Springs for Watches and Chronometers.
Year: 1888

page_text: Springs for Watches and Chronometers.
I, Paul Perret, of Chaux de Fonds, in Switzerland, Watch Manufacturer, do
hereby declare the nature of said Invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement, that is to say :-
Although the construction of the balance wheels and balance springs of watches is a
most important part of watch manufacture, it has not been as much improved as has
that of the other parts of the watch.
The whole mechanism of the watch is intended to transmit and to distribute
intermittently the power of the main spring with as little loss of force as possible.
The purpose of the balance wheel and balance spring consists essentially in
regulating those intermittencies.
To work satisfactorily, the balance wheel, as well as the balance spring, must be
made so as not to be influenced either by the variations of temperature, or by
magnetic influences. The influences of variations of temperature are eliminated by
forming the balance wheels of two metals, one of which has a higher coefficient of
dilatation than the other, and there have already been used non-magnetic alloys in the
manufacture of balance wheels and balance springs for the purpose of avoiding the
disturbances produced in the working of the escapement, by magnetic influences.
But the process of manufacturing compensated balance-wheels has not been
improved till now, and the process used till now, which is very long and complicated,
has likewise the disadvantage of producing a great waste of metal which is a most
important disadvantage in manufacturing non-magnetic balance wheels, because they
are essentially composed of precious metals.

page_text: Furthermore, I have improved the product itself, that is to say, the balance-wheel,
which differs in some points from the compensated balance wheels made till now.
My first improvement consists in making the arms and ring of the balance wheels
separately, and then fixing them to one another by screws, by soldering, or in other
suitable way.
In those cases in which I desire to obtain a very exact regulation of
the watch, I further divide the bimetallic ring of the balance into three segments, in
place of dividing the same, as usual, into only two segments. Above all, I make the
bimetallic ring, of the compensated balance wheel, in quite another way to what is
now the case. My process is the following: I first prepare or compose a metallic
alloy having the same properties and approximately the same coefficient of expansion
as steel, by melting together, in crucible-furnace, platinum and nickel, or iridio-
platinum and nickel, to which may be added a small quantity of silver, if it be desired
to have a white alloy...
The alloy so composed is formed into a rectangular ingot if it be intended to be
used for manufacturing. balance wheels, or into an ingot formed like a rod, if it be
intended to be used for manufacturing balance springs. The said ingot is then rolled
until it becomes approximately of the thickness of the inner blade of the bimetallic
ring of the balance-wheel which is to be formed, or exactly of the thickness of the
balance-spring which is to be manufactured. In the latter case, the balance-spring is
then finished by the usual process of making these springs.
For making balance-wheels I solder, by melting upon the above specified rectangular
ingot, another rectangular ingot of the same size, but formed of brass, or of another
metal being more dilatable than steel.
The so formed bimetallic ingot is then rolled and soldered into the form of a tube,
the inner wall of which is formed of steel, or of the above specified non-magnetic
alloy. This bimetallic tube may now be cut up into bimetallic rings which are turned
and polished in the lathe, and provided with the necessary screw holes.
The bimetallic tubo may likewise be made by soldering a tube of brass, or of similar
metal, over a tube of steel, or of a non-magnetic alloy having the properties of steel, or
in any other way.
The arms of the balance-wheel are made separately, and are affixed
to the aforesaid rings either by means of screws, or by soldering them, or in any other
suitable way.
When strongly affixed to the arms, the bimetallic ring is cut off at two or three.
places according to the number of arms, and the so formed balance-wheel works as
accurately as the best compensated balance-wheel made by ordinary processes.
In the accompanying drawings Figs. 1 and 2 shew compensated balance-wheels-
made according to my invention.
Having now described my Invention and in what manner the same may be
performed, I claim :
1. The process or method of manufacturing balance-wheels for watches or
chronometers, consisting in forming a bimetallic tube, in cutting up said tube into
bimetallic rings forming the ring of the balance-wheel, in fixing said rings to the
separately made arms of the wheel, either by screwing or soldering them, and finally
cutting the ring into two or three segments according to the number of arms of the
balance-wheel, substantially as described and for the purpose specified.
2. In the manufacture of compensated balance-wheels and balance-springs for
watches and chronometers, the composition of the inner blade of the bimetallic
balance-ring, or of the blade of the balance-spring, of an alloy of platinum and nickel,
or of iridio-platinum and nickel, with or without the addition of small quantities of
silver, substantially as described and for the purpose specified.
3. The bi-metallic tube formed of an inner tube of a less dilatable metal than the
outer tube, and producing, when cut up into bimetallic rings, the segments for
compensated balance-wheels for watches and chronometers, substantially as described
and for the purpose specified.

page_text: 4. A metallic balance-wheel for watches and chronometers, having its arms and its
segments made separately and connected together by screws, or other suitable means,
substantially as described and shewn.
5. A compensated balance wheel for watches and chronometers having its bimetallic
ring affixed to three arms and cut into three segments, substantially as described and
shewn and for the purpose specified.
Dated this 13th day of October 1888.
ERNEST DE PASS,
68, Fleet Street, London,
Agent for the Applicant.