They were of unusual design, each with a pendulum 13 feet (3.96 metres) in length mounted above the clock face, giving a period of four seconds and an accuracy, then unparalleled, of seven seconds per day.
Длина маятника составляла 13 футов (3,96 м), период колебаний — 4 секунды, погрешность хода часов — семь секунд в сутки.