IMPROVEMENTS IN CHRONOMETER MECHANISM, WITH COMPENSATION FOR MEAN AND EXTREME TEMPERATURE
Year: 1877

page_text: PROVISIONAL SPECIFICATION left by Peter Jensen at the Office of the
Commissioners of Patents on the 10th September 1877. (A communication
from abroad by August Ernst Müller, of Wolfsgraben, near Vienna, Austria.)
PETER JENSEN, of Chancery Lane, London.
"IMPROVEMENTS IN CHRONOMETER
MECHANISM, WITH COMPENSATION FOR MEAN AND EXTREME TEMPERATURE." (A
communication from abroad by August Ernst Müller, of Wolfsgraben, near Vienna,
Austria.)
The first part of this Invention refers to the wheelwork and the escapement
wheels.
The wheel teeth of brass or nickel alloy catch in the steel pinions of the arbors,
and the pivots of the arbors are running in brass holes or ruby stones. For the sake
of reducing the friction and wear of the steel, these parts of the wheelwork as
heretofore made must be oiled. There is no oil which does not condense and become
rancid, and then comes the dirt which forms itself by the wear of steel or brass, and
finally, the dust of the air in a shorter or longer time, in measure as the access of the
air to the wheelwork is less or more prevented by the cases. Thick oil, dirt, and
dust, form at last a sort of brown grease in the holes of the pivots and the teeth
of the pinion, which hinders the exact going of the watch, and finally stops it.
To avoid entirely the oiling the co-efficient of the friction is, according to this
Invention, reduced by the use of an antifriction metal, and by the application of new
escapements, which require less driving force, while the resistance of friction is
moderated proportionally with the reduction of the pressure.
According to this Invention the wheels are made of a silver alloy, the arbors with
pinions of steel, the pivots of the arbors of forged gold, which are put in the
drilled holes in the same manner as pivots of the cylinder, and these pivots go
in holes of stone. This construction of the running work has no need to be oiled.
Good polished pivots of forged gold of 18 carat going in stone holes do not wear,
they have the slightest friction, and do not become rusty, therefore they do not want
any oil.
The antifriction metal used for this purpose consists of metals mixed in or about
the following proportions :—45 ° of silver, 30% of copper, 9% of tin, 9% of

page_text: zinc, 7% of lead. This silver alloy is as hard as forged steel, and is still malleable,
and will take a good polish, it has an equally small friction co-efficient, as gold of
18 carat, and therefore requires no oil.
As the hard beaten plate of this silver alloy of which the wheels are made has
better qualities than the watchmaker's brass, the wheels can be made thinner, there-
fore they will be lighter, and their momentum of inertia smaller. Therefore the
diameter of the escapement wheels can be especially shortened, and the moment of
inertia of the escapement wheel of which the impulse must be surmounted can be
reduced to the half.
As the new chronometer escapements require less driving force than the chrono-
meter escapements used heretofore, as the resistance of friction at a reduced pressure
is proportionally moderated to it, and oil is not used, the movements constructed in
this manner are not only invariable as to power, but have also the greatest durability,
because the moment of inertia and friction resistances are very much reduced.
After each impulse of the balance the whole movement rests; at each fresh impulse
the inertia of all the wheels must be surmounted, and then begins the impulse.
Therefore there is only a loss of time, which is considerable with a weak driving
force and shorter with a strong one, but the friction resistance augmenting there is
wear, and one is forced to use the oil. This loss of time is variable according to
the temperature, because the gearing of the rim teeth into the pinion staves at
different temperatures is more or less deep by the extension or contraction of the
diameter of the wheels, the friction thus changing.
All these inconveniences are avoided by reducing the diameter of the wheels
as much as possible, and by using a perfectly elastic push at the impulse. There
is a great loss of force at the touching of un-elastic bodies; this loss is on the
contrary nil when an elastic body is touching another body in the same manner.
The hitherto used impulsion of the balance by the escapement wheel represents the
un-elastic push with parallel axles, as at the lever hammer and cam on the shaft,
which has a considerable loss of force.
The escapement wheel A, A, Figure I. and Figure II., the length of which depends
on those of the arbor of the pinion b, b¹, is so applied on the arbor of the pinion
that it is turning itself correctly and easily upon it. In the rim of the escapement
wheel the spiral roll c, c, is applied on the arbor of the pinion in the usual manner,
and on one of the 3 arms of the escapement wheel is fastened the small staff'd, Fig. 1.
Between both is the short spiral spring e, e, the ends of which are entering in the
holes of the spiral roll and of the staves, and fastened with screws f and f. In the
time in which the balance has made two oscillations, that is, in the sea chronometer,
in half a second, the balance or escapement wheel is quiet, and meanwhile the wheel-
work is able to strain the small spiral spring e, e. The disengaging of the escape-
ment wheel having taken place, the strained spiral e, e, has only to surmount the
inertia of the small and very light escapement wheel, therefore the division of the
impulse takes place without any loss of time, and with the whole strength of the
spring. The push of the tooth of the escapement wheel works here as the push of
an elastic body on an un-elastic one; it is the imperfect elastic push, because the
stone h which suffers the impulse is fastened in the plate g, g, Fig. IV. But the
push is perfectly elastic if the impulse stone h is fixed on the end of a spring
lever i, i, the spring of which lies close on the plate Fig. V. If now the push of the
tooth of the escapement wheel begins, the impulse stone on the spring lever slackens
as much as its spring allows it, and this spring transmits this acquired elasticity
without any loss of time to the balance. Using this construction one gains an equal
stretching of the spiral spring e, e, Fig. I, and therefore a push of even force, because
the movement has enough time to effect the stretching of the spiral e, e. As there
is no loss of force at perfect elastic impulses, a less driving force suffices, and the
friction is reduced proportionally on the pivot and the teeth of pinion. These are
new acquired qualities of great importance for the correct going of the watch, for
its durability, and the saving of the oil in the bearings and in the pinions.
The escapement wheel A, A, Fig. III., has teeth which are downwards, and is

page_text: fastened on the arbor b, b', and the pinion a, a, which forms with the spiral roll c, c,
a compact piece, which turns itself on the staff b, b', is carried by the short spiral
spring e, e. In order to preserve to this pinion its upright position, its teeth are
made to stand a little to the right, and it is then always pressed upwards by the
pressure of the tooth of the second wheel.
The escapement wheel A, A, Fig. XI, is made without the spiral spring because
the impulse is not effected by its teeth. Applying this escapement wheel to the
absolute constant impulse, the spiral spring is applied on the second wheel in order to
annul the expense of force for the surmounting of the inertia, exactly as described and
as shown at Fig. I. and II.
•
The material for this escapement wheel is the new invented silver alloy; it is pressed
out of a plate. The notches in the rim are made with wheel-cutting machine, and
then the escapement wheel is fastened on the arbor z, z, Fig. XII.
In the notches are put hardened pins of steel a, a, α₁, A₂, a ₁ az, and soldered
with care, in order that the pins do not lose their hardness. This arrangement is
also applicable to a cylinder escapement wheel of steel where there are no lifting
flats.
The next part of this Invention refers to the balance.
The correct going of a watch depends on the construction of the balance and of
its impulses with constant force. If there is to be obtained a correct going at each
temperature of the globe, namely, between the degree 40 to +60° C., then the
construction of the balance is of the highest importance.
-
If we consider the form of the balance used till this day, we perceive a number
of expansions and curves of the screw pieces (semi-rings) on which weights are
applied. At an elevation of temperature all these variations must work together
that the centre of gravity is equally distant from the centre, and this is an
impossibility.
The arms of the balance n, n, Fig. Xa, expand at the augmentation of the temper-
ature; with this the semi-rings m, m, and m¹, m³, are more distant from the centre,
the inertia is consequently increased. These semi-rings extend also in the
weights m, m¹, which are on them, are to be on one point distant from the end of
the arm a.
-
While the expansions and the contractions take place proportionally to the heat
degrees, the in curvates and the out curvates of the semicircles with the weights
must take place in singular progressive proportions + or of the proportional
expansions of the arms, and at last the modulus of elasticity of the cylinder
pendulum spring is again not to be brought in accordance with the compensation.
It is purely impossible between such a chaos of unequal expansions and contractions,
that is, at unequally variations of the centre of gravity, to make a watch or clock
which at middle or extreme temperatures go equally correct, especially if we consider
what accuracy there is required from a compensation, because a removal of the
centre of gravity of the weights induces at a balance of the sea chronometer a whole
difference from 30 - 36 seconds within 24 hours at 1/100 milimeter. We must
therefore give up entirely this compensation system, and search a new material for
new balance construction and compensation.
-
As the first principle may be named the following:-"The weights must always,
at mean temperature, in great cold and in great beat, stop in one and the same
distance from the centre of the balance; then the oscillations will also be equal at
each time, when the other parts of the balance do not occasion disturbances by a
removed position and by their own weight." This exigency is fulfilled to the
greatest extent if the weights rest on a base which does not extend itself if the
body of the base has only a slight specific gravity, and when the modulus of
elasticity of the cylinder pendulum spring is as slight as possible.
For the body of the balance on which the compensation arrangement are fixed is,
according to this Invention, used a plastic coal. This coal is produced of the
finest powdered coke of the best English coal, which is free from sulphur, iron, or
other mineral impurities, in the same manner as the carbon for electric light, and

page_text: for electric elements. The expansions of this preparation is at 100° C. only 0.00019'
and its specific gravity is 1·4, its hardness is a corresponding one as well as its
firmness.
By impregnation with amber varnish and gilding, each hygroscopic influence is
removed.
-
Instead of steel for the cylinder pendulum, springs is, according to this Invention,
used an alloy of platina with iridium melted, 80 90% of platina with 20 -10%
of iridium. According to the degree of hardness more or less iridium is used. This
alloy can be hammered; that which is more soft can be cast; it does not rust, and
takes a fine polish. Its expansion in length is the slightest, and its modulus of
elasticity is the least variable amongst all metals; it is per 1° C. = 0.0001.
The body of the balance for sea chronometer A, A, Fig. VII., VIII., is a disc of
the above-mentioned carbon. The two weights B, B', move, directed by lever arms
which are applied below b, b, c, c₁, at a distance from the centre of the balance, and
at the approaching to the same always directly in the line which is drawn from the
centre of the balance through the centre of the weights.
On the body of the balance are applied four fixed pins a and a¹, whereon turn
two armed levers b, b¹, and c, c¹, Fig. VII.; from the lever arms c, c¹¹, and b, 6¹¹, are
going the pins e and e₁, which are fixed on it, and on them are put gold weights B
and B₁.
The lever arms b, b₁, are each formed as a spring which rests on a set screw.
At the two other opposite lever arms c, c', screws d, d³, are put in against which repose
with half screw threads an upper and lower expansion staff or compensator q, q',
which has its rest point against the screw Q at the opposite end of the screw d, d.
The lever arms c, C, and b, b, Figure VIII., are equally long, the pins e and e
on it are likewise equal distant from the fixed pins a, a, in the balance body. The
weight R has two holes which are equally distant from the centre, and in which fit
the pins e and e¹.
If we turn back one of the set screws against the spring b¹, or if we turn back
the set screw Q, the expansion staff q, ql, is in both cases pressed on the screw d, d'.
By turning the screw the double armed lever c, c¹, is brought outwards, whereby
the corresponding lever arms c, C₁₁, is moved in the same time inwards with the
pin e, and consequently also the weight B which reposes on it. At this the other
lever arm b, b, is forced by its pin e' to turn likewise inwards, whereby the spring b¹
becomes a little more stretched; by the screws C we have the degree of stretching
entirely in our power.
The expansion staff q, q¹, is of steel or silver; the material is chosen for it
according to the effective modulus of elasticity of the cylinder pendulum spring.
By the turning of the screws d, d, the compensator can be approached to the lever
axle c or can be removed from it, whereby its expansion is transmissing itself more or
less to the movement of the weight.
The equilibrium of the balance is established by screws P, P₁, and they serve for
the regulation of the working.
The minor balance A, A, Figures IX. and X., is provided with a single compensation
arrangement. The expansion staff q, q', which can be turned is put in at q in a
fixed pin a on the body of the balance, and its pointed end q forms the support of
the lever arm b; its prolongation b, is a spring which is bent by the eccentric pin
head d. On the opposite lever arm is the weight B; this two-armed lever turns on
the pin g, Figure X. At the expansion the pole end 9 presses outwards the lever
arm b, and the corresponding lever arm c, c₁, with the weight B inwards. At the
contraction the bent spring b₁ pushes the lever arm c, c¹, up, with the weight B
outwards.
The regulation of the going, and the establishment of the equilibrium of the
balance take place by means of the 4 screws C, C₁, C, C,, at the periphery of the
balance.
The expansion of the balance body made of plastic carbon is not to be considered
because of the very slight degree in which it manifests itself, and the slight diameter

page_text: (12-15 millimeters and 20 – 25 milimeters) of the balances, because the specific
gravity of this coal is very slight. It is only the question about the modulus of
elasticity of the cylinder pendulum spring. If the same is of platina tridium, there
is only required a very slight compensation.
The next part of this Invention refers to the escapement:-For a good escapement
there is required,―
1. For the lifting of the lever and the disengaging there should be required the
slightest force of the balance.
2. The fall on the rest pin must follow certainly and quickly after each lifting,
and we must be able to correctly regulate the depth of the fall on the rest pin.
If the lifting and the disengaging has to follow with an expense of the slightest
force, then the lifting stone t, Figures IV., V., VI., must be approached as near as
possible to the balance staff, in order that its exterior edge has only one angle
velocity, and then the length of way required for the lifting and the disengaging
must be as short as possible; and at last that arrangement (the spring) which is
lifted by the lifting stone, not only have an absolute slight weight, but its length
and lever arm must be shortened as much as possible, because the moment of inertia
is increased in quadratic proportion with the length.
In the English lever escapement as well as in the swing bar escapement (bascule
echapement) one is forced to apply long springs and long lever arms, because the
rest stone m, Figures IV., V., instead of laying hold of the tooth a of the escapements
wheel tooth after its fall on the rest pin seizes only the following stone a¹.
According to this Invention the rest stone after its fall on the rest pin, seizes the
tooth a, the same one which has given the impulse, and the advantages acquired by
it are of great importance.
-
By this new invented construction of the spring they are shortened 2 3 times
compared with the swing bar escapement and the spring, and they are further 4- 6
times lighter, because the screw-lifting spring is done away with, and finally the
lifting stone t of the balance staff may be placed in the semi-distance of the centre,
whereby half of the angle velocity of the lifting stone is gained.
P
The moment of inertia is augmenting itself as the square of the length (= a) of
the lever arm or of the spring, according the formula T = /sa, and the force
which must be employed in order to bend or to turn the spring, or the spring bar
lever with the angle velocity wis w.
===
The above-mentioned fundamental formula shews the rapid diminution of force
at the prolongation of the lever arms or springs at an elevated angle velocity of the
lifting stone, and at the augmentation of the weight of the levers or the springs, and
this may be considered as the extraordinary advantage, and the great importance of
this Invention, admitting the use of shorter and lighter lever arms and springs and
half of the angle velocity of the lifting stone.
I will next describe the escapement for sea chronometers:-B, B, Figures IV.,
V., VI., is a two-armed lever which is fixed on the arbor 1, 1, Figure VI., in which
the two elliptic stones p and q are put in, and on which the locking or rest stone m
takes hold.
In order that this locking stone do not fall too deep before the tooth of the escape-
ment wheel there is at D the set screw r, with which can be correctly regulated the
depth of the fall on the rest pin.
The platina tridium spring C, C, is fastened at D; this latter part is made in the.
same manner as in other chronometer escapements, namely, moveable on the platina,
in order to be able to approach the spring of the lifting stone as it is required. The
spring is ground off in two places, the first one near D, in that degree that it is
strong enough to execute a sufficient pressure on the stone ellipse p of the lever B, B₁,
and the second above that ellipse p in order to get a sufficient flexibility of this part
of the spring which reaches the lifting stone t.
As the platina tridium spring C, C, is short and as this composition expands least
of all metals, the expansion of this spring is still to be considered as zero, even at

page_text: an extreme temperature, whereby one is able to considerably limit the fall of the
locking stone, because with short springs there are not vibrations in that measure
as at the long springs, and such vibrations cannot have any prejudicial influence on
the fall of the locking stone.
The posture of the spring must be in that manner that it presses just sufficiently
against the ellipse p, in order not to permit a recoil of the locking stone m at the
striking of the escapement wheel tooth, and that its top is reached by the lifting
stone, and sufficiently bent to the right. On the balance staff of the balance R, R,
is the flat disc g, g, Figures IV., V., VI., in which is encased the impulse stone h,
and the upright lifting stone t. Using the perfectly elastic impulse this disc is much
smaller, Figure V., and on the end of the spring i, i, which is close to the side of the
disc is encased the impulse stone h.
I will next describe the escapement with absolute constant force for watches and
clocks.
The lever B, B, is represented by the Figures XI., XII., XIV., XV.; it is made of
the silver alloy, and is fastened on the arbor b, b, Figure XII.
The arbor b, b, Figure XI., XII., has under the lever a half-moon curve; on the
two horns d and d₁, Figure XI., rest the two flat ground surfaces e, e, on the spring f, f,
Figures XI., XV., whereby the lever after each impulsion and each winding of the
impulsator is put in the resting situation, as shewn in Figure XV. If that lever is
made of steel, then in the spikes and c, and in the top c must be put stones in
the same manner as in the lever of the lever movement.
On the balance staff C, C, Figure XI., XII., of the balance is put in the small
disc D, D, with the spring cam E and the lifting stone F. The spring cam E
consists of the impulse stone m³, which is seized on the end of the spring 1, 1, and
this posture of the spring is close on the side of the disc at e, Figure XI. The
disc Figure XIII., XIV., XV., with fixed cam are for the imperfect elastic
impulses.
The impulsator Figure XI., XIII., XIV., consist of the balance staff g, g, and of
the lever arm / with the cam i, on which the spring h, k, presses. As this impulsator
is made of spring steel plate, there are put in stones on the end of the lever arm ₁,
and the cam i and the lever h are pointed with gold or silver alloy.
The cylinder pendulum spring can be spiral as in the usual watches; the cylinder
spiral spring has a safety movement, but they require a larger roam in height. With
the absolute constant impulse of the escapement is saved the necessity of regulating
the drawing force by fusees, and the use of isochronic cylinder pendulum spring.
It suffices perfectly if the cylinder pendulum spring is made in the same manner as
the usual steel ones, and these in the same manner as till now the spiral springs of
Brequet.