Improvements in Balances and Balance Springs for Watch, Clock, and like Escapements.
Year: 1897

page_text: COMPLETE SPECIFICATION.
Improvements in Balances and Balance Springs for Watch, Clock, and
like Escapements.
I, PAUL PERRET, of Chaux-de-Fonds, in the Republic of Switzerland, Watch
Manufacturer, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and by
the following statement:-
This invention relates to improvements in balances and balance springs for all
kinds of escapements for watches, clocks and the like and it consists mainly in a
balance or hair spring made of an alloy possessing the property of increasing its
elastic force in proportion as the temperature rises so that an ordinary balance can
be employed for the escapement, that is to say, a non-compensation balance. The
increase in elastic force of the metal constituting the balance spring with the rise
in temperature should be sufficient to compensate for the increase of the moment
of inertia of the balance due to its expansion.
The balance spring can be made, for example, by combining steel and nickel,
the proportion of the metals depending upon the nature of the metal or alloy
employed for the balance.
With a brass balance, the following proportion for the balance spring can be
adopted; about 72 parts by weight of steel and 28 parts by weight of nickel. With
a balance made of an alloy which only slightly expands and composed of 35 to 36
parts by weight of nickel and 65 to 64 parts of steel, the proportion of 73 parts by
weight of steel and 27 parts of nickel, gives good results.
Other metals than steel and nickel can be combined for producing the required
effect. It is preferable to select those alloys which are the most advantageous in
so far as regards the effects of oxidation and magnetism.
°
Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed, I declare that what I
claim is:-
1
1. A balance spring for the escapements of watches, clocks and the like, made
from an alloy having the property of increasing its elastic force with a rise of tem-
perature for the purpose of obtaining a compensation for the expansion of the
balance which consequently need not be a compensation balance.

page_text: 2. In an escapement for watches, clocks and the like the conbination with an
ordinary balance, that is to say, a non-compensation balance, of a balance spring of
the usual form made of an alloy having the property of increasing its elastic force
with a rise of temperature, with the object of obtaining a compensation for the
expansion of the balance.
3. A balance spring of the kind referred to in Claim 1 made essentially of an
alloy formed of 73 to 72 parts by weight of steel and 27 to 28 parts of nickel.
4. In escapements of the kind referred to in Claim 2. a brass balance and a
balance spring made of an alloy of about 28 parts by weight of nickel and 72 parts
of steel.
5. In an escapement of the kind referred to in Claim 2 a balance spring made
of an alloy of about 27 parts by weight of nickel and 73 parts of steel, and a balance
formed of an alloy which only slightly expands made of 35 to 36 parts by weight
of nickel and 65 to 64 parts of steel.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.