The watchman made his registration on this simple clock by writing his name on the portion of the chart exposed through the slot. Although this is about the most basic
watchclock there could be, it seems not to have evolved as a product particularly early. Why there are two slots is unknown. Similar models by others had only one slot.
This unit was imported by
Newman Clock Company as a sample after World War One. Note that it is numbered less than 700 numbers before I.D. 218. All Schlenker-Grusen watchclock movements seem to have been numbered in one continuous number
series. Generally, but not universally, a clock takes its serial number from that of the movement.