Grand Master Clock, International Time Recording Company, Division of IBM, Patented 1921
In 1927, a system of clocks was installed in the new Georgian buildings on East Campus. This Grand Master was in the East Duke Building and controlled a master in each building, which, in turn, controlled subsidiary clocks in individual rooms of East Campus buildings. When a clock ran fast or slow during an hour, the Grand Master automatically corrected it on the hour. Even when the power failed, the Grand Master continued to run.
The clocks operated on a three-wire system using direct current. One wire ran the bell system and another, the clocks. The third neutral wire completed the circuit. Bells on the wheels in the master clocks in each building triggered bells in the subsidiary clocks to announce the beginning and end of class periods. This Grand Master, with a mercury pendulum, was patented in 1921. It was manufactured by the International Time Recording Company, a division of IBM. The Grand Master Clock is located in the small lobby before the entry into the Reference Room (Room 105 on the main floor).
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