Clock Balances and the Strength of Balance Springs.
Year: 1886

page_text: Date of Application, 30th Apr., 1886
Complete Left, 31st Jan., 1887.
Complete Accepted, 1st Mar., 1887
Clock Balances and the Strength of Balance Springs.
We, GUSTAVE CORNTOLEY of the firm of Henri Picard et frère of 26 and 27
Bartlett's Buildings Holborn Circus in the City of London Watch Material Manu-
facturers, and EDWIN HODGSON LAW of Lupus Street Pimlico in the County of
Middlesex Watch-maker, do hereby declare the nature of this invention to be as
follows:-
This Invention has for its object to facilitate the springing of watch and clock
balances by providing a machine whereby the moment of inertia of a balance may be
accurately measured for the purpose of ascertaining the proper strength of the hair or
balance spring to be used therewith, and whereby the strength of hair or balance-
springs may be measured for the purpose of classification according to their different
degrees of strength. Heretofore, the mode of ascertaining the strength of spring
suited to a particular balance has been more or less conjectural and experimental, being
based on a mere comparison, either actual or mental, of the vibrations of the balance
to be sprung with the vibrations of a standard balance or pendulum, the operation
involving repeated trials with springs of different degrees of strength until one is
found which is suited to the balance to be sprung. This operation, besides being
troublesome and tedious, involving as it does the temporary attachment to the balance
of the different springs experimented with, is defective inasmuch as it is dependent on
the judgment and visual skill or training of the workman and the operation is further
complicated by the fact that the same balance would require to make a different number
of vibrations per hour, and would consequently require a spring of a different
strength according to which of the different kinds of watch train in vogue it is to be
used in.
The subject of this Invention is a machine whereby the moments of inertia of
balance and the strengths of hair springs may be ascertained with mechanical precision
and their values expressed according to any pre-arranged and corresponding scales or
codes, provision being made by reference tables or otherwis for the variations in the
correspondence between the two scales or codes to suit the different kinds of train with
which the balances and springs may be used,
'

page_text: By the use of this Invention nothing is left to the judgment of the operator except
the trial adjustment of the machine (after adding the balance or spring to be tested)
which is readily performed after little experience, the operation of the machine once
this adjustment is performed being purely mechanical and the accuracy of the
indication which it affords being entirely independent of the skill or judgment of the
operator.
The operation of the machine is based on the difference which the balance whose
moment of inertia or the spring whose strength is to be ascertained makes in the rate
of vibration of a standard balance when the balance or spring under observation is
carried by or attached to the standard balance and for the purpose of enabling this
difference to be ascertained mechanically two standard-balances timed to vibrate in
unison are combined and provided with means of attaching the balance or spring to
be tested, and with mechanism whereby their motion will be arrested when they do
not vibrate in synchronism, and with means of regulating their rate of vibration to
compensate for the disturbance caused by the addition of the balance or spring to be
tested whereby after a few trials the standard balances may be made to again vibrate
in practically absolute synchronism, the exact value of the compensation thus effected
and consequently the value of the moment of inertia, or the strength, to be ascertained
being indicated upon a suitable scale.
The following is a convenient arrangement of the machine but the Invention is not
limited to the particular construction described. The standard balances are mounted
side by side in jewelled holes in a suitable frame, and to the rim of one of them is
attached a movable arm which, so long as the balances vibrate synchronously, is unacted
on by the other wheel but which, when the synchronism of the two balances is disturbed,
is caused by the other wheel to engage in a catch whereby the motion of the balances
is arrested. The balances are provided with means whereby they may be set or turned
to equal angular distances and released at the same instant so as to vibrate in unison,
for which purpose the two balances are preferably made to temporarily engage with
one another, a detent engaging with one of the balances and thus holding both in the
set position and releasing them simultaneously, this detent being combined with the
catch above referred to in such manner that as the one is moved into, the other is
moved out of, operative position. One of the balances is provided with a table whereon
the balance to be tested may be placed in a central position so as not to disturb the
equilibrium of the balance, the staff of the balance to be tested entering a hole in the
centre of the table. The staff of one of the standard-balances is provided with a
conical head projecting beyond the jewel-bearing for the attachment of the balance
spring to be tested, the collet of the spring fitting tight on the conical head, and the
end of the outer coil being held by an adjustable clip. The springs of both balances
are provided with regulating indexes, movable over suitably graduated arcs whereby
the effective lengths of the springs may be regulated to compensate for the inertia of
the balance or the strength of the spring to be tested. The amount of compensation
necessary to restore the synchronism of the standard balances is easily ascertained
with the utmost accuracy after a few trials, and is the measure of the inertia or force
to be ascertained.

page_text: Clock Balances and the Strength of Balance Springs.
We GUSTAVE CORNIOLEY of the firm of Henri Picard et frère of 26 & 27 Bartlett's
Buildings Holborn Circus in the City of London Watch Material Manufacturers,
and EDWIN HODGSON LAW of Lupus Street Pimlico in the County of Middlesex
Watch Maker 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 has for its object to facilitate the "springing "of watch and clock
balances by providing a machine whereby the moment of inertia of a balance may be
accurately measured for the purpose of ascertaining the proper strength of the hair
or balance spring to be used therewith; and whereby the strength of hair or balance
springs may be measured for the purpose of classification according to their different
degrees of strength.
Heretofore, the mode of ascertaining the strength of spring suited to a particular
balance has been more or less conjectural and experimental being based on a mere
comparison, either actual or mental, of the vibrations of the balance to be sprung
with the vibrations of a standard balance or pendulum, the operation involving repeated
trials with springs of different degrees of strength until one is found which is suited
to the balance to be sprung. This operation besides being troublesome and tedious,
involving as it does the temporary attachment to the balance of the different springs
experimented with, is defective inasmuch as it is dependent on the judgment and visual
skill or training of the workman, and the operation is further complicated by the fact
that the same balance would require to make a different number of vibrations per
hour and would consequently require a spring of a different strength according as it
is to be used on one or other of the different kinds of watch train in vogue.
The subject of this Invention is a balance dynamometer whereby the moments of
inertia of balances, and the strengths of hair springs, may be ascertained with mechanical
precision and their values expressed according to any pre-arranged and corresponding
scales or codes, provision being made by reference tables or otherwise, for the variations
in the correspondence between the two scales or coles to suit the different kinds of
train with which the balances and springs may be used.
By the use of this balance dynamometer nothing is left to the judgment of the
operator except the trial adjustment of the machine (after placing the balance or spring
to be tested in position therein) which is readily performed after little experience, the
operation of the machine, once this adjustment is performed, being purely mechanical
and the accuracy of the indication which it affords being entirely independent of the
skill or judgment of the operator.
The operation of the machine is based on the difference which the balance or spring
(of which it is required to ascertain the moment of inertia, or the strength, as the case

page_text: may be) makes in the rate of vibration of a standard balance when the balance or
spring under observation is carried by or attached to the standard balance. For the
purpose of enabling this difference to be ascertained mechanically, two standard balances
timed to vibrate in unison are combined and are provided with mechanism whereby
their motion will be arrested when they do not vibrate in synchronism, and with means
of regulating their rate of vibration to compensate for the disturbance caused by the
addition of the balance or spring to be tested whereby after a few trials the standard
balances may be made to again vibrate in practically absolute synchronism, the exact
value of the compensation thus effected and consequently the value of the moment of
inertia or the strength to be ascertained being indicated upon a suitable scale.
Reference is to be had to the accompanying drawings forming part of this specifi-
cation and which illustrate a convenient arrangement of the machine, but it should be
understood that the Invention is not limited to the particular construction described.
Figure 1 is a front elevation, partly in section.
Figure 2 is a plan, partly in section, the standard balances being in the position
of rest.
Figure 3 is a similar view, the balances being "set" in readiness for testing a
balance.
Figure 4 is an end elevation.
The same letters of reference indicate the same paris in all the figures.
The two standard balances A B are mounted side by side in jewelled holes in a
suitable frame and are provided with balance springs whose effective length is regulated
by indexes C in the ordinary way, the indexes moving over suitably graduated ares D
on the base plate of the machine. The standard balances are intended to vibrate in
opposite directions and for this purpose their springs Care coiled in opposite directions
and the balances are provided with means whereby they may be set by being turned
in opposite directions through equal angular distances from their points of rest and
released at the same instant. If their regulating indexes D are at zero, the balances
will vibrate synchronously in opposite directions. To ensure their simultaneous release,
the two balances are preferably made to temporarily engage with one another by an
arm projecting from the rim of the one balance Bengaging a stud a standing up
from the rim of the other balance A whilst a detent E engages with a stud e projecting
downwards from the rim of the balance A. Both balances are thus held in the "set
position shewn in figure 3 so that when the detent E is withdrawn from engagement
with pine the two balances will be released simultaneously.
To the rim of one of the balances, B for example, is attached a movable arm F which,
so long as the balances vibrate synchronously, enters a notch G in the rim of the other
wheel and is therefore unacted on but which, when the synchronism of the two balances
is disturbed, comes in contact with the rim of the other wheel and is thereby caused to
engage in a catch H whereby the motion of the balances is arrested. The arm F is a
bell crank lever pivoted at one arm being pendent in position to vibrate in front of
the catch H whilst the other arm is acted on by a spring which holds the pendent
arm in a vertical position. The catch H is movable so that when setting the balances
it may be withdrawn out of the way as shewn in figure 3 but when in operative position
as in figure 2 it is close to the are described by the pendent limb of the arm F as the
balance vibrates. The detent E is carried by a spring so that the detent when in
operative position will yield and allow the pin e to pass in the act of setting the balance,
which is thus locked automatically. The balance A is first set and locked and the
balance B is then turned until the arm passes and engages with stud a as shewn
in figure 3. The catch H is carried by one arm of a bell crank lever pivoted at hon
the base plate and is moved outwards by a spring until it meets a stop ². The
detent E is fixed to a stud passing up through a slot in the base plate and carried by
a lever handle K pivoted to the underside of said plate whereby the detent is moved
towards or away from the balance A. The stad by which the detent is carried strikes
the other arm 3 of the hell crank lever, the detent and catch thus being so combined
that as the one is moved into, the other is moved out of operative position.
One of the balances, A for example, is provided with a table A¹ whereon the

page_text: balance a to be tested may be placed in a central position, so as not to disturb the
equilibrium of the balance, the staff of the balance to be tested passing through a hole
in the centre of the table and entering the lower hollow part of the staff of the standard
balance. The staff of this balance is made in two parts, the upper part being attached
to the balance by a bow A² connected to the rim of the balance so as to leave a clear
space upon the fable A' to receive the balance to be tested. The upper part of the
staff is also tubular and contains a sliding rod a which may be brought down
upon the staff of the balance to be tested in order to hold it in place on the
table A. The staff of the other standard balance turns at its upper end in a
jewel-hole without end stone, the journal of the staff being prolonged through the
jewel bearing and having a conical head L fixed on it for the attachment of the balance
spring to be tested, the collet of the spring fitting tight on the conical head and the
end of the outer coil being held by an adjustable balance spring holder M of the usual
kind mounted on the base plate.
If the balance to be tested he placed on the standard balance A and the balances A B
be started they will be at once arrested, but by moving the index of the balance. A the
effective length of its spring is altered so as to compensate for the inertia of the balance
under trial. The amount of compensation necessary to restore the synchronism of the
standard balances is easily ascertained with the utmost accuracy after a few trials and
is the measure of the inertia or force to be ascertained and similarly in the case of a
spring applied to the cone L of the other balance B.
Having now particularly described and ascertained the nature of the said Invention,
and in what manner the same is to be performed, we declare that what we claim is ;-
An instrument for ascertaining the moment of inertia of watch or clock balances
and for measuring the strength of balance springs, consisting in the combination of
two standard balances provided with mechanism whereby their motion will be auto-
matically arrested when they do not vibrate in unison, and with means of regulating
their rate of vibration to compensate for the inertia of the balance or the strength of
the spring under trial, one of the standard balances being so constructed as to carry
the balance under trial or to have attached to it the spring to be tested without
disturbance of its equilibrium, all substantially as herein described and illustrated in
the drawings annexed.
G. CORNIOLEY.
E. H. LAW.
By A. M. & Wm. Clark,
53, Chancery Lane, London,
Patent Agents.