IMPROVE- MENTS IN ALARM-WATCHES
Year: 1883

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the Commissioners of Patents on the 11th December 1883.
CHARLES MASMEJAN of Arogno in the Canton of Tessin Switzerland " IMPROVE-
MENTS IN ALARM-WATCHES
"
This Invention consists in the construction of alarm watches with keyless action
with only a single barrel whereby cheapness of manufacture is combined with
precision in setting.
According to this Invention the ratch of the winding differs essentially from all
those in use as it carries but one wheel which engages both with the stem wheel
and the ratchet of the barrel and its centre of motion is at the centre of the pillar
plate. A small lever is provided to allow the ratch to be disengaged for the
purpose hereafter described and a small spring is also provided to make it engage.
A bridge covers the whole and keeps it free in its place.
The hammer does not carry an anchor of a single piece but is provided with
two semicircular pins forming the two lever teeth of the recoil escapement which
sets it in motion. This very simple contrivance enables the working of this
escapement to be easily regulated by turning the pins more or less.
To set the alarum and hands there is provided under the dial another double
acting ratch carrying three wheels one of which constantly engages with the
stem-wheel being situated upon the centre of motion of the ratch. The other is
used for regulating the alarum by means of a push-piece which makes it engage
with a cannon wheel carrying on its upper side a small alarum dial similar to the
movable dials of common alarm-clocks and on the other side a disc with a notch
for the detent this cannon works upon that of the hour hand by friction.
The hands are set by the other push piece to effect which a wheel bears on its
cannon which traverses the bridge another smaller wheel engaging with the
minute wheel when the push-piece is acted upon. A spring keeps the ratch out of
gear on both sides.
The barrel which is very large as compared with the wheel-work can receive a
spring long enough to be wound 6 turns three of which at most are for the
alarum and the remainder enables the watch to go more than 30 hours.
The detent instead of working by lifting up the cannon wheel works sidewise to
set the alarum it is necessary to make the hour at which it must strike come under
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page_text: the hour hand of the small dial. This motion must be effected in the direction of
that of the hands namely by turning the crown to the left. As this motion does
not wind up the spring it can be effected without the aid of the small lever. But
to make the hands advance as it is necessary to turn to the right it cannot be
effected if the spring is already wound up therefore the ratch must be disengaged.
As the arbour of the barrel revolves when the alarum strikes it is also advisable
to put the ratch out of gear otherwise the stem turns also and the crown might
be stopped by the chain of the watch.
It is therefore advisable when the watch is placed on a night table for example
to bring the aforesaid lever into play. It will remain in that position because it is
slightly pressed by the bridge.
To avoid the striking of the alarum when the watch is in the pocket there is a
secret spring applied against the bridge of the barrel which stops the hammer
when the case is shut it is therefore necessary to leave the case open in order that
the alarm may strike or if desired this spring can be replaced by a lever in order
to effect the stoppage or striking at will when the case is shut