Post or sidewalk clocks were first commercially produced in the United States c. 1870. The clocks were available in two- or four-dial models from 30 in. To 40 in. In diameter, supported on decorative cast-iron frames, usually measuring 12 to 15 ft. From base to dial centers. The clocks made by E. Howard Clock Co. Of Boston had the pendulum movement mouted in a compartment about street level. These were eight-day, weight-operated timepieces, with a locked door at the base opened weekly for winding. The A. S. Hotchkiss of New York models had the movement placed in an adjoining building and connexion was made under the sidewalk. Illuminated plate-glass dials were available. Tower and sidewalk clocks were continued to be manufactured during the first quarter of the 20th century. Many sidewalk clocks were later electrified.