Maker, Warren Telechron, Inc., Ashland, Massachusetts, USA. Model Type E, c. early 1930's, serial no. 17.

One of the most compelling visual features of this clock is the large floor-standing aluminum and glass cylinder enclosure. It measures just under 5 feet tall and is needed for the clock to run in a partial evacuated environment. There have been a number of precision electro-mechanical master clocks designed to run in partial vacuum which were made for a relatively brief period covering twenty or so years from the 1920's  through the 1930's; before the advent of the fully electronic clock. The most famous and prolific makers being Clemens Riefler of Münich, Germany beginning in the early 1920's and William H. Shortt working with the Synchronome Company, London, England beginning in 1924. This example by Henry Warren was one of the last examples to arrive in the early 1930's. One can see the influence of the art deco period's sleek contours in the design of the clock movement and case. No other evacuated master clock was designed as floor standing unit, but were mounted to the wall. And no other example, with the one exception of a very rare model by Riefler, had the entire mechanism housed in a glass case. In all other instances the body was composed of a metal cylinder, usually copper with a small glass dome at the upper end where the pendulum was attached. The glass is in perfect condition and has a slight reddish iodine color tint. It is unknown if this was intentional or the result of age. It was made by Macbeth Evans glassworks which was founded in 1899 and bought out in 1937 by Owens-Corning glass works of New York. The lower cylinder has MADE IN USA, MACBETH, LUMITE A, etched on the surface. The LUMITE line of glass cylinders was used widely in the old style ten gallon retail gasoline pumps until their phase out in the late 1930's. This was a custom cylinder as it is 10.25" diameter and the gas pump cylinders were 12.5". Perhaps Henry Warren got the inspiration for the look of this clock while filling his car at the local gas station!

The photo below shows the base containing a control knob, left, that moves a permanent magnet located below where the pendulum bob swings. Since the base is made of aluminum it does not block the magnetic field. The bob, shown in the photo above is made of non magnetic material, but a split ring that fits tightly over the outside bob's cylinder is. This ring interacts with the magnet depending on its proximity to fine tune the pendulum's rate without having to open the evacuated cylinder. It is a conceptual holdover from his first master clock the Type A which used the same concept, but with an electromagnet located beneath the pendulum. The field strength of the magnet could be varied electrically. A valve for purposes of attaching a vacuum pump is located to the lower right.