Posted 5 years ago
This is the first of the electric Big Ben alarm clocks, introduced in mid 1931 and marketed through 1934. The clock pictured, Model 820, has a black Bakelite case. Model 830 with luminous numerals and hands, and Model 840 with a mahogany case, were introduced at the same time. They are powered by Sangamo self-starting synchronous motors. The motor runs the clock as well as winds the alarm mainspring. There is a key on the back for manually winding the alarm mainspring. Designed by Martin H. Kaefer.