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Hipp toggle battery clocks, so named after the inventor Matthaus Hipp around 1844, were widely copied in principle. The pendulum swings freely until its momentum slows so that a toggle catches in a narrow slot extending from the pendulum rod lifting the moveable electrical contact so that it wipes its mating contact on the pendulum rod completing the circuit to the electromagnets, thus providing a propelling force to the pendulum. The advantage is increased timekeeping accuracy because the pendulum swings freely and receives impulse force only when the stroke decreases to a predetermined relationship between the toggle and notch. The pendulum motions are "counted" by a ratchet and pawl to move the hands around the dial and is designed to have a minimum friction loss. Hipp toggle type clocks enjoy excellent long-period accuracy but are not desired for timing short periods of a few minutes or fractions of minutes. The period of the pendulum strokes, although on average is very constant, varies between propelling impulses. In this example, the ratchet wheel is in the form of a pin wheel. The dial hands motion gear train is incremented by another ratchet and pawl so that the minute hand moves only between the 58th and 60th second of each minute. The same mechanism switches alternating polarity electrical impulses for secondary or slave dials remote from the master clock. Electrical power if 12 volts is supplied by a battery. Johann Meindl, whose name appears on the face of this example, is a family member of Austrian clockmakers in Vienna. That this clock was made by Meindl is uncertain, but examples of Meindl clocks other than battery powered are well documented. Many variations of the Hipp toggle clocks were made in large and small quantities by many clockmakers, some obscure, some well-known.
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