The watchman's clock was installed with a clock and an alarm.

The watchman on duty was responsible for marking a point on the clock at fixed intervals to prove that he was awake and watching for fires all the duty time.

If he did not mark the clock, an special alarm would ring in the fire station to alert others that there was a problem.

A fireman's wages would be docked or fined if he did not mark the clock properly. This strict rule ensured that the fireman stayed awake and watchful throughout their duty shift.