruments.


Magnifying Glass
Precision Wall Clock
Manufactured by Clemens Riefler, Munich, Germany
Brass, iron, paint, glass
Courtesy of Dudley Observatory
Magnifying Glass
Dudley Observatory Dedication, August 28, 1856
Tompkins Matteson
Oil on canvas
Albany Institute of History & Art, gift of General Amasa J. Parker, 1917.3