Shortt pendulum clock

The Shortt pendulum clock, invented by William H. Shortt, is a highly accurate clock that utilizes an improved free pendulum. It consists of two synchronized clocks. The primary timekeeping element is a pendulum that swings freely, receiving a gentle impulse from a falling lever every half minute. This lever is released by an electrical signal from a slave clock. After the impulse, a synchronizing signal is sent back to the slave clock to ensure the next impulse is precisely timed. The pendulum operates within a sealed, low-pressure box to maintain accuracy. Shortt clocks, kept in temperature-controlled rooms, can maintain time within thousandths of a second per day.12