Maker, Warren Telechron, Inc., Ashland, Massachusetts, USA. Model Type A, serial no. 454, c. mid 1920's. Originally set up at the Nut Island, Virginia. sewerage treatment facility.

This model of master clock was the first type introduced by the Warren company in 1916 and was little changed until the late 1920's when it was replaced by the cheaper Type B. The company eventually ended it's master clock production with the Type E. It is a precision mechanical clock that is kept wound electrically. It's function was to act as a reference to monitor the accuracy of the a/c line frequency. The bottom dial is a regular clock driven by the mechanical master clock movement. The center dial has two superimposed hands. One a  black hand driven by the mechanical movement and the second, a gold hand driven by a synchronous motor. The dial is divided into five one minute sectors. Both hands move at the speed that a second hand would. The upper dial is driven by a second synchronous motor whose hand also moves by the second; its' dial is the same as the center. This was used as a backup in case the main synchronous motor should fail or need service.

This clock was very easy to use. All the operator needed to see was that both the black and gold hands on the main dial were super-imposed upon each other to know that the line frequency was correct. Any deviation left or right could be read directly off the dial and would let the technicians know by how much fast or slow the generators had to be adjusted to keep the line alternating current (a/c) at 60 cycles/second. This works because a synchronous motor will turn at the speed (frequency) of the alternating current that is powering it. Hence the name synchronous. Through reduction gearing the motor which turns 60 times a second is made to turn the gold hand at the speed of once per minute.

An interesting reversal of roles is now in effect. The modern generating plants of today keep their current frequencies quite accurate using electronics that are far better than a mechanical clock. So today the gold hand connected to the synchronous motor is used to monitor the accuracy of the mechanical master clock rather than the other way around as was the original intent! The movement is quite accurate down to less than a few seconds per week.

Control panel containing power knife switches for electrical motors. Setting and speed adjustments for pendulum. The pendulum has a metal bar at its' base and swings over a coil located on the floor of the clock. The Rheostats control current to the coil and therefore can slow the rate of the pendulum. In reality, the movement can be quite well regulated using the bob adjustments and the small weights that can be added or subtracted from the pendulum rod's weight pan.

Restoration photos, before shots. There was a fair amount of corrosion on the movement. Probably as a result of the harsh environment of a sewer treatment plant.

After