IMPROVEMENTS IN THE MANUFACTURE OF WATCHES AND CLOCKS
Year: 1861

page_text: PROVISIONAL SPECIFICATION left by Jean Auguste Petit at the Office
of the Commissioners of Patents, with his Petition, on the 6th August
1861.
I, JEAN AUGUSTE PETIT, of 17, Red Lion Square, in the County of Middle-
sex, Watch and Clock Maker, do hereby declare the nature of the Invention
for "IMPROVEMENTS IN THE MANUFACTURE OF WATCHES AND CLOCKS," to be as
follows:-
My improvements in the manufacture of watches and clocks have reference
to seven principal points:-First, the escapement; second, the repeater;
third, the minute hand; fourth, the spiral; fifth, the spring barrel; sixth, the
alarum; and, seventh, the pillars.
My new escapement is so disposed as to facilitate its adjusting. To this
effect a slide rest that slides round the pinion leading the escape pinion brings
the escape wheel nearer to or removes it from the anchor; besides, the escape
wheel is so formed as to let the pallets of the anchor slide down on an inclined
plane of the said wheel, and to effect a recoil in case a strong jerk should so
much shake the balance that the ruby pin of the disc or roller would come in
pression against either of the outer parts of the forks. In fact the ruby pin
of the disc could then pass on unopposed through the internal inclined plane
of the said escape wheel; for since it permits either of the two pallets of the
anchor to slide down towards the centre of the wheel, the fork in the same
time recedes on either side from the axle of the balance. Let it be under-
stood that the roller is only destined to hold the ruby pin, and may be indis-

page_text: criminately placed either on the support or even on the balance, for it has no
other mission than to effect the detent and to receive the impulse. The
impulse planes of the escapement are divided in two unequal parts, the
shorter one being formed on the pallets of the anchor and the longer one on
the teeth of the wheel. The pallets may be in the shape either of a perfect
circle or of a truncated circle; they may be fixed by one end or by both ends.
The curve of the external inclined planes of the teeth corresponds to the curve
of the whole circle of the wheel. The internal inclined plane produces the
recoil in case of a jerk.
Second, my repeater is remarkable by the extreme simplicity of its pieces,
the number of which I have considerably reduced. For instance, I dispense
with the barrel and its spring mover, and the wheel works specially adapted to
ordinary repeaters.
My improvements may be explained in the following manner:-Three
rattles mounted on the same axle serve to take the time when the detent is
relaxed. One of these rattles takes the hours from a snail fixed upon the
hour wheel, another rattle takes the twelfth parts of the hour, say, the five
minute fractions, from a snail fixed upon the minute wheel, and a third rattle
takes the minutes from a third snail mounted on the same minute wheel.
The change in the striking of the hour, five-minute fractions, and minutes, is
effected by a click that is terminated by a piece having three faces, each of
them corresponding to each change of the striking. When the hour has
struck this piece is lowered for the striking of the five-minute fractions, and is
still more lowered for the striking of the minutes, and it retakes its position
when the detent is acted upon. The detent is worked as usual. But the
ringing is effected by pressing upon a knob till the end of the ringing. The
first ringing indicates the hours, the second ringing indicates the five-minute
fractions, the third ringing indicates the minutes. Each ringing is effected in
a different manner. For instance, the hammer will strike once for the hours,
twice for the five-minute fractions, and again once for the minutes, every
change being clearly indicated by some marked interval. My system has the
advantage of giving the exact time to a minute with a number of pieces less
than in the other repeaters. So supposing it to be seventeen minutes past four,
the four first pressions of the finger upon the knob will obtain a single strike,
marking an hour each, say, four hours; under three other pressions three
double ringings will indicate three five-minute fractions, say, fifteen minutes;
two more pressions of the finger will call two single ringings, say, two minutes,
making in all four hours and seventeen minutes. My system, besides, only
requires one hammer.

page_text: Third, the minute hand is, according to my system, fixed on the minute
wheel by means of a screw, which traverses it through one of its sides, and
gets in a small circular groove indented all round the rod of the centre wheel.
The function of this screw is, first, to fix the hand on the minute wheel, and,
secondly, to fix the minute wheel on its own rod.
Fourth, I have found it convenient to fix the end of the spiral by means of
a steel spring pincher tightened by means of a screw.
Note. The above-mentioned improvements are applicable to watches as
well as to clocks. The herein-after described improvements are more parti-
ticularly applicable to clocks, and especially to alarums.
I increase the size of the spring barrel, and I so obtain a motive power
more constant. Moreover, by a new disposition of the frame this barrel may
be removed without it being necessary to take the clock to pieces, which gives
great facility to regulate or repair the motion spring. The barrel wheel is
fixed to the barrel by means of two screws, one of which has, besides, the
mission of fixing the stop wheel between the barrel and the said wheel. The
stop finger and the arbor of the barrel are as a single piece. Although
the diameter of the barrel is increased the diameter of its wheel retains its
ordinary dimensions.
Sixth, I dispense with the especial barrel and spring of the alarum. They
are replaced by a toothed circle, or a portion of a toothed circle, acting as a
single piece, with a click mounted on the axle of the spring barrel. The
function of this circle or portion of circle is to give motion to the alarum
wheel work. To obtain the alarum it suffices to wind up, either directly with
the hand or by an external communication, the toothed circle or portion of
toothed circle.
Seventh, the pillars of the plates in my system serve also to fix the dial
plate. To this effect the screws which fix the pillars on the lower plate form
the pillars of the dial plate, and the whole is fixed by screws or nuts.