Telechron

Telechron is the name of a U.S. company that manufactured electric clocks between 1912 and 1992. "Telechron" is derived from the Greek words tele, meaning "far off," and chronos, "time," thus referring to the transmission of time over long distances. Founded by Henry Ellis Warren, Telechron introduced the synchronous electric clock, which keeps time by the oscillations of the alternating current electricity that powers it from the electric power grid. Telechron had its heyday between 1925 and 1955, when it sold millions of electric clocks to American consumers.

Henry Warren established the company in 1912 in Ashland, Massachusetts. Initially, it was called "The Warren Clock Company," producing battery-powered clocks. These proved unreliable, however, since batteries weakened quickly, which resulted in inaccurate time-keeping. Warren saw electric motors as the solution to this problem. In 1915, he invented a self-starting synchronous motor consisting of a rotor and a coil, which was patented in 1918. A synchronous motor spins at the same rate as the cycle of the alternating current driving it. Synchronous electric clocks had been available previously, but had to be started manually. In later years, Telechron would advertise its clocks as "bringing true time," because power plants kept the frequency of the alternating current perfectly constant at 60 Hz.

But such constancy did not yet exist when Warren first experimented with his synchronous motors. Irregularities in the frequency of the alternating current led not only to inaccurate time-keeping but, more seriously, to incompatible power-grids in the U.S., as power could not readily be transferred from one grid to another. In order to overcome these problems, Warren invented a "master clock," which he installed at the Boston Edison Company in 1916.

This master clock had two movements, one driven by a synchronous motor connected to the current produced by the power plant, the other driven by a traditional spring and pendulum. The pendulum was adjusted twice a day in accordance with time signals received from the Naval Observatory. As long as the hands of the electric clock, powered by a 60 Hz synchronous motor, moved along perfectly with those of the "traditional" clock, the power produced by the electric company was uniform. In Electrifying Time, Jim Linz writes that "in 1947, Warren Master Clocks regulated over 95 percent of the electric lines in the United States."

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