Tell-tale clock

Fig.4770, Watchman’s electric tell tale clock.
20 channels, 7 days chart. “Slave” edition, c. 1945.
The interior picture shows the movement behind the dial and the horizontal one with the gear that drives the drum. Left from the drum the markers. When the watchman, making his patrol, turns his key in one of the contact boxes, this marks the chart, so that a complete charted record is available of all the points visited, and the times they are visited, for examination and investigation of any default.

 

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Above: Every time  when the paper on the drum is changed, a gearing automaticilly forwards the ink ribbon a bit
  
Left: the ineriour of the Watchmansclock, note how the slave with its gearing slowly moves the (7 days) drum forward.