This is a battery powered clock movement by the Self Winding Clock Company of New York.
Self Winding Clock Company History
This company was formed in 1886 by Charles Pratt with Henry Chester Pond. The design was based on automatically winding the clock each hour with a motor powered by two 1-1/2 volt dry cells located in the case.
The advantage of this high-quality, pendulum-controlled movement, combined with the constant driving force of the small, frequently wound mainspring, was that it yielded a highly accurate clock subject to minimal wear.
An optional attachment allowed the clocks to be synchronized by hourly U.S. Naval Observatory time signals sent over Western Union telegraph lines. The railroads needed to coordinate among their stations (and among each other lest two trains sharing a stretch of track shared it too closely).
In 1883, the Naval Observatory agreed to telegraph standard railway time, a great boon for Western Union, who would then install and maintain the machines for a monthly fee.
These clocks were common in government offices, schools, and other institutions and could be seen in all Western Union telegraph offices.
This is a related and interesting piece by Neal McEwen: “Time, Standard Time, and Western Union.”
I run this clock using two 1.5v batteries in series. The clock is very large and heavy!
Read a bit about our other self-winding clock here.