overall: 44 1/2 in x 20 in x 17 1/2 in; 113.03 cm x 50.8 cm x 44.45 cm
clock; Electronic (Quartz); Free-Standing Clock
This clock was built at the U. S. Naval Observatory about 1936 as part of an experimental program to control time signals transmitted by radio. It is a quartz clock, that is, it depends on a specially cut piece of quartz crystal to keep time. The search for a better timekeeper than the best pendulum clocks led to the development of quartz-crystal clocks, the first of which telecommunications engineers at Bell Telephone Laboratories built in 1927 to monitor and control frequencies.