Watch′man's time-de-tect′or.
Fig. 7083 shows an instrument carried by a watchman who visits the various places on his beat where the keys are within reach.
Six keys are shown for as many watchmen, and when inserted in the watch will prick a hole at a point opposite to the hour at which the visit is made, and each man's record in his own row. See also
Fig. 7080.
The clock (Fig 7084) has a small central slate-edged dial over the main dial, and its face is protected by a plate of glass having a perforation large enough to admit a pencil, by which a mark may be made on the small dial; this is connected with and carried around by the hour-hand, so that the time at which each mark is made is shown; and if the watchman omits to perform this duty at the proper time, the absence of the corresponding mark shows the fact.
The marks are readily wiped off from the slate.
Paper dials, which may be filed away as records,
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Buerk's watchman's time-detector. |
can also be used.
a is a reverse view of the sub-dial, showing its means of connection with the clock.
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Watchman's time-detector. |
The time-indicator used on the
French railways (1853) is the invention of
M. Aresa.
It is also used in other public establishments guarded by police or watchmen.
A sort of tableclock is placed at a particular spot, at which the watchman must be at every quarter of an hour during his nightpa-trol; at that time he is required to press his finger on a stud or button, which is the only part of the apparatus at his command.
Beyond this he knows or does nothing in the matter; but when the clockcase is opened next day by a superintendent, a circular graduated card is found to be pierced with as many small holes as the guard had made pressures on the stud; and the card also shows the exact hour and minute when each hole was pierced.
The mechanism is very simple; the circular card or paper is made to rotate by connection with the hourwheel of the clock, and the button or stud acts upon a sharp needle, which pierces the card.
If the card is not pierced opposite to a particular quarter of an hour, the conclusion is drawn that the guard has failed in vigilance.
