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Any typos are as a result of direct translation of the
original French.
Small history:
During second half of the 18th century, when one introduced a needle of seconds
on the watches of pocket, one sought a device allowing to stop it.
At the beginning, the solution was to stop the movement, using a small lever.
About 1800-1840 one added a complete movement for the seconds, having his own
barrel, whose its only function was to ensure the rotation of the needle of the
seconds which carried out a jump every second (dryness dead).
A first stop watch (recording of time) was invented by Rieussec in 1821-22, it
was equipped with a revolving dial and a mechanism of inscription to the ink
which made points or features on the dial.
In 1832 Rieussec proposed a stop watch with revolving needle and fixed dial.
It also made stop watches of pocket which had two sets of wheels including one
for the normal watch and the other for the stop watch.
Later Auguste Baud mounted the mechanism of stop watch on the bridges side wheel
and several meters were added (minutes and hours).
What a stop watch?
For all things it is necessary to pay attention not to confuse a stop watch and
a stop watch, a confusion still quite present among people.
The stop watch is a
time apparatus of precision.
The stop watch is a
time apparatus which makes it possible to take a measurement of time.
A stop watch is a time apparatus, in the particular case a watch, having a
needle placed at the center of the movement.
This needle, named "second hand", can be at will:
- starting, stopped, then brought back to its starting point.
These three functions are operated by means of a mechanism known as of stop
watch.
- At the time or one a first pressure on the push rod of the stopwatch the
second hand exerts is started and advances by small regular jump.
- A second pressure on the push rod causes to stop the second hand at the
precise point where it was at the time of the pressure.
- By a third pressure, the second hand returns quickly to its starting
point; i.e. on division zero of the dial.
These three functions which we have just described name:
- The departure.
- The stop.
- Restoring.
Simple stop watch at three times.
Terminology:
| With |
Coil with columns |
K |
Rock intermediate |
| B |
Hook |
M |
Brake |
| C |
Large rocker (Order) |
N |
Comes out from brake |
| D |
Heart of restoring |
R |
Eccentric of rocker |
| E |
Comes out from hammer |
T |
Saltire of wheel with columns |
| F |
Coil on field |
U |
Comes out from large rocker |
| G |
Intermediate gear |
V |
Comes out from intermediate rocker |
| H |
Coil stop watch |
1, 2, 3 etc... |
Columns |
| J |
Hammer |
Moment of the explosion
So that a stop watch functions correctly, it is necessary that the various
rockers are actuated at one precise time.
When one presses on the push rod of stop watch, the hook actuates the wheel in
the direction of the arrow.
The point of tooth "A" goes up on tilted "the bc" of the
saltire, until the moment when the point "has" tooth comes into
contact with the top "C" of the saltire.
The moment when the two points are in contact names:
"moment of explosion" .
 At
the time or a tooth of the wheel exceeds the point of the saltire, it is the
tilted one of this one which completes to make turn the wheel to columns to
position it correctly.
If
tilted the bc of the saltire is accentuated too much, it will make the push
rod hard and the moment of the explosion will be delayed.
If
tilted the bc of the saltire is not accentuated enough, it will be too soft,
it will miss clearness and it will not position the tooth of the ratchet.
Operation:
The function "departure" 
A
pressure carried out on the large rocker (P), causes the drive of the wheel
with column by the intermediary of the hook in the direction of the arrow.
Column 5 raises the hammer.
Column 1 on which the nozzle of the intermediate rocker rested being
withdrawn, the rocker actuated by its spring goes down between column 1 and 2.
The
intermediate gear G gears with the wheel of stop watch H .
The
brake remains raised.
The
second hand is started.
The function "stop"
One
2nd pressure on the push rod of stopwatch causes the withdrawal of column 3,
the nozzle of the above being brake, via its spring goes down between columns
3 and 4.
Column 2 raises the nozzle of the intermediate rocker, from where rupture of
gears enters the intermediate gear and the wheel stopwatch.
The
hammer remains raised.
The
needle second hand stops.
Note:
The brake must
go down at the time from the explosion or very slightly afterwards.
If it goes down
front, it will come to rest against the circumference of the wheel stopwatch
before the intermediate rocker is not released, which will cause the stopping
of the stopwatch and the watch.
If the brake
goes down after the moment from the explosion, its action will be attenuated
because it must even block the wheel stopwatch at the time or the intermediate
gear is withdrawn.
With the stop,
the rocker interm. does not have to be raised by column 2 before the moment of
the explosion, but slightly afterwards. If the rocker rises before the moment
of the explosion, one can stop the stopwatch by a light pressure on the push
rod.
The function "Given to zero"
At
the time of one 3rd pressure, column 4 actuates the nozzle of brake which
releases the wheel of stop watch.
The
nozzle of the hammer being presented opposite the vacuum between two columns,
the hammer goes down, actuated by its spring and comes to support on the
circumference of the heart, to carry out the restoring.
The
nozzle of the intermediate rocker remains raised by the column.
The
brake must rise before the hammer does not go down, because the wheel of stop
watch must be released when the hammer goes down on the heart in order to
bring back the second hand to zero.
Summary of the functions of the stop watch:
At the beginning:
- The hammer rises as quickly as possible.
- The intermediate rocker goes down the latest possible (in all the cases
after the moment of the explosion).
- The brake remains raised.
With the stop:
- The brake goes down at the time from the explosion or slightly afterwards,
but before the intermediate gear is released from the wheel of stopwatch.
- The intermediate rocker rises after the moment of the explosion.
- The hammer remains raised.
With the restoring:
- The brake rises.
- The hammer falls the latest possible.
- The intermediate rocker remains raised.
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