Image: Howard astronomical regulator clock

Description: Drawing of a precision astronomical regulator clock made by the E. Howard Clock Co., from a publication by Lick Observatory, CA, USA, 1887. The clock had a pendulum consisting of 4 containers of mercury that compensated for thermal expansion of the pendulum rod with temperature changes. It had a deadbeat escapement. It was installed at Lick Observatory and served to generate electric time signals that were distributed by telegraph wire to railroads and factories in the city of San Jose. For this it had internal switch contacts that generated signal every 2 seconds, connected to the 4 electrical terminal posts seen at the top of the clock. Alterations to image: cropped out second drawing showing clock with case open, and caption, which read: "The Howard mean-time clock".
Title: Howard astronomical regulator clock
Credit: Downloaded 2008-11-26 from Edward S Holden (1887) Publications of the Lick Observatory of the University of California, Vol.1, Lick Observatory Trustees, p.72 on Google Books.
Author: Edward S. Holden
Permission: Public domain in US - published prior to 1923 in US
Usage Terms: Public domain
License: Public domain
Attribution Required?: No