Riefler Prescision Regulator Clock
This pendulum clock served as the first time standard in the United States, from 1904 to 1929. It achieved accuracies of 10 milliseconds per day, and were guaranteed to be at least within 30 milliseconds. By including a low thermal expansion pendulum, a low pressure tank, and a gravity remontoire, the error on the pendulum swing was reduced.
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Coordinates
Latitude: 38.921261200000
Longitude: -77.066520000000
Longitude: -77.066520000000