The housing was octagonal in shape and included a semi-cylindrical annex. The upper and lower levels of the annex contained a tank which provided a constant head of water. Beneath it was a cylinder with a float. Water in the upper tank fed a slow drip into the lower cylinder. This caused the float to vary at a constant rate. A chain attached to the float ran by a series of pulleys to a weight. This in turn governed the motion of the main mechanism of the clock.