International Master Clock
Circa 1939
In the 1940s and 1950s this International Master Clock was very popular with schools. It was very accurate and easy to opperate.
It was small for a master clock at only 43 inches high. The alder or cherry case was very plain but easy to care for and clean.
The dial was easy to read and even though the clock was very industrial looking, it did not look bad in principal's office. The only problem with it
was that they were fairly noisy. Every 60 seconds you would hear a solenoid thump as the propram plate would advance 1 minute. At the same time, every
slave clock in each of the class rooms would advance 1 minute.
The program plate had notches where you could place brass tabs for a 24 hour period at 1 minute intervals. When the tab would reach
the control panel, it would move a lever that would close a contact. The contact would ring the school bells.
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Slave clocks similar to the one above could be placed through out a building and if they were hooked to the master clock, every 60 seconds
the minute hand would advance 1 minute.
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