Improvements in Balances and Balance-springs for Watch, Clock, and like Escapements.
Year: 1898

page_text: Date of Application, 24th May, 1898-Accepted, 2nd July, 1898
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, Manu-
facturer, 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
watch, clock and like escapements.
In the Specification of my former Patent No. 25142 of 1897 I have described a
novel escapement for watches, clocks and the like in which an ordinary balance
wheel, that is to say non-compensated, is combined with a balance or hair-spring
of ordinary form and composed of an alloy consisting of 27 to 28 parts of nickel and
73 to 72 parts of steel, the said spring having the property of increasing its
elasticity with the rise of temperature so as to compensate for the expansion of
the balance.
I have since found that the same results can be obtained by forming the spring
of this non-compensated escapement balance of an alloy of steel and nickel wherein
the proportion of nickel is comprised between 38 and 45 per cent.
With a non-compensated balance of brass, the spring can be made of an alloy
of nickel and steel containing about 43'5 per cent. by weight of nickel and with a
non-compensated balance of a metal which only expands slightly and composed
of 35 to 36 parts by weight of nickel and 65 to 64 parts of steel, the spring can
be formed of an alloy of nickel and steel having about 44 per cent. by weight of
nickel. The proportion of nickel in the alloy forming the spring may be varied
within certain limits, for example from 38 to 45 %, it being understood that the
elasticity can be modified by drawing and even in the manufacture of the spring.
A spring made of this alloy of steel and nickel, in which the proportion of nickel
is comprised between 38 and 45 per cent., does not oxidize quickly and its elasticity
increases more regularly with rise in temperature than that of a spring in which
the proportions of nickel are those described in my said Patent No. 25142 of 1897.
By "nickel" I mean commercial nickel and not the chemically pure metal.
The alloy forming the spring normally contains small quantities of carbon,
manganese and silica. A small fraction of the nickel can be replaced by a
practically equivalent quantity of chromium. Other bodies can also be incorporated
in the alloy to modify its hardness or its elasticity.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
1. A balance or hair-spring for watch, clock and like escapements, formed of
an alloy of nickel and steel containing 38 to 45% of nickel and 62 to 55 % of steel,
substantially as, and for the purpose, herein before described.
2. An escapement comprising a balance of ordinary construction, that is to say,
non-compensated, combined with a spring of ordinary shape and made of an alloy

page_text: of nickel and steel having 38 to 45 % of nickel and possessing the property of
increasing in elasticity with rise in temperature for the purpose of compensating
for the expansion of the balance.
3. An arrangement of the kind described in the preceding claiming clause, com-
prising a brass balance and a spring composed of an alloy of steel and nickel, of
which the nickel forms about 435 % by weight.
4. An escapement of the kind described in Claim 2 and having a spring com-
posed of an alloy of steel and nickel, of which the latter forms about 44% by
weight, and a balance formed of an alloy which only expands slightly and is com-
posed of 35 to 36 parts by weight of nickel and 65 to 64 parts of steel.
Dated the 23rd day of May 1898.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.