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By M. L. BOOTH, 





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Entered, according to Act of Congress, in the year 1860, by 


in the Clerk's Office of the District Court of the United States for the Southern 
District of New York. 


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Stereoiyper and Elecirotyper, 

CCai'ton iSuiDQinc[ t 

81, 83, and 85 Centre Street. 








Preface, ix 

Explanation of Plates, . xv 

Introduction, 1 

Watches, 4 

Balance Wheel or Verge and Crown Wheel, . • . . . 6 

Common Seconds Hand, ........ 14 

Breguet, 16 

Independent Seconds Hand, 24 

Repeating, 28 

Alarm, 36 

Clocks, 41 

Regulators, 42 

Ordinary Pendulum, 42 

Striking Hours and Quarters, 43 

Belfry, 48 

Pusee, the, . 53 

Barrel, the, . 62 

Stop works, the, j . 63 

Workmanship in General, .......... 65 

Gearings, 67 

Cycloid, the, . 68 

Epicycloid, the, 69 

Escapements, 74 

Balance Wheel, *75 

Cylinder or Horizontal, . . . . . . . .15 

Duplex, .80 

M. Pons de Paul, of; . 81 

Earnshaw's Detached, 267 

Hook, 82 

Spiral, 83 



Gearing, . . 83 

Inclined Plane, . .85 

Arnold, 86 

Pendulum and Belfry Clock, 90 

Graham, ........... 96 

Pin, 97 

Compensations in Watches with Circular Regulators, . . . .102 

Destigny, 105 

Perron, 105 

Robert, 107 

Pendulum Clocks, of, 108 

Other Methods of, 114 

Mercurial, . 117 

Leroi and Arnold — Chronometer Balances, 117 

Regulator of Portable Clocks, 125 

Pendulum, The, 135 

Theory of the, .... 136 

Regulator of Stationary Clocks, .143 

Problems for Determining the Number of Teeth to be given to "Wheels 

and Pinions, 146 

Curious and Useful Inventions, . . . . . . . .156 

Jurgensen's Method of Measuring Mean Temperature, . . . .200 

Hermetically Covering Mantel Clocks, 201 

Tools used in Clock and WatchmaKing, .204 

Annulled Patents, 229 

Cleaning and Repairing of Clocks and Watches, 261 

True and Mean Time, 262 

Regulation and Care of Clocks and Watches, 263 

Appendix, . 270 

Vocabulary, ... 281 


Among the mechanical arts, there is none more useful 
than that of horology, yet there are few less understood, or 
less practised in this country. Notwithstanding the great 
demand for time-pieces of various kinds, and the very 
general interest manifested in them by their owners, there 
are but few treatises on the subject in the English language, 
and those few too costly to be accessible to the million, 
while the most of the movements are imported from Europe 
instead of being manufactured by our own mechanics. But 
of late, more interest has been manifested, American clocks 
have won a world-wide reputation, and the manufacture of 
American watches has been attempted with a marked 
success, which augurs well for the future. It cannot be 
doubted that there is native ability enough among our 
artisans to execute superior workmanship ; the point in 
question is to afford it facilities for development equal to 
those enjoyed by other nations. 

The art of watchmaking requires as much theoretical as 
practical knowledge, and in Europe, where it has attained 
its greatest perfection, the workmen are instructed by 
numerous treatises, published under the supervision of 



distinguished mechanicians appointed by the government, 
which detail the mode of operation with scientific precision. 
These books are invaluable to the European artisans ; and 
such is the interest which they manifest in the subject that 
the most costly and elaborate treatises on the specialities 
of the art find a ready sale. The most of these are written 
in the French language — the universal language of the 
continent — and to them may be attributed much of the 
superior skill possessed by European artisans. 

The increasing interest manifested in the subject by our 
mechanics, together with the new impetus given to the trade 
by our manufacturing establishments, has led us, at the 
suggestion of a distinguished scientific man of this city, to 
compile a translation from the works before mentioned, for 
the use of American watchmakers. As the basis of our 
work we have selected M. Magnier's revised and enlarged 
edition of Le Norm and and Janvier's Manuel de VHorloger, 
recently published, and forming one of the volumes of the 
well-known Encyclopedic Roret — a condensed treatise on the 
art of horology which enjoys a high reputation in France. 
For the benefit of our numerous foreign workmen, we 
have endeavored to retain a literal translation of technical 
terms, so far as has been practicable without rendering the 
sense obscure to our native mechanics, adding a vocabulary 
of definitions of terms and synonyms of technicalities. 

The design has been to furnish to our artisans a com- 
prehensive treatise on watchmaking, which, without being 
confined to an elaborate description of a single speciality, 
should yet furnish details enough to be of real use to the 
workman as well as of interest to the amateur. The plan 


of the work, beginning with, a glance at the watches of 
Berthoud and Breguet, the principles of which still con- 
stitute the base of horological science, comprises descriptions 
and plates of the various gearings, escapements, and com- 
pensations in use among watchmakers, tools, patents, etc. ; 
together with instructions for cleaning and repairing watches 
and keeping them in order ; with such practical information 
as may render it useful to the general reader. Nothing has 
been adopted that has not been sanctioned by approved 
authority, and it is hoped that the present volume, without 
conflicting with other treatises, will prove a valuable addi- 
tion to our mechanical literature. 

The idea of the measurement of time dates back almost as 
far as Time itself; though its measure by mechanical means 
is of more modern origin, it is still so far distant as to be 
very uncertain. Four hundred years before the Christian 
era, Plato invented the clepsydra, the first clock of which 
we have any record, which marked the lapse of time by the 
falling of water, and indicated the hours by the sound of a 
flute. Since this time, the progress of watchmaking may be 
divided into nine distinct epochs, a sketch of which may not 
be out of place here. 

The first of these was marked by the invention of toothed 
wheels. But this must have been very ancient, for Ctesibius, 
who lived two hundred and fifty years B. c, used them in 
his clepsydra, and they were probably also employed in the 
moving sphere of Archimedes. 

In the second epoch, toothed-wheeled clocks were regu- 
lated by a balance whose alternate vibrations were produced 
by an escapement, and whose motive-power was a weight. 


This invention is attributed to Pacificus, who lived about 
the ninth century ; but it seems more probable that it was 
discovered in Germany, and that it only dates back to the 
thirteenth or fourteenth century. 

In the third epoch, which may be fixed at the close of the 
fifteenth century, balance-clocks were constructed which 
marked the seconds of time, and were designed for astro- 
nomical observations. These were used by Tycho Brahe, 
and also by Yaltherus. 

The fourth epoch presented the valuable invention of the 
spring formed by a band, which, bent in a spiral form and 
enclosed in a barrel, serves as the motive-power, and is a 
substitute for the weight; to this invention we owe the 
portable clocks, or watches, which were first made towards 
the middle of the sixteenth century. In this epoch, the 
striking-clocks, alarm-clocks, etc. were first constructed. 

The discovery of the pendulum by Galileo, about the 
commencement of the seventeenth century, marked the fifth 
epoch, which has become especially memorable by the 
application of this pendulum to the clock as a substitute for 
the balance. This application was first made by Huyghens 
towards the middle of the same century. 

The sixth epoch was marked by the application of the 
spring to the balance-regulator of watches ; by means of 
which this regulator acquires the property of making oscil- 
lations which are independent of the escapement, so that the 
elastic force of this spring is to the balance what the weight 
or gravity is to the pendulum. This successful application 
was made in 1660, by Dr. Hook. In 1674, the Abbe 
d'Hautefeuille made use of a straight spring, which Huy- 


ghens improved upon in 1675, by giving it a spiral form. 
Shortly after this time, the repeater was invented in Eng- 
land. It was first applied to clocks in 1676 by Mr. Barlow, 
and afterwards to watches by Messrs. Barlow, Tompion, and 

The seventh epoch may be dated at the close of the 
seventeenth century. Towards this period, considerable 
variations were perceived in the pendulum-clocks con- 
structed by Huyghens, and a new escapement, called the 
anchor, was substituted for the Huyghens escapement, which 
possessed the property of causing the pendulum to describe 
small isochronal arcs, thus rendering the ingenious inven- 
tion of the cycloid of Huyghens wholly useless. 

The eighth epoch was ushered in just before the middle 
of the eighteenth century, when a mechanism was adjusted 
to clocks which corrected the variations caused in them by 
the changes of temperature. At this epoch, the astronomical 
clocks had attained a high degree of perfection. 

The ninth epoch is that of the invention of chronometers, 
which seem to dispute its greatest advantages with the pen- 
dulum by a most valuable property discovered in the spiral- 
spring — that of rendering the unequal arcs described by 
the balance isochronal, or of equal duration. The execution 
of the different parts composing the clock has also been 
carried to a high degree of precision in this epoch, by the 
invention of various instruments and tools. The epoch of 
which we speak dates from the middle of the eighteenth 
century to the present time. 

Horology embraces within its province, first, public 
clocks, mantel clocks, and watches; second, astronomical 


clocks, and, thirdly, marine chronometers. We have en- 
deavored to give as clear and succinct descriptions of the 
principles on which these are constructed, together with the 
mechanical execution, as our limits will allow ; and we trust 
that these may enable our workmen not only to copy them, 
but also to apply them to new and superior mechanisms, 
and thus achieve a triumph for American manufactures. 
"We would tender, in conclusion, our cordial thanks to 
the many friends who have kindly aided us in the work ; 
especially to Henry Fitz, Esq., of New York city, to whom 
we are indebted for many valuable suggestions, and also 
for his revision of the proof-sheets of the present volume. 
Trusting that our work may sometimes prove a useful 
friend, we submit it to all who are interested in the subject 
of its commentary. 

New York. December 1, 1859. 



Fig. 1 and 2. — Berthoud's caliber for an improved balance-wheel 

Fig. 3. — Works of the same watch represented on a right line. 

Fig. 4. Description of the construction of the improved fusee-arbor- 

Fig. 5, 6, 7, 8, and 9. — Details of the parts of the fusee. 

Fig. 10 and 11. — Arrangement of the pieces of the balance-wheel 
watch, placed in the case in their true positions. 

Fig. 12 and 13. — Details of the potance and the pallet, with the steel 
plates, after the improvements of Berthoud, Sully, and Leroi. 

Fig. 14. — Description of the barrel-arbor with the curb of the 

Fig. 15. — Caliber of the Breguet and the demi-Breguet watches. 


Fig. 1. — Interior of the pillar-plate of a demi-Breguet watch, with 
all its wheels, bridges, and the balance. 

Fig. 2. — Exterior of the same pillar-plate, beneath the dial, the 
bridges and the slide for regulating the escapement. 

Fig. 3. — Construction of the demi- Breguet arbor. 

Fig. 4, 5, 6, 7, 8, and 9. — Breguet barrel-arbor and bridge with all 
the component pieces. 

Fig. 10. — Description of a repeating- watch with all the pieces of the 

Fig. 11. — Large repeating-hammer carrying the knob and pins. 


Fig. 12. — The knob of the hour-hammer seen separately. 

Fig. 13. — Canon pinion of a repeater with its quarter-snail and the 

Fig. 14 and 15. — Alarm watch with the two hands for the alarm- 

Fig. 16 and 17. — Regulator of Le Normand's machine for cogs. 


Fig. 1 and 2. — Pendulum-clock striking the quarters and repeating 
by the same train. 

Fig. 3. — Description of a new method for suppressing the fusee in 
watches without altering the equality of the force of the main-spring. 

Fig. 4, 5, and 6. — Different stop-works of the winding-up arbor for 
supplying the place of the chain-guard. 

Fig. 7, 8, 9, and 10. — Demonstration of the theory of the gearings. 

Fig. 11, 12, 13, 14, 15, and 16. — Demonstration and theory of the 
cylinder-escapement with the steel cylinder. 

Fig. 17. — Steel apparatus for supporting the jewel substituted for the 
steel cylinder. 

Fig. 18. — Form of the cylinder- wheel adopted by Breguet. 

Fig. 19, 20, and 21. — Mounting of the stone cylinder by Breguet. 
Figure 20 shows the form which he gives the pivots. 

Fig. 22. — Duplex escapement. 


Fig. 1, 2, 3, and 4. — Hork escapement of M. Pons de Paul. 

Fig. 5, 6, 7, and 8. — Spiral escapement of the same artist. 

Fig. 9, 10, 11, 12, and 13. — Gearing escapement of the same. 

Fig. 13, bis, 14, 15, and 16. — Inclined-plane escapement of the same. 

Fig. 17. — Arnold's detached escapement. 

Fig. 18, 19, 20, 21, and 22. — Detached escapement of Seb. Le Nor- 

Fig. 23, 24, and 25. — Different anchor escapements, two of which 
(Fig. 23 and 25) are dead beat, while Fig. 24 is recoiling. 

Fig. 26. — Lepaute's pin-escapement, for regulators and belfry-clocks. 

Fig. 27. — Breguet's compensation for watches. 

Fig. 28 and 29. — Destigny's compensation for clocks. 


Fig. 30 ana 31. — Seb. Le Normand's improvement upon the com- 
pensation of M. Destigny. 

Fig. 32 and 33. — Chronometer-balance of MM. Leroi and Arnold. 


Fig. 1.— Compensation for watches, by M. Perron, Jr. 

Fig. 2. — Compensation for watches, by M. Eobert. 

Fig. 3, 4, and 5. — Compensation for clocks, by M. Charles Zademach. 

Fig. 6. — Berthoud's instrument for regulating clocks. 

Fig. 7, 8, and 9. — Parts of the space-column tool of M. Eoger. 

Fig. 10. — Lever of Berthoud, for calculating the force of mainsprings 
of watches. 

Fig. 11. — Plane of the files for rounding cogs. 

Fig. 12. — Plane of the hand invented by Seb. Le Normand, ad- 
justed to ordinary machines for finishing cogs. 

Fig. 13. — Section of the same hand. 

Fig. 14. — Wheel-click-pin placed on the sides of the machine for 
finishing cogs, and designed to change the backward and forward 
movement of the hand to an alternate circular movement. 

Fig. 15. — Geometrical demonstration of the causes which necessitate 
a progressive movement of the slide which carries the rack, E, P, ac- 
cording as the rounding file encircles one or several teeth in its action. 

Fig. 16. — Forms of the teeth of the wheeL 

Fig. 17 and 18. — Elevation and plane of the space-column tool. 

Fig. 19, 20, and 25. — Elevation and plane of the inclined-plane tool. 


Fig. 1 and 2. — Profile of a lathe-rest for rounding pinions. 

Fig. 3. — New lathe for the pivots. 

Fig. 4, 5, and 6. — Elevation, plane, and detail of a new pivot-compass. 

Fig. 7 and 8. — Plan and separate piece on a larger scale of an in- 
strument for cylindrical turning. 

Fig. 9, 10, 11, 12, and 13. — Tool for inclining the teeth of cylinder- 
wheels equally, represented in five different positions. 

Fig. 14, 15, and 16. — Tool for equalizing the teeth of cylinder- wheels 
and forming the inclination of the back of the tooth. 

Fig. 17, 18, and 19. — Tool for polishing the columns of the cylinder- 






The art of Horology, or of measuring time by clocks 
and watches, unquestionably ranks among the most won- 
derful productions of the mechanical arts. Through the 
improvements made in it during the last century, it has 
now reached so high a degree of perfection, that it is safe to 
believe that it will not advance much further, either in the 
construction and perfect execution of the different parts of 
time-pieces, or in the invention of tools designed to abridge 
the labor and to ensure perfect accuracy and regularity of 
movement. We shall therefore render an important service 
to intelligent workmen who are anxious to avail themselves 
of all the modern improvements, by offering to their notice 
a description of the methods employed by the best artisans 
in the manufacture of their clocks and watches. 



Oar plan more particularly embraces a description of 
the workmanship executed in Paris, which is j ustly thought 
to excel that of the Swiss manufacturers. We shall enter 
into the details necessary to the exact description of all the 
manipulations employed by the most celebrated watch- 
makers, show the improvements which have been introduced 
in the manufacture of watches, mantel and belfry clocks, 
and chronometers, and describe the various tools which 
have recently been invented both for abridging the mani- 
pulations and rendering them more exact. We shall give 
valuable instructions in respect to repairing and regulating 
clocks and watches, and keeping them in order when they 
are thus regulated. These are very important, for excellent 
watches are often spoiled by inexperienced workmen to 
whom they are entrusted for repairs, or greatly injured by 
a want of care or knowledge on the part of their owners. 
We have endeavored to remedy this, by giving full and 
minute directions as to the care and management of time- 
pieces, which cannot fail to be valuable to all who own 
them. We have also described the various escapements 
now in use, together with the most important gearings, and 
several useful tools which have lately been invented. 

The Manual is divided into chapters, in which we shall 
treat successively : first, of the manufacture of watches ; 
second, of apartment clocks ; and third, of belfry clocks ; 
and in these we shall avoid describing any workmanship 
which is not approved by the best artisans. 

Machines for Measuring Time. 

The general name of " clock " is given to any machine 
that divides time into equal parts and indicates these 
divisions. Clocks are made of different sizes, to adapt 
them to the various demands, and are distinguished by 


names suggestive of their uses. These are, first, portable 
clocks, or watches; second, stationary clocks, which are 
used in apartments; and third, belfry-clocks, intended for 
public uses. Besides these are the marine chronometers, a 
chapter on which will be found in the volume. 

The mechanism of a clock, to whatever use it may be 
applied, is composed of several essential parts, which, by 
their correspondence, secure an exact measurement of time. 
These are : first, the regulator ; second, the escapement , 
third, the train ; fourth, the motive power ; fifth, the click- 
and-spring work, or means of winding up the motive 
power ; and sixth, the dial and hands which mark the time 
measured by the clock. 

The regulator is a most important feature of the me- 
chanism, and is the true instrument of the measure of 
time, dividing it, as it does, by its quick and regular move 
ments. By aid of the escapement, to which it is joined, 
it regulates the velocity of the wheels, whose functions are, 
in turn, to mark the movements of the regulator ; and, 
by a double effect of the escapement, these same wheels, 
by their action upon it, transmit to the regulator the force 
of the motive power, so as to sustain the vibratory move- 
ment which the friction and the resistance of the air tend 
to destroy. 



The watchmaking of the present day may be divided 
into two distinct systems, the more ancient of which is 
distinguished by two pillar-plates, which are separated by 
four pillars of equal length, and between which are placed 
the wheels and other parts of the mechanism. This system 
was greatly improved by Ferdinand Berthoud. The de- 
tails of his improvements will be found in the following 

The second system belongs to the well known Breguet, 
who has suppressed one of the pillar plates, and conse- 
quently the pillars forming the frame, besides making 
various other simplifications which will be noticed hereafter. 
We shall speak first of the common watches, and afterwards 
describe the improvements which Breguet has introduced 
into the pocket repeaters. 


The improvements introduced by this skilful artisan 
into the construction of balance-wheel watches were the 
fruits of constant observations, guided by a long-conti- 
nued and profound study of the mechanical sciences. Yet 
no authority can be considered final ; and while we ac- 
knowledge his profound science and the general excellence 


of his system, we shall proceed, in our description of it, to 
point out the farther improvements which have been 
suggested by later experience. 

He preferred the verge to the dead-beat escapement, 
because this escapement gives a great . movement to the 
balance-wheel, while a very small space in the escapement 
is passed over, and but a slight friction is obtained. In 
this we must differ from him ; for we can easily prove, 
both from long experience and daily use, that the balance- 
wheel or verge escapement, although more easily made by 
ordinary workmen, has not the accuracy of the dead-beat 
escapement, that its recoil can never be entirely obviated, 
and that this cause, in itself, is sufficient to deprive it of the 
regularity essential to this part of the watch; and that 
the many attempts which have been made to render this 
escapement isochronal have all proved futile. But we 
shall speak further on this subject in our chapter on 

Berth oud seems to attribute the wearing of the pallets 
solely to the communication of the thick oil to this part of 
the escapement, without taking the quality of the brass em- 
ployed in the wheels at all into account ; yet no observing 
eye can have failed to perceive that this is the principal 
cause, and that if the wheels are made of good brass, the 
friction will have little or no effect on them. 

Yet the verge or balance-wheel watches should not be 
utterly proscribed for several reasons. In the first place, 
they are more easily made and repaired by ordinary work- 
men ; secondly, they are of a much lower price, and con- 
sequently within the reach of those who do not care for 
extreme accuracy in a watch ; and thirdly, they do not 
require as frequent attention as watches with dead-beat 
escapements, which need fresh oil often. For the balance- 
wheel watches as improved by Berthoud, see Plate I. 


Common Balance-wheel Watches. 

Figures 1 and 2 represent the caliber. To trace this, take 
a piece of brass, a line in thickness and a little smaller 
than is required for the caliber, forge this carefully until 
it is reduced to one-half its original thickness, and is about 
nineteen lines in breadth. After smoothing both surfaces 
with the file, and after removing all the strokes of the 
rough file with the smooth one, pierce a small hole in the 
middle, exactly perpendicular to the surface of the plate, 
with a spring compass; trace the circle of a radius of 9-J 
lines, then fix it with sealing-wax upon an arbor, taking care 
to place it as truly as possible upon the lathe ; this can 
easily be done by heating the caliber by means of a blow- 
pipe and the flame of a candle. Then profit by the heat 
imparted to the brass plate to adjust it properly, by lightly 
pressing against its surface a piece of wood, held firmly on 
the rest of the lathe, while the mandrel is turned by the 
drill-bow. It is then left to cool in its place, still turning 
the drill-bow. When the caliber is quite cold, it may be 
turned on its edge to reduce the circle to nineteen lines in 
diameter, which is the dimension required for the large 
pillar-plate. Care must be taken that the outline of this 
circle be cylindrical instead of conical. Then, with the 
burin, give to both surfaces, and the edge, strokes extend- 
ing across them, or rather, somewhat bevelling ; remove 
the plate from the mandrel and warm it slightly with the 
blow-pipe ; and finally, file off both surfaces upon a cork 
cylinder, so as to level down the strokes which have been 
given it, without removing them entirely, even of the 
smooth file, these are afterwards effaced with water-stone. 
An equal thickness is thus given to the plate. 

It now only remains to trace the position and dimensions 


of tlie wheels and necessary pieces upon the two surfaces. 
A great degree of skill is required to do this from memory, 
and artisans generally copy the best executed works in 
their possession. 

Upon one of the surfaces of the caliber trace all the 
pieces belonging to the interior of the watch, and those 
which are to be placed on the small pillar-plate; and upon 
the other surface, those which belong beneath the dial. 
The centre of all the wheels, as well as of the balance, 
should be pierced with small holes, perpendicular to the 
surface of the pillar-plate. In our description of the man- 
ner of copying a caliber, we shall also show the method of 
marking it. 

Figures 1 and 2, PL I., represent the two surfaces of the 
caliber. Figure 1 shows the interior of the frame and the 
upper part of the small pillar-plate ; Figure 2 shows the 
arrangement of the pieces which are placed on the large 
pillar-plate beneath the dial. 

Place the caliber to be copied upon the plate which has 
been already prepared, placing the holes which are in the 
centre of each together, and carefully passing a copper pin 
through both in order to secure them from any change of 
position, then press the two plates together with pincers, 
first wrapping a scrap of paper about the pieces so that the 
pincers may not injure them. Care should be taken to 
place the blades of the pincers in such a position that they 
will not cover any of the holes that are to be pierced. 

Having pierced the holes with a small drill, and separated 
the plates, trace the circles with the utmost care. For this 
use the burin or watchmaker's compass, holding the points 
exactly perpendicular to the surface to be traced. 

The barrel, a, is placed at the side of the fusee, b ; the 
spring is better so because it is larger, and the barrel being 
higher, it is less apt to vibrate on its axis. 


The large centre- wheel, c, is at the centre ; the small 
centre-wheel, d, and the crown-wheel, f, are traced after- 
wards. From the centre of the balance, g, to the centre of 
the crown-wheel, f, the straight line, % is drawn, which in- 
dicates the position of the pinion of the balance-wheel. 
From the same centre of the balance, g, the straight line, 
t A, is drawn, perpendicular to the line, if. This line, i h, 
represents the front of the potance, which should occupy 
the whole space between this line and the barrel, with a 
slight play for the passage of the chain. This is all that 
belongs to the interior of the frame. 

The other pieces traced upon the caliber are — first, the 
bridge of the fusee, m; second, the rack groove, n; and 
third, the rosette, o. 

The other surface (Fig. 2) shows the pieces which are 
under the dial; first, the canon-pinion that carries the 
minute-hand, p ; second, the minute-wheel, g, with its 
bridge ; third, the dial-wheel, r ; fourth, the bridge, s, 
which receives the pivots of the small centre- wheel and the 
crown-wheel ; fifth, the ratchet-wheel of the barrel, £, which 
serves to confine the mainspring, and to secure it by the 
click, v ; sixth, the holes 1, 2, 3, 4, which mark the rests 
of the pillars. 

Before describing the manipulations which should be 
employed in the execution of all the pieces composing this 
watch, it is important that we show the advantages pos- 
sessed by this caliber. From Figure 3, in which Berthoud 
has placed all the parts on the same right line, and the 
pillar-plates of which are intersected by the centre of the 
holes, we may easily do this. 

The large pillar-plate, or plate of the pillars A A, is made 
from thick brass. Around it is arranged a beater or false- 
plate, a a, and a groove and fillet, b b, so that it may rest 
on the edge of the case. In the centre, at the side of 


the beater, the large drop, c c, is placed, the use of which 
we shall presently learn. This pillar -plate should be 
about one line in thickness, the smaller one is somewhat 

A cavity with a flat bottom is then made by means of 
the lathe in the centre of the large pillar-plate, to contain 
the entire thickness of the centre wheel, B, leaving a small 
space so that it may not rub against the cavity in the plate. 
The drop, c c, of which we have spoken, holds the base of 
the rod of the centre-wheel, to which a short rod is left, 
designed to carry off from the wheel and centre pinion, the 
oil which is placed in a reservoir made in this drop on the 
side of the dial. 

The centre-wheel, B, thus resting in the body of the 
plate, facilitates the support of the fusee, C, with its wheel, 
and thus gives greater solidity to the chain. The barrel, D, 
which is placed at the side of the great wheel, also reaches 
to the top of the frame, and a spring is thus obtained 
whose spring-band is broader, and consequently, stronger 
and more solid, although thinner. 

To obtain for the fusee, C, the advantage of the drop in 
the centre-wheel, namely, that of carrying off the oil from 
the base, M. Berthoud proposes to place a drop, d, at the 
opening of the fusee-hole in the large pillar-plate, with a 
cavity resembling that of the centre- wheel. To obtain a 
similar drain from the upper pivot, he places a strong- 
bridge, f, upon the small pillar-plate which receives the 
pivot ; this bridge is fastened with a screw. 

By the aid of the bridge, h, which the author has placed 
under the dial, giving it as much elevation as the position 
will permit, he has facilitated an increased length of the lower 
rods of the small centre-wheel, E, and the crown-wheel, F, 
and by placing the plane of the small centre- wheel between 
those of the large centre and the crown wheel, he has 



resolved an important problem of mechanism. He thus 
arranges these three wheels in such a manner that the pres- 
sure which each exerts upon its respective pinion is nearly 
at the centre of the length of the rods between the two 
pivots. By this method, the friction is equally distributed 
between these two pivots. 

Before this happy arrangement was made, the small 
centre-wheel was sunk in the large pillar-plate, its lower 
pivot being carried with scarcely any rod in a cap which 
crossed the cavity ; and the large centre- wheel was placed 
upon the large pillar-plate with no grooving ; this lessened 
the base for the fusee and barrel. The pinions of the large 
and small centre-wheels were rarely sheltered from the oil 
which their leaves contained. This was also the case with 
the wheel q (Fig. 2) which, rubbing against the large pil- 
lar-plate, often took the oil placed upon the large centre 
wheel and accelerated the friction of the machine. 

In the new construction (Fig. 3) the pin that holds the 
minute-handle, g, being elevated on account of the drop 
c, c, thus causes the like elevation of the wheel, */ the 
pinion of this has a longer rod whose pivot turns in the 
pillar-plate, its other pivot entering the bridge, C. 

By placing the rod, m. of the balance-wheel perpendicular 
to the rod of the wheel F, a double advantage is gained, as 
we thus obtain a shorter and more easily turned rod, and a 
more perfect gearing than whea this rod passes by the side 
of the rod of the crown-wheel and ends at the edge of the 
small pillar-plate. 

The author has also improved the two pieces in which the 
two pivots of the ba'ance-verge move. The lower pivot 
moves, as before, in the arm of the potance, and its point 
rests on a plate of tempered and polished steel. A small 
plate is placed upon the lower foot to carry off the oil. Above 
the cock is placed a balance-cock of brass which should 


be as thick as the case will permit, as may be seen in P, 
and npc-n this is another balance-cock of tempered and 
polished steel. These two balance-cocks are fastened to- 
gether by the same screw, the brass balance-cock being 
more firmly secured to the cock by two chicks which pre- 
vent it from turning. In order to turn the oil towards the 
two pivots, the arm of the potance and the brass balance- 
cock are rounded by a screw with a round head, on the 
side of the steel plates, care being taken to leave a small 
space between this screw and the steel plate to permit the 
passage of the oil. In this manner the oil is drawn towards 
the end of the pivots without extravasation. We shall pre- 
sently speak of the potance. 

In the old construction, the upper pivot turned in the 
cock, and the verge had no plate ; the oil therefore was soon 
dried up by spreading over the whole surface of the balance- 
cock. In the new arrangement, a long rod is given, as may 
be seen in ^>, which often preserves this pivot from break- 
ing ; care should be taken to have the aperture of the cock 
as small as possible, without letting the rod rub against its 
interior. This construction also possesses another advan- 
tage, — that of preserving the balance-wheel from injury — 
since, if the aperture of the cock is small enough, it holds 
the verge in its place, and the train cannot move if the 
upper pivot is broken by a fall. 

We shall not speak here of the construction of wheels or 
pinions, nor of the barrel and escapement, as we have 
devoted several chapters, in another part of the book, to this 
important subject. We shall limit ourselves now to the 
description of the fusee, as invented by Ferdinand Berthoud. 

Figure 4 represents the fusee-arbor in profile and per- 
spective. This arbor is made of steel, and is forged from a 
single piece. The arbor is commonly soldered to the fusee 
with tin, but the method is defective, as these fusees are apt 


to break away. The following arrangement is preferable, 
and also possesses the advantage of permitting the fusee to 
be renewed without difficulty, yet preserving the arbor. 
After having turned the rod a, to its proper dimension, it is 
fitted closely in the hole in the centre of the fusee B (Fig. 5), 
which represents the top of the fusee ; a cavity is then made 
in the upper part of the fusee, into which the body of the hook 
is sunk, while the hook itself enters the notch b. The arbor 
is joined to the fusee by means of a screw, so that it cannot 
turn separately ; this screw confines the arbor to the cavity. 

The click and spring-work is lodged in the base of the 
fusee to give it the greatest possible size ; for this the base 
C C (Fig. 6), seen from beneath, is grooved with two inden- 
tations; in the first, a a, rests the click-spring and the 
ratchet-wheel, carried by the great wheel, D D (Fig. 7); in 
the second, b b, is closely fitted the flange, c c, of the cog- 
wheel B, seen flat and raised (Fig. 8). The teeth of the 
cog-wheel are placed on the first grooving, a a (Fig. 6). 
This cog-wheel, seen in profile (Fig. 8), has two pins, 1, 2, 
which enter the holes b b (Fig. 6). Thus, the cog-wheel is 
impelled by the fusee, and rests upon the bottom of its 
grooving, being held there by the great wheel. This wheel, 
D D, is held against the base of the fusee by a piece of steel, 
F (Fig. 9), which is termed a drop. This piece rests in a 
funnel-shaped cavity, sunk in the centre of the great wheel ; 
it is for this that the drop, d d, is reserved, resting in the 
space in the cog-wheel E (Fig. 8). The piece t" tj / (Fig. 7) 
is the click-spring, which is riveted on the wheel with brass 
pins ; g is the click. 

Figures 10 and 11 show the arrangement of the different 
pieces of this watch in the interior of the frame. Fig. 10 
shows all the pieces without the pillar-plate, which is re- 
presented reversed, that is as seen from beneath when it 
covers the large plate. The same letters indicate the same 


pieces seen in Fig. 3, but arranged in the order in which 
the j are placed in the watch. 

In Figure 10, we see in B the head of the regulating-plate 
with the hinge S, the crown-wheel, consequently, is placed 
on the diameter indicated on the dial by the figures 12-6, 
being placed above the figure 6. 

In Figure 11, we see the potance, H, which we shall here- 
after describe; the balance-wheel, Gr, whose inner pivot 
enters the pallet; the counter-potance, n, with the screw 
that fastens it to the pillar-plate, and the steel plate against 
which its outer pivot revolves. "We also see the chain- 
guard, r, with its spring, s; the outline of the barrel, 
the chain and hook of the fusee, dotted and representing the 
momentum of the stop-work of the fusee. 

We shall now give the number of teeth of wheels and 
leaves of pinions, which Berthoud has prescribed for watches. 

Common Watches. 

Teeth of 

Leaves of 




per hour. 

Great wheel 


Large centre-wheel 


""- — -12 . 


Small centre-wheel 


""~- 6 . 

. 10 



~^— -6 . 

. 80 

Balance-wheel ~. 


~~^— 6 . 

. 600 

The inclined lines which connect the figures in the pre- 
ceding and following examples, indicate the pinions into 
which the corresponding wheels work, thus causing their 

The balance-wheel, as we see here, makes six hundred 
revolutions per hour, while the large centre-wheel makes 
but one in the same time. But as the balance-wheel has 
thirteen teeth, and as each tooth produces two vibrations, 
by multiplying six hundred by twenty-six, or twice thirteen, 



we obtain for a product 15,600, which is the number of 
vibrations which the balance beats in an hour. Experience 
has proved that a watch which beats from 17,300 to 17,400 
vibrations goes with the most regularity, and is the most 
easily regulated. This rule is now practised. 

Common Second- Watches. 

Berthoud, in the arrangement of his caliber, intended to 
suit it either to common or second-watches as he declares, 
and as may be seen from the caliber, Fig. 1, and the dispo- 
sition of the pieces, Fig. 10. We see in the caliber the dia- 
meter, r, 5, which indicates the line of the hours 12 and 6 ; 
12 at r, and 6 at s. In this construction it is only necessary 
to change the number of the teeth of the wheels and the 
leaves of the pinions thus : 

Teeth of 

Leaves of 




per hour. 

Great wheel 


Large centre-wheel 


^^12 . 


Small centre-wheel 


~~^-^8 . 



48-, r 

~"~^- — 6 . 

. 60 

Balance-wheel . 


^^—5 . 

. 480£ 

The balance-wheel has fifteen teeth, thus giving thirty 
vibrations to the balance in each revolution, and conse- 
quently 14,400 vibrations per hour, or four per second. By 
lengthening the pivot of the crown-wheel which makes 
sixty revolutions per hour, or one per minute, and placing 
a slender hand upon this pivot, this needle will mark the 
seconds, divided into fourths, upon a small dial traced above 
the figure 6. The fifty-four teeth of the great wheel, as 
recommended by Berthoud, work into a pinion of twelve, 
and necessitate six and a half turns of the spiral-spring 
around the fusee for the watch to run thirty hours without 


winding, as is the general custom. This arrangement has 
not been sanctioned by most clock-makers ; they give sixty 
teeth to the great wheel and ten leaves to the pinion of the 
large centre- wheel. This combination, which does not 
change the caliber, gives but five turns round the fusee, 
while the watch runs thirty hours. 

The description of new watches which we shall give, after 
describing the potance invented by Berthoud, will be suf- 
ficient to show the manipulations employed by good work- 
men in the execution of these ingenious machines. 

The Potance. — We owe to Ferdinand Berthoud the per- 
fection of this piece, which is important on account of its 
function of receiving the three principal pivots of the 
escapement. He gives the following description. 

" The potance, C, is seen in profile in Fig. 12 ; d d is the 
grooving made to receive the pallet or potance D (Fig. 13). 
The adjusting-screw, e, enters into the hole tapped in the 
potance parallel to the course of the pallet. The part g of 
this screw enters into the notch h of the pallet D (Fig. 13). 
This, therefore, is only moved in the grooving of the po- 
tance as the adjusting-screw is turned. This movement of 
the potance is necessary in order properly to adjust the 
watch in its beat. To confine the pallet to the grooving, 
d d, of the potance, the latter is perforated at k, and a 
screw inserted whose head rests on the pallet, and the hole 
ft, through which the screw passes, is lengthened to prevent 
it from checking the movement of the pallet. The plate E 
is of steel, it is fastened by a screw to the top of the po- 
tance to receive the end of the pivot of the balance- verge 
which revolves in the arm, f, of the potance. This arm is 
rounded off on the top with a round-headed screw to retain 
the oil of the pivot between the spherical part and the plate 
E. The chicks 1, 2 of the potance fit closely into the holes 
of the small pillar-plate. To prevent the oil which is put on 


the inner pivot of the balance-wheel from being carried 
past the pallet, Leroi has conceived the idea of covering 
this hole with the steel plate F (Fig. 13), which meets the 
pallet and is secured to it by the screw which fastens it. 
The end of the pivot of the balance-wheel revolves on this 
plate. To secure the simultaneous movement of the steel 
pallet and the nose of the potance, the latter bears the pin 
n, which enters a hole in the steel plate. 

"The potance, m, is rounded off at the back by a round- 
headed screw in order to retain the oil of this pivot. We 
see in Gr (Fig. 13) the steel plate joined to the pallet. The 
credit of this excellent method of confining the oil to the 
pivots is due to Messrs. Sully and Leroi." 


The Breguet system of watches differs essentially from 
those we have just described, first, in the caliber, and 
second, because the large pillar-plate, without pillars, alone 
is used, the small pillar-plate being replaced by bridges. 
The fusee movement is not employed, and the escapement 
is usually a cylinder of Breguet's own invention. 

The watches called demi-Breguet are constructed on 
the same caliber, the only difference being in the form of 
the bridge which supports the barrel. We shall first 
describe the demi-Breguet watch, and afterwards speak of 
the bridge which we have just mentioned. 

Figure 15, PI. 1, shows the caliber in its natural size. 
We see at A the barrel, which has eighty teeth ; at B, the 
large centre- wheel, with sixty -four teeth and a pinion of ten 
leaves; the small centre- wheel, 0, has sixty teeth, with 
a pinion of eight leaves ; the crown-wheel, D, also has sixty 
teeth, and its pinion eight leaves; the cylinder-wheel, E, 


has fifteen teeth, with a pinion of six leaves. "We see at 
F the dimension of the balance. It may easily be seen that 
this watch beats 18,000 strokes in an hour. 

Figure 1, PI. 2, shows this system on a larger scale than 
the caliber (Fig. 15, PL 1), in order to point but more clearly 
all the parts of the watch. The movement here is seen 
upon the surface of the pillar-plate, opposite the dial, 
because, as we have already said, there is but one pillar- 
plate in this kind of watch. The pillar-plate, A, has a 
small base around its edge by which it rests on the case, 
to which it is fastened by several screw-keys. 

The barrel B, of which we see but a part, the rest 
being hidden by the bridge C C, carries eighty teeth on its 
rim. The bridge C C, is fastened upon the pillar-plate, A, 
by two strong screws, a a, and two chicks. We see on 
this bridge a steel ratchet-wheel, b ; a click- wheel, c, and 
moving upon a screw, is constantly impelled against 
the teeth of the rachet-wheel by the spring, d, which is 
fastened to the bridge by a screw and chick. These 
two last pieces are also of steel. The three screws which 
we see on the ratchet-wheel around the centre, are not 
tapped into the bridge, as might be supposed from an 
inspection of the plate, but are screwed into the base of the 
arbor, for otherwise they could not turn; they serve to 
join it to the barrel-arbor, which winds the main-spring and 
holds it by the click and spring- work, so that it may not 
fall back. It is in the adjustment of the pieces which 
compose the barrel-arbor, the click and spring-work, and 
the form of the bridge, C C, that the Breguet watches differ 
from the demi- Breguet, of which we are now speaking ; we 
shall hereafter describe the difference of these pieces, and 
compare them in order to point out this difference. ■ 

The large centre- wheel, D, is the highest of all, passing 
above the barrel and the balance, as may be seen in the 


plate ; this is supported by the bridge, E, which is fastened 
to the pillar-plate, like all the others, by a strong screw 
and three chicks. 

The small centre-wheel, F, supported by the bridge, G, 
is placed under the large centre-wheel, D, and beneath 
the balance. 

The fourth wheel, H, is supported on this side by the bridge, 
I. This cylinder- wheel passes through the pillar-plate into 
an opening which we see in Fig. 2, at M, and is lodged in a 
cavity made in the barret K, which is fixed upon this sur- 
face of the pillar-plate by two good screws and two chicks. 

The cylinder-wheel, which is concealed in the figure 
by the bridge, K, which supports it, and by the balance, 
has one pivot revolving in the bridge, K ; the other revolves 
in the barret, N, which is found on the other surface of 
the pillar-plate, and which also receives the lower pivots 
of the two wheels, F and H. 

The upper pivot of the balance revolves in the cock, L ; 
the lower pivot moves in another bridge, which is placed 
on the other surface of the pillar-plate, and is called the 
chariot. The bridge, L, of which we have just spoken, sup- 
ports the small ear, r, which receives beneath, in a small 
hole which may be seen there, the pivot of the pinning of 
the spiral spring. We see a sort of hand at m ; this is the 
end of the regulator, which is moved to the right or left to 
accelerate or retard the movement of the watch. This pieec 
is made in the following manner. Take a thin piece of steel, 
long enough to reach from the end of the hand, m, to its 
opposite extremity, o, pierce a hole in the centre of the part 
n, place it on an arbor, and trace the two circular lines seen 
in the figure. The centre of the circle may even be 
removed, care being taken to make the hole slightly coni- 
cal; that is, smaller on the surface designed to rest on the 
cock, L, than on the outer part. The rest is filed to the 


shape indicated in the figure. Then place on the circle 
the small piece of steel, w, which is inversely conical to the 
hole in the regulator. This piece is fastened to the cock 
in the middle of the regulator by two screws. The regu- 
lator can now be turned with ease around the piece, n, 
grazing it slightly. 

The ear, o, at the end of the regulator, has two small pins 
on the under side, very near each other. Between these 
two pins passes the first turn of the spiral-spring, the elas- 
ticity of which commences near this point. 

The cylinder-escapement is generally used, but any other 
dead-beat escapement may be substituted for this ; we shall 
enter upon the details of this escapement in the chapter 
devoted to the subject, only saying here that, in good 
watches, the four pivots, at least, of the two pieces of the 
escapement revolve in holes made in jewels which are 
adjusted to the pillar-plate, or upon the bridges. 

Figure 2 represents the second surface of the pillar-plate 
on the side of the dial, figure 1 having shown the surface 
on the side of the wheels. We see in Fig. 2, at P, an 
opening in which the cylinder constituting the barrel can 
turn without any friction against the interior of the open- 
ing P ; this gives facility for the largest possible spring, 
as the barrel may be raised almost to the dial. We also 
see in Fig. 2, a barret, N, which is fastened to the pillar- 
plate by two screws. This barret receives, at a, the pivot 
of the small centre-wheel ; at b, that of the crown-wheel, 
and at c, that of the escapement-wheel. This barret is 
edged off beneath, in order to give to the brass the requisite 
thickness relative to" the length of the pivots. 

We see in the same Figure 2, a second barret, 0, which 
is called chariot. This barret has, near its centre, a project- 
ing part, E, of the thickness of the pillar-plate. This part, 
B, enters a notch of the same form, which is made in the 


pillar-plate, reaching to the level of the other surface, and 
is adjusted loosely enough to permit a movement of three 
or four degrees or more to the right or left ; the reason of 
this we shall soon explain. This slide is first fastened with 
a screw, s. 

The cock L (Fig. 1) is not fixed upon the pillar-plate by 
the screw, t, but is fastened to it by the part R, of the 
chariot, 0, and by three chicks which are marked there. 
We see at d, on the same chariot, the place of the pivot of 
the cylinder. We can readily conceive that, if the two 
pieces are closely fitted and fastened together, the chariot, 
O, being also fastened upon the pillar-plate by the screw, s, 
the point, d, in which the lower pivot of the balance rests, 
can describe a small arc of a circle about the point s, and 
that by this means the cylinder can approach or recede 
from the centre, c, of the wheel ; the escapement can thus 
be rectified at pleasure if in the adjustment of the two 
pieces composing it any error is perceived. 

To guard against this inconvenience, a screw with a large 
head, T, is sunk into the pillar-plate ; this screw supports a 
notch, v, into which a steel pin, fastened to the end of the 
chariot, enters, so that by turning the head a little to the right 
or left with a turn-screw, the cylinder is moved to the requi- 
site distance from the wheel. When the escapement is fixed 
a datum is marked on the pillar-plate, and the screw, t, of 
the cock is clamped ; the escapement is thus securely fas- 

The point most worthy our present consideration is the 
construction of the barrel-arbor ; this differs in the Breguet 
and demi- Breguet watches. We are ignorant of the name 
of the inventor of the last, who seems to have adopted it 
because he found the system of the ingenious Breguet too 
difficult to execute. This system, however, has been gene- 
rally admitted into the Parisian workshops, that of Breguet 


alone almost exclusively preserving the construction of this 
skilful artisan. We shall first describe the system of the 
demi-Breguet, as it will better enable us to understand the 

Figure 3 gives an idea of the adjustment of the barrel- 
arbor to the demi-Breguet watches. The whole rod, from 
one end to the other, that is, from a to 6, comprising also 
the circular plate c?, is of a single piece. The barrel is 
contained with its cap in the elevation c, at the middle 
of which a hole, w, may be seen, pierced quite through ; 
on this cylindrical part, c, the cylinder, m, is placed, whose 
diameter is equal to one-third of the inner diameter of the 
barrel ; the motive spring revolves on this piece. But as 
these two pieces must be solidly and indissolubly joined to- 
gether, these two holes are pierced at the same time ; they 
are then fastened together by a good steel pin, which pro- 
jects on the side in order to form a hook capable of hold- 
ing the spring securely. As the barrel will rub upon 
the plate d, the friction of the whole diameter would be too 
great ; it is therefore turned on an inclined plane, so that 
the barrel rests on the smallest base consistent with solidity. 

The rondelle, f, is then arranged upon the barrel-arbor, 
a, b (Fig. 3), of the thickness of the bridge, C C (Fig. 1), 
and it is then adjusted above the cog-wheel, g, which is fas- 
tened to this round-plate by three screws, as may be seen 
in b (Fig. 1). 

We see in the figures 4, 5, 6, 7, 8, and 9, the details of 
the Breguet bridge, and the adjustment of his barrel-arbor. 
Figure 4 shows the bridge as seen above, and furnished 
with its click-spring. 

Figure 5 shows the same bridge as seen beneath, but 
without the spring ; this is seen separately in Figure 6. 

Figure 7 shows the barrel- arbor in profile, and at the side, 
in g, the front of the ratchet-wheel. 

22 the watchmaker's manual. 

1 i ;ure 8 shows, on a quadruple scale, the adjustment of 
the piece of steel which increases the size of the arbor to 
the requisite proportions, and which supports the hook de- 
signed to hold back the spring. All the other figures are 
on a double scale for a common-sized caliber. The same 
letters designate the same pieces in all the figures. 

The bridge (Fig. 4) is not of a single piece ; it is composed 
of the so-called bridge, whose thickness in the upper part, 
b, b (Fig. 9), we may consider divided into three equal parts ; 
one, m, forms a single piece with the bridge ; the second, 
/;, &, supports a socket, a, which is joined to the bridge by 
the screws, 5, b (Fig. 4) ; the third is hollowed in the mas- 
sive part of the bridge, and serves to contain the cog-wheel. 

The socket, a, of which we have just spoken, is designed 
to receive the end of the key when the watch is wound up, 
so as to preserve the other parts from any accident caused 
by unskilfulness. 

The main-spring, d, c, is edged off from / to c to about 
one half its thickness, so as to leave it no superfluous 
strength. It has an orifice or elongated opening at / to 
bevel the teeth of the cog-wheel. The upper part, c, is filed 
off to an inclined plane, so as to enter between the teeth of 
the cog-wheel and prevent them from falling back. This 
screw is fastened on the thick part of the bridge by a screw 
and two chicks, as in figure 6. The barrel-arbor (Fig. 7) is 
of steel and is in a single piece, and includes the cog-wheel, 
s, which is seen in the front and side at q. The part, o, n, is 
filed square, all the rest is round with the exception of the 
rods, p and r, which are squared for the remontoir. Upon 
the two angles opposite the same diagonal, two small notches, 
o, w, are made, and a steel cylinder, whose diameter is equal 
to one-third of the interior diameter of the barrel, is placed 
squarely upon this part. Figure 8, which is on a scale 
double that of the other figures, will explain this arrange- 


ment. Upon the prolongation of the diagonal of the square, 
?*, which is at the centre, a hole is pierced on each side and 
at an equal distance from the two angles. When these 
holes have been wormed out, two flat-headed screws are 
sunk in them, and a notch is then made in each at right 
angles, large enough to permit the passage of the square. 
"When this piece is in its place, each screw is turned a quar- 
ter round ; the thick part of the screws is then turned into 
the notches, o, n ; the screws serve as a key, and the whole 
is perfectly solid. 

In these two systems a particular construction of the pin 
that holds the minute-handle is adopted. Instead of pierc- 
ing the pinion, which in the old system was placed in such 
a manner as to rub against the lengthened rod of the axle 
of the large centre- wheel, the order is reversed. The pinion 
of the large centre-wheel is pierced through its axle, the 
pin of the minute-handle is replaced by a thick pinion, 
whose lower rod enters the hole made in the first named 
pinion, with friction enough to cause it to be drawn along, 
like the pin, and this rod bears the pivot of the large centre- 
wheel. In this manner, the upper rod of the pinion, which 
replaces the pin of the minute-hand, can be more lightly 
held, and the sockets both of the hour and minute- wheels 
sustain less friction. 

We think that we have described these two systems 
intelligibly enough to be understood by every intelligent 

The watchmakers of Geneva and Switzerland have gene- 
rally adopted these systems, but their patrons, finding that 
flat watches could thus be obtained, have abused this ad- 
vantage, and required watches so exceedingly flat that the 
artisans have found it impossible to make the springs as 
large as in the Breguet watches ; the rods of the axles of 
their wheels being very small, the oil soon gets into the 

24 the watchmaker's manual. 

pinions, and the watches are spoiled. It is not uncommon 
to see these watches so flat that the wheels have not the 
requisite play, and rub against each other in such a manner 
as to destroy all regularity. As a general rule, we protest 
against flat watches, and the low price at which they are 
sold is in itself a proof of their inferiority. 


As soon as clockmakers had succeeded in making clocks 
to mark the seconds, they sought the same advantages for 
watches, but here they encountered much greater obstacles. 
In clocks, the greatest regularity is sure to be secured by 
the slow vibrations, aided by a heavy pendulum ball and 
small arcs of oscillation ; in watches, on the contrary, the 
slow vibrations and heavy balances necessitate large arcs, 
and all concur in rendering the mechanism defective. 

All watchmakers know that a good and easily -regulated 
watch should beat from seventeen to eighteen thousand 
strokes per hour. The number of 14,400 strokes, as indi- 
cated by Berthoud, was adopted in this experiment, and, 
following his caliber, which places the pinion of the crown- 
wheel just above the figure 6 on the dial-plate, a small 
hand was placed on the pivot of this pinion, which turned 
round once in a minute, and marked the seconds on a 
small dial traced for this purpose ; these were indicated by 
four equal divisions. 

This construction did not satisfy those persons who 
wished to make exact observations, and, although they 
adopted dead-beat escapements, the small size of the dial, 
the nearness of the divisions, and the skipping of the needle, 
caused disagreements and rendered this method useless to 
them. They wished that the three hands should be con- 



centric, that they should all mark on the same dial, and 
that the hand should mark the dead seconds. They suc- 
ceeded in obtaining a greater degree of correctness by the 
following method, which increased the number of vibrations 
to 18,000 per hour or five per second. 

The escapement wheel under the dial was lengthened out, 
its pivot being supported by a high bridge, and a small cap 
bearing six pins at equal distances from each other, was 
fixed upon this rod. These pins, fixed perpendicularly 
upon the surface of the cap, performed the functions of a 
pinion which worked into the teeth of a cog-wheel placed 
upon the rod of the minute-hand pin. This cog-wheel 
had sixty teeth which were held back and fastened by a 
catch and moved upon two pivots, being impelled by a 
slight spring. Upon the socket of this wheel the second- 
hand was lightty fixed in perfect equilibrium. This me- 
chanism can be easily understood ; whenever a pin impels 
a tooth of the cog-wheel it also raises the catch which, as 
soon as the tooth has passed the angle thus formed, forces 
the wheel to move from one division to the other, retaining 
it there until another pin repeats the movement. The 
cylinder- wheel has fifteen teeth, thus giving thirty beats to 
the balance in each revolution ; and as it beats five times 
in a second, six seconds are required for an entire revolution. 
It is for this reason that the cap has six teeth and presses 
six teeth of the cog-wheel forward in the same number of 

It was soon perceived, however, that although this 
arrangement accomplished the purpose for which it was 
designed, it was still very defective on account of the force 
which was borrowed from the escapement- wheel to lift the 
click and impel the cog-wheel. An attempt was made to 
perform this function by the pinion of the crown-wheel, 
but, as this turned in the contrary direction, it was neces- 




sary to add a roue-de-renvoi ; this increased the friction 
without giving any real advantage, and this system was at 
length abandoned. 

Finally, in order to obtain this end without altering the 
movement of the watch, the idea of marking the dead 
second by an individual train, independent of the train 
acting upon the escapement, was conceived. This little 
train which we are about to describe has, for its motive- 
power, a spring enclosed in a particular barrel which is 
wound separately with the same key. It has no other 
function than to turn a train designed to mark the seconds 
by means of a hand which is concentric with the minute and 
hour hands, and which makes sixty uniform steps in each 
circuit of the dial. 

We shall first give the number of wheels and pinions of 
the watch, and shall then explain the mechanism of the 
movement of the hand. 

Number of teeth of wheels and leo.ves of pinions required in 
second watches. 

Teeth of 

Leaves of 




per hour. 

Wheel of the barrel . 


Large centre-wheel . 


— — 10 . 


Small centre-wheel 


— 8 . 




" — — - 6 . 

. 15 

Cylinder-wheel . 

15 ~~ 

~^^^6 . 

. 600 

The cylinder-wheel, having fifteen teeth, makes thirty 
beats at each revolution, and, consequently, 18,000 beats 
per hour or 5 beats per second. 

The small train is composed of five wheels and four 
pinions, as follows : 

First wheel upon the barrel arbor 

Second wheel . 

Third wheel . 

Fourth wheel, for beating seconds 

Fifth wheel 

Fly ...... 


Ee volutions. 





All of these wheels are eccentric to the pillar-plate, except 
the fourth, whose pinion of 8 is pierced like a minute-hand 
pin and revolves freely upon the rod of the large centre- 
wheel which traverses the dial. 

The socket of this fourth wheel carries the second-hand, 
and makes, consequently, one entire revolution per minute; 
this hand passes over the circumference of the dial in sixty 
equal strokes, independent of the movement which marks 
the hours and minutes. This is done as follows. 

The fourth wheel of this additional train turns once in 
sixty seconds, working into a pinion of 8, which it causes 
to turn seven and a half times during its revolution. This 
pinion of 8 carries the fifth wheel of 48 which works into 
a pinion of 6, which acts as a fly ; it causes this to turn 
eight times during its own revolution, and consequently 
this makes sixty turns while the fourth wheel makes one, 
which is one revolution per second. 

This small train is arranged upon the pillar-plate of the 
movement in such a manner as to place the fly-wheel very 
near the pinion of the cylinder- wheel without touching it. 
It is necessary, however, that the leaves of this pinion 
should check the rotary motion of the fly-wheel or permit 
it to turn ; this is done as follows : 

The pinion of the fly-wheel bears upon its rod a small 
brass pallet, which is longer than its leaves, and long 
enough to enter easily between the leaves of the pinion of 
the cy linder- wheel ; it then follows the motion of the 
cylinder- wheel as long as it is joined to it, but as soon as 
the leaf of the pinion permits the little pallet to disengage 
itself, it turns round and enters the tooth of the preceding 
pinion, continuing this as long as the watch goes. The 
movement of the pinion is suspended during five beats ; 
that is, during one second, since the watch beats 18,000 

28 the watchmaker's manual. 

A small detent, which the observant presses with his 
finger, checks the train at will, and hinders its motion as 
long as may be wished. 

This method, however ingenious it may be, does not yet 
present that degree of perfection which these machines 
should possess, particularly those which are designed for 
astronomical observations; it is, however, tolerably well 
adapted to the purpose. We cannot deny its extreme 
ingenuity, which will doubtless lead to the desired per- 


Repeaters are those watches which strike the hours and 
quarters indicated by the hands, by the compression of a 
pusher in the inside of the case. They differ from the 
simple or common watches that we have described, by a 
second train which is solely designed to strike the hours 
and quarters pointed out on the dial, and by pieces of steel 
styled dial-work, because they are usually placed beneath 
the dial. These pieces, when in repose, that is, when they 
are not set in motion by the action of the pusher, have a 
fixed place. Their functions are entirely independent of 
those of the train which impels the balance, so that this 
movement marks the division of time as in the common watch. 
It only winds up the small train and puts it in motion when 
the spring in the interior of the case is compressed. But 
this small train will not displace any piece of the dial- work, 
or strike the hour, if it is not pressed down as far as possible, 
thus causing a slight sound. This displaces the pieces of 
the dial-work, they leave their rest, and, while the small 
train is' restoring them to their first position, it comes in 
contact with the knobs of the hammers, and causes them to 



strike upon a bell or steel spring the number of single and 
double strokes of the hours and quarters indicated on the 
dial. Figure 10, Plate II., shows the arrangement of the 
pieces of this dial-work. We find at the present day two 
systems of dial- work in the watchmaking trade. We shall 
first describe the composition of the small or repeating 
train, and shall afterwards speak of the two systems. 

The repeating train is composed of five wheels and five 
pinions. It is placed on the edge of the large pillar-plate, 
in the space between the crown-wheel and the barrel. The 
effect of this train is to regulate the interval between each 
stroke of the hammer. 

The first wheel, also termed the large striking-wheel, 
bears a catch and a small spring upon which a cog-wheel 
works that forms a part of the arbor or axle of this wheel ; 
this forms a click and spring-work which gives way when 
the axle turns in a contrary direction to that in which the 
wheel ought to turn to set the whole train in motion. The 
arbor of the great wheel serves at the same time as the barrel- 
arbor, to support the little spring which impels the train. 
This little spring, which turns spirally like that of the 
movement, is placed in a small barrel fixed to the small 
pillar-plate by two screws. The following number of 
wheels and pinions is requisite : 

Teeth of 

Leaves of 




First or large wheel 

. 42__ 


Second wheel 


~^-^6 . 


Third wheel 


"^—6 . 


Fourth wheel 


~^ 6 . 


Fifth wheel 


~- 6 . 


Delay pinion or fly 

~-— --6 . 


The axle of the large striking-wheel, independently of 
the ratchet-wheel, bears another cog-wheel which is de- 
signed to set the large hammer in motion by raising its 

30 the watchmaker's manual. 

knob. This cog-wheel is usually divided into twenty-four 
equal parts, half of which are then cut off, leaving twelve 
which are designed to strike twelve strokes for the twelve 
hours. Dividing the number 4812J, the number of 
turns made by the fly-wheel during one revolution of the 
great- wheel, by twenty-four, we have for the quotient 200J, 
which is the number of turns made by the fly-wheel at 
each stroke of the hammer. Two hammers of cast-steel 
are placed in the interior and upon the edge of the frame. 
Each hammer is firmly mounted upon an axle of tempered 
steel, terminated by two pivots ; one of which revolves in 
the small, and the other in the large pillar-plate, where 
they are lengthened out, as we shall presently see. The 
rod of the large hammer is placed between the crown-wheel 
and the large striking- wheel ; its body passes around the 
crown-wheel, and its head is as high as the train will per- 
mit, so that it may strike as heavily as possible. Figure 
11 shows the large hammer with its knob. 

Upon the rod of this large hammer, a steel socket is placed 
which bears, in the frame, a sort of tooth or knob, m 
(Fig. 12), which works into the twelve-toothed cog-wheel 
that causes it to strike the hours. This socket, which is 
called the knob, supports the pin, 1, which passes through 
the circular opening (Fig. 10) for a purpose which we shall 
presently mention. This same pin causes the large hammer 
to move when the knob, m (Fig. 11), is caught by the notches 
of the twelve- toothed cog-wheel of which we have spoken. 

Independently of the pin, 1, of the knob, the large hammer 
has two other pins, 2 and 3, solidly fastened to its body by 
screws, which traverse the large pillar-plate and pass to the 
dial-work through the circular openings 2 and 3. The pin 3 
(Fig. 11) is further from the axle, q, of the hammer, than is 
the pin 2 ; the spring, g (Fig. 10), acts against this pin on the 
side of the dial- work. This spring is strong, and, working 


by a long arm, thus causes the hammer to strike loud blows 
to distinguish the hours. 

As soon as the hours and quarters are struck, the knob, 
ra (Fig. 11 and 12), is reversed by the method we have 
indicated in the description of the dial-work. This knob 
is no longer caught by the teeth of the cog-wheel, and the 
pin 1, which- it carries, is separated from the hammer. 
The quarters are struck by the pieces of the dial- work 
which come in contact with another knob placed beneath 
the dial. 

This explained, we will now describe the dial-work, 
which Figure 10, PL 2, shows all the pieces in action. The 
pusher, p, acting upon the arm, t, of the rack, C, has pushed 
the latter forward. It has a double function in this move- 
ment : first, by its arm, a, it draws the chain, c, which passes 
at first over the return-pulley, B, and rolls itself round the 
pulley A; this pulley is adjusted to the arbor of the small 
striking-spring, and bears the knob, cZ, which is fastened to 
the axle by a pin. In this first function, the rack causes 
the pulley to make almost an entire backward revolution 
while twelve hours and three quarters are striking; secondly, 
by its second arm, b, the rack rests upon the snail, E, whose 
depressions determine the number of blows which should 
be struck to mark the hour designated by the watch. 

This snail, E, is fixed by two screws to the star- wheel, D, 
which has twelve teeth fastened by the jumper, S, which at 
each revolution made by the minute-hand pin, presses 
forward one tooth of the snail ; that is, one tooth per hour. 
These two pieces, the snail and star-wheel, are carried 
by a rod proceeding from the end of the screw, F, which is 
wormed into the piece of steel, Gr, known as the all-or-nothing- 
piece. The end of this rod, F, enters into a hole in the 
pillar-plate, which is large enough to give the rod space to 
move a little when the snail is pushed forward by the arm b. 

32 the watchmaker's manual. 

The all-or-nothing-piece, Gr, is an important piece, the con- 
struction of which should be well understood in order to 
appreciate its effects, which combine with those of the motion 
of the quarters to prevent errors, and to secure the correct 
striking of the hours and quarters indicated by the hands. 

The all-or-nothing-piece, Gr, has its centre of motion at the 
point T, on the rod of a screw resembling the screw F, which 
is wormed into the all-or-nothing -piece, and which enters into 
a little socket riveted to the pillar-plate in order to raise it 
to the proper height. Its other extremity rests upon the 
arbor, f, which is wormed into the pillar-plate. This 
arbor passes through the all-or-nothing-piece and enters 
into an oblong hole, thus giving the all-or-nothing -piece a 
slight backward movement at the moment in which it 
comes in contact with the arm, b, of the rack. As soon as 
the pressure ceases, the all-or-nothing -piece is restored to its 
first position by the small spring h, which acts on the 
arbor, f, in a notch made in it. The button, /, prevents the 
all-or-nothing -piece from springing up. The hole, h, is designed 
to permit the passage of the end of the fusee so as to give 
facility to the winding of the watch. 

The end, H, of the all-or-nothing-piece is somewhat bent 
and ends in the apex of an acute angle. The arm, m, of 
the motion of the quarters rests on the corner of this angle 
when in repose. 

The motion of the quarters, Q, is of tempered steel ; the 
centre of its motion is i; it is pushed forward by the spring, 
I, in order to cause it to fall on the snail of the quarters, N, 
which is carried by the minute-hand pin, and on which it 
rests by its arm, n. It carries three teeth at each end, so as 
to strike a double blow at each quarter ; the three teeth, J, 
act on the knob of the large hammer, while the three teeth 
L, act on the knob of the small hammer. Its arm, o, when 
the arm, m, rests on the end of the all-or-nothing-piece, pushes 


the pin 1 of the inner knob of the large hammer and 
prevents it from eoming in contact with the twelve-toothed 
cog-wheel, placed in the interior of the frame. A pin, \ 
fixed upon the motion of the quarters, connects this piece 
with the knob, d, which it brings back to a state of rest. 
The knob of the large hammer, q, has two arms ; the upper 
arm comes in contact with the teeth of the motion of the 
quarters, and the lower one, with the pin which holds each 
hammer, and which passes through the circular apertures 
made in the pillar-plate. Each of these knobs is placed upon 
the axle of its respective hammer, the end of which passes 
into the dial- work. The spring, g, as we have already said, 
moves the large hammer, and the spring u the small one. 
Another spring, not designated in the figure, has a double 
use; it acts upon the notch of the outer knob, q, of the 
large hammer, hindering it from springing up and moving 
out of place, and, at the same time, pushes forward the pin 1, 
of the interior knob of the large hammer so as to connect it 
with the twelve-toothed cog-wheel ; this also applies to the 
spring, w, which acts in the same manner upon the knob, r, of 
the small hammer, with the dial- work. As but two hammers 
are used in striking the hours and quarters, the effect of 
three hammers is produced by means of the two pins, 2 and 3 
(Fig. 11), which are fixed upon the large hammer at unequal 
distances from its axle. The interior knob causes the large 
hammer to go over a large space and give the loudest 
possible strokes ; the knob, q, of the dial- work causes the 
hammer to pass over a smaller space, striking more gently, 
and better according with the effect of the small hammer. 

If this description has been clearly understood, we can 
easily explain the effects of it, after which we shall describe 
the construction of the surprise of the snail of the quarters. 

By pressing the pendant of the watch, the pusher, p, is 
made to act on the arm of the rack, t; the latter presses 


34 the watchmaker's manual. 

forward the rack C, causing it to describe the arc of a circle. 
Daring this movement, the large arm, a, draws the 
chain, c, and turns the pulley, A, by tightening the 
spring of the small train. The knob, d, which carries this 
pulley, turns backward and abandons the pin, \ of the 
motion of the quarters against which it was resting. During 
this movement, the arm, 5, of the rack, reaches the snail, 
E, of the hours, and pushes the all-or-nothing -piece a little 
backward. Then the arm, m, of the motion of the quarters, 
being no longer sustained by the all-or-nothing-piece, the 
motion of the quarters, moved by the spring, I, quits its 
place, its arm, w, moves to rest upon one of the divisions 
of the snail of the quarters, !N", and the arm, o, of the motion 
of the quarters resting no longer on the pin, 1, of the inte- 
rior knob, this knob, pressed by the spring, has a double 
effect, returns with the teeth of the twelve-toothed cog-wheel, 
and suffers the repeater to strike. 

The pusher is then drawn back, so that it no longer 
presses upon the rack. Then the spring of the small train 
puts it in motion, the hour indicated by the hour-snail 
sounds, and the knob, c£, which in turning finds itself caught 
by the pin, ?, winds up the motion of the quarters. This, 
acting upon the knobs of the hammers, causes them to 
strike, after which it brings it back to its original place, 
where it is held in rest by its arm, m, which rests on the 
all-or-nothing-piece ; whilst, by its arm, o, it has reversed 
the inner knob, and brought it beyond the reach of the 
twelve-toothed cog-wheel. We see, in truth, that without 
the small recoil which is given to the repeating spring, the 
train would have moved off without any hammer having 

We have yet to explain the construction of the surprise 
of the motion of the quarters and its effect. 

Figure 13, PL II., shows the minute-hand-pin and the 


snail of the quarters, seen in perspective and beneath. The 
snail of the quarters is composed of two pieces — the snail, 
1ST, properly called, and the surprise, S ; these two pieces 
are of steel. The snail, N, is riveted upon the pinion of 
the minute-hand-pin, beneath which a socket is left to 
receive the surprise ; this is fastened by a small drop of 
steel which is adjusted upon the projection of the socket of 
the minute-hand-pin in such a manner as not to obstruct 
the surprise. The surprise carries a large pin, 0, riveted like 
a pinion upon this piece ; the rod which projects enters into 
the notch, y (Fig. 10), with room for the necessary play. 
The surprise was invented in order that the watch should 
sound the three quarters until the hand should have marked 
sixty minutes, after which the striking of the quarters should 
cease. This effect is produced in the following manner : — 

The pin, 0, causes the snail to leap forward at the rate 
of one tooth per hour. In this movement, it forces the 
opposite tooth of the star- wheel to push the jumper back- 
wards. As soon as the angle of the tooth of the star- wheel 
begins to pass beyond the angle of the jumper, the spring 
which impels the jumper forces the latter to fill up the 
space between the two teeth and pushes the pin, 0, forward. 
This pin, which is not confined, yields, and the surprise 
presents itself in such a manner that if the knob of the watch 
is pressed at the moment when the hand marks sixty minutes,, 
the motion of the quarters fails upon the surprise, and no 
quarter is struck. 

The end, D, of the minute-hand pin (Fig. 13) is filed 
square, so as to hold the minute hand. We see, in this 
figure, that the socket of the minute-hand-pin, C, D, is cleft; 
this is done in all good watches, so that this socket may be 
able to fly back on the rod of the large centre-wheel upon 
which it enters with sufficient friction to turn the minute- 
hand easily from one side to the other, and to prevent the 

36 the watchmaker's manual. 

socket from clinging to the rod, which sometimes happens. 
This precaution, however, is not taken by some artisans, 
who substitute small longitudinal clefts, into which they 
introduce a little oil in winding them. This is an error, 
and watchmakers should avoid putting oil into these clefts, 
for, besides its tendency to loosen the minute-hand-pin 
upon the rod which supports it, this oil is communicated to 
the pinion, and thence to the roue de renvoi, and forms a 
coom which will finally stop the watch. These clefts have 
a double use ; they give the pin a little spring on the rod, 
as we have already said, and facilitate its extrication, in 
case of clinging, by introducing a little oil, which, entering 
between the pin and the rod, loosens it. The watchmaker 
should carefully remove every trace of this oil as soon 
as the minute-hand-pin is extricated. This clinging, as 
we well know, drives many watchmakers to despair, but 
good workmen make a pomade of oil and wax, a particle 
of which they place upon the rod of the large centre-wheel. 
This pomade does not run, like the oil, and does not cause 
any of the evils which the oil entails. 

We have already said that two systems of repeating 
watches are now found in commerce; we have just 
described the old system as perfected by the best artists. 
A word remains to be said in respect to the new system 
adapted to the flat watches known in commerce by the 
name of the Lepine caliber. 

We seem to owe to Lepine the idea of this new system 
which, we think, is not very successful. The pieces are the 
same as in the repeater which we have just, described. He 
suppresses the chain, c, and the return-pulley, B. He gives 
a new arrangement to the pieces of the dial- work, in order to 
draw the pulley, A, nearer the rack. He designs his rack in 
such a manner that it is terminated by the arc of a circle, 
the length of which equals the circumference of the pulley 


A. These pieces are placed against each other and near 
enough to permit the rack, by a hard friction, to impel the 

We see that the author has drawn this idea from the first 
repeaters, in which the rack was notched, and worked into 
a pinion supported by the barrel-arbor of the small train. 
The effect produced by the gearing was certain, bat we do 
not approve of the attempt to obtain this by friction alone, 
as this construction constantly tends to destroy the effect 
which is sought. 

We should also say a word in regard to some changes in 
the dial-work of the repeaters made by Breguet. This 
skilful clockmaker has suppressed the chain and the two 
pulleys upon which it was rolled in the ancient dial-works. 
This suppression has necessitated a change in the form of 
the rack, to which he has given teeth that work into a 
pinion placed squarely upon the rod of the barrel-arbor of 
the small train. He has thus obtained a little more empty 
space in the dial- work and has remedied one of the common 
accidents of repeaters — the elongation of the chain which 
causes them to strike wrong and often demands the loss of 
much time in repairs. 


The alarm- watch is a watch which, independently of the 
mechanism common to all watches and which serves to 
show the exact division of time, has another small train 
which, at a fixed moment, by the aid of a double hammer 
striking upon a bell, produces a sound loud enough to 
awaken a sleeper. 

The construction of alarms has changed much since the 
idea of applying them to watches was first advanced. The 

38 the watchmaker's manual. 

most simple, as described by Ferdinand Berthoud, were 
those which, carried a small dial placed in the centre of the 
dial of the watch, and which were turned by hand ; but 
this construction was in bad taste and was adjusted with 

Lepaute in his Treatise upon Clockmaking, page 115, has 
given a description of the construction in general use, which 
is much more correct and elegant than any before adopted. 
We will explain it. 

Figure 14, PL II., shows the pieces which are under the 
dial, and which constitute this kind of alarm. We see in 
this same figure, in dots, the wheels of the movement, those 
of the alarm, and its hammer. 

The cog-wheel, A, impels the hammer, F, G, with great 
rapidity. The train that impels the cog-wheel, A, is 
composed of two wheels and two pinions. The wheel C 
is carried by a barrel which encloses a mainspring which 
impels this wheel ; it works into a pinion supported by the 
wheel B, which works into a pinion whose rod rises under 
the dial and bears the cog-wheel A. 

The rod of the hammer, F, Gr, passes under the dial and 
supports squarely, at D, a pallet which works into the teeth 
of the cog-wheel ; it also supports a fork which receives 
between its prongs a tooth carried by the piece E. This 
bears a second pallet which also works into the teeth of the 
cog-wheel, A. These two pieces form together a species of 
double-lever escapement. 

When the cog-wheel is free, it impels the hammer alter- 
nately, which strikes upon the case or upon a bell. But 
when the alarm should not sound, the hammer is confined 
by a pin, a, placed perpendicularly on its rod in the extre- 
mity of the detent. 

The detent, 1ST, a, is movable around a horizontal axle, 
L, I, in such a manner that when its extremity, N, is free 


to descend, the spring, K, M, which constantly presses up- 
ward, causes the part, a, to rise ; this disengages the pin 
and the hammer. The problem is thus reduced to finding 
how this part, 1ST, has the liberty of descending at the hour 
at which the alarm should sound, and why it is elevated 
the rest of the time despite the spring, M, K, which tends 
to lower it. For this, it must be understood, that the dial 
or hour-wheel is placed under the part, N, of the detent, 
which is rested on this wheel. Upon the dial, and under 
the hour-hand, Q, S (Fig. 15), is placed the alarm-hand, P, 0. 
This last hand is notched at c, and the notch is terminated 
in an inclined plane towards P. This hand is fixed upon 
the dial, with a slight friction, by a key. The socket of 
the hour-hand, Q, S, passes, without friction, through the 
hole in the alarm-hand, and the pin, Q, is placed upon this 
socket in such a manner as to enter into the bottom of the 
notch, c. In consequence of this, the hour-hand, in turn- 
ing, ascends the inclined plane, and carries with it the dial- 

When the alarm-hand, P, O, is placed upon the hour at 
which the alarm is to be struck, the pin, Q, which keeps 
the dial-wheel suspended, and consequently the arm, 1ST, of 
the lever, N, a (Fig. 14), is moved upon the plane of the 
alarm-hand, but the instant that it encounters the notch, c, 
the hour-hand and the dial-wheel sink down together, the 
arm, N, is lowered, the arm, a, rises, the pin, a, of the 
hammer is disengaged, the train of the alarm revolves and 
the hammer strikes. 

The stop-work, T, determines the number of turns to be 
given to the spring contained in the barrel in winding the 
alarm. The pallet, X, fixed upon the axle of the barrel, 
successively grapples the teeth, 1, 2, and 3, when the alarm 
is wound up, and at the last turn rests upon the large part 
and elevates 4. 


The use of the piece, E, H, V, is to cause the prompt and 
precise cessation of the motion of the alarm. In truth, 
when the alarm begins to sound, the extremity, K, of the 
piece, R, H, V, being upon the part, 4, the highest part of 
the stop-work, its other extremity, V, is removed from the 
pin and does not obstruct the motion of the hammer ; but 
at the moment in which the spring shall have finished its 
five revolutions, and that the pallet, X, shall be ready to 
rest at X, the part, R, will fall into the first notch, and the 
other extremity, V, which has a small half-circular opening 
to receive the pin, a, will suddenly check the hammer. 



We designate by the name of pendulum clocks those 
clocks for apartments which were formerly placed against 
the walls, and which now are generally set upon mantels, 
secretaries, consoles, etc. 

We shall not speak here of the cases in which the move- 
ments of these clocks are enclosed ; these do not belong to 
the province of the clockmaker, who only employs himself 
with the works. 

The wheel-work of the clock is composed of two trains, 
one of which serves to measure the division of time, the 
other is for the striking-work. Sometimes a second striking- 
train is added to sound the quarters ; so that there are two 
trains for the striking- work, one of which serves to sound 
the four quarters before the hour, while the other is espe- 
cially designed to strike the hours only. We shall speak 
further on this subject after having described the ordinary 
pendulum-clocks. We shall divide this chapter into three 
sections, in which we shall treat — 

1st, Of the pendulum-clocks known by the name of re- 

2d, Of ordinary pendulum-clocks. 

3d, Of pendulum-clocks striking hours and quarters, and 
repeating by the same movement. 

42 the watchmaker's manual. 

§ I. — Of Regulators. 

Clockmakers are in the habit of designating as regula- 
tors those clocks with a long pendulum beating seconds, 
and marking the hours, minutes, and seconds by three 
hands, usually concentric. Every clockmaker has one of 
these regulators in his shop, by which to regulate the 
watches and clocks which he makes or repairs. This kind 
of regulator, when constructed with a twenty -four hour dial 
and regulated to siderial time, is styled the astronomical 

Ferdinand Berthoud took much pains in the perfect exe- 
cution of this machine, which goes a year without winding. 
The only change which we propose to effect in his method 
is to substitute for the Graham escapement the pin escape- 
ment of Lepaute, which was not known when Berthoud 
wrote his Essai sur V Horlogerie, but which he afterwards 
described with many encomiums in his Histoire de la Mesure 
du Temps par les Horloges, vol. ii., page 30, which may also 
be found in the Traite oV Horlogerie, by Lepaute, and which 
we shall describe in the Chapter on Escapements. 

§ II. — Of Ordinary Pendulum Clocks. 

The ordinary mantel-clocks usually have two trains, one 
of which is designed for striking. These clocks generally 
have a pendulum, or long balance. The height of the case 
in which this mechanism is enclosed determines the length 
of the pendulum, and, consequently, the number of oscilla- 
tions which the clock should beat per hour. 

These clocks run with a spring, and generally go fifteen 
days without winding The striking-work is also moved 
by a spring, enclosed in a barrel, whose wheel has eighty- 


four teeth. This wheel works into a pinion of twelve, 
carried by the second wheel of seventy -two teeth ; the arbor 
of the latter rests upon the small pillar-plate, and is parallel 
to the notch-wheel, or counter, which has twelve unequal 
notches to determine the number of blows which the 
hammer ought to strike in conformity with the hour indi- 
cated on the dial. The second wheel of seventy -two teeth 
works into a pinion of eight of the third wheel of sixty 
teeth, which is called the pin-wheel. This carries ten pins 
equi-distant from each other, which are designed to raise 
the hammer. The following wheel is called the locking- 
wheel ; this has sixty-four teeth ; it revolves once at each 
"stroke of the hammer, and carries a single pin to arrest the 
striking- work. The locking- wheel, which carries a pinion 
of eight, works into a pinion of six, which carries the next 
wheel, called the delay-wheel, and having forty-eight teeth. 
The latter works into a pinion of six, which carries the fly. 

This construction with the notch- wheel is subject to some 
inconveniences. It often happens that the striking-work 
miscounts ; that is, that it strikes a different hour from the 
one indicated by the hands. We shall presently see how 
this inconvenience has been remedied. 

We sometimes see repeating-clocks ; these have a small 
train analogous to the train of the repeating-watches, 
with a dial-work based on the same principles. A cord, 
which passes round a pulley placed upon the barrel-arbor 
of the small repeating-train, serves to wind up the spring 
when the clock is to repeat. m 

§ III. — Clocks /Striking the Hours and Quarters, and Repeat- 
ing by the same Movement. 

The invention of these clocks dates almost from the 
birth of clockmaking, when watches and clocks were con- 


structed, which performed these four functions, including 
the division or measure of time, and were therefore called 
watches or clocks of four parts. One of these pieces has 
fallen into our hands which formerly belonged to the Bishop 
of Montauban in 1784 ; we shall speak of this in our Chap- 
ter on Escapements. As any license may be permitted in 
order to obtain a good construction, we shall not hesitate to 
change the dial-work, with the sole design of the improve- 
ment of the art. 

Figure 1, Plate III., shows this dial- work. The two 
racks, A and B, have a common centre in C. They are 
adjusted in the following manner: — the rack A bears 
an axle on which it is riveted, and two pivots, one of 
which revolves in the pillar-plate, and the other in a bridge 
fixed upon the pillar-plate by a good screw and two chicks; 
this rack is very near the pillar-plate, room being given for 
sufficient play. It carries twelve teeth, saw-formed and 
shallow upon the convex surface, and bears internally upon 
the concave surface twelve other ratchet-teeth, more pro- 
jecting than the first. 

The rack B is riveted upon a brass socket, whose aper- 
ture is well adjusted to the cylindrical rod of the arbor of 
the rack A, which passes beyond this rack. Eoom enough 
is reserved between the two racks for a sufficient play, so 
that they may not rub against each other. They are both 
in a frame between the bridge and the pillar-plate. The 
rack B has but three teeth on the outside and inside, resem- 
bling those of the rack A. 

The rack A bears an arm, D, fixed upon- it by two screws ; 
this arm, when the rack is free, falls upon the hour-snail, 
carried by the star- wheel, E, and thus regulates the number 
of strokes which the clock should strike. 

The rack B also bears an arm, F, fixed by two screws 
upon this rack in the same manner. This arm falls upon 


the divisions of the quarter-snail, Gr, and determines the 
number of quarters to be struck. 

A detent, H, which is continually pressed towards the 
racks, I, retains the teeth of the racks in proportion as they 
are raised up by the two teeth of the pinion, J, carried 
parallel to the movement by the prolongation of the rod of 
the locking- wheel ; this bears two pins diametrically oppo- 
site, designed to arrest the train when the hook of the 
detent, entering into the last and deepest tooth of the racks, 
permits the piece, K, which is riveted upon the detent, after 
having traversed the pillar-plate and penetrated into the 
train, to present itself before one of the pins of the locking- 
wheel and to stop the action. 

The pinion, J, also carries a piece in the form of an S, 
which serves to raise up the detent, as we shall see. 

The piece L is the principal detent, which sets the whole 
machine in motion, when it acts by the impulse of the 
movement. This piece has its centre of motion at the point 
a, upon a small axle, supported by the pillar-plate and a 
small bridge. It is continually impelled to move forward ; 
that is, towards Gr, by the effort of the spring b. This 
detent bears by a hinge, at the point M, the horizontal piece, 
M 1ST 0. This last piece detains the train in the following 
manner : The piece, L M, bears an arm at c, which is on an 
inclined plane on the side of L, and is cut horizontally in 
the direction of the centre, Gr. The minute-wheel, which 
passes under the quarter-snail, Gr, bears four pins, placed 
towards the four extremities of two diameters, and perpen- 
dicular to each other. Three of these pins consecutively 
are a little nearer the centre than is the fourth. These three 
pins only push the detent, IT, far enough to permit the pas- 
sage of the quarter-snail ; the fourth permits the detent, L, 
to push it still farther, the two racks then fall at the same 
time ; that of the hours falls and strikes the hours, while 

46 the watchmaker's manual. 

that of the quarters is sustained by the snail and thus 
strikes no quarters after the hour. We shall see in a mo- 
ment the difference necessary to cause it to repeat. 

The detent, L, in springing back, draws along the hori- 
zontal piece M N O. We see that at the point O this piece 
is narrower, and presents a sort of step. The piece L M, 
in springing back, by the effect of one of its four pins, 
causes the notch, O, to fall in front of the upper part of the 
detent, H, and when the pin has passed, the spring, b, pushes 
the piece L M, and, consequently, the piece N O ; this 
forces the detent, H, to recoil, disengages the train, and lets 
fall the racks. The teeth, J, then lift up the racks, the 
piece in the form of an S, which they carry, raises the part 
N" O, and hinders it from catching the detent, H, until all 
the hours and the quarters shall have finished striking ; the 
detent, H, then advances as far as the last and deepest tooth 
of the rack will permit, and the pallet, K, stops the train. 
By drawing the detent, H, backward, by the cord, d, the 
racks are disengaged, and the train of the striking-work first 
sounds the hours and then the quarters. 

When the hour -rack has finished its course and is ele- 
vated as much as possible, it encounters the end of the arm, 
f, which connects the knob of the quarter-hammer with the 
pins of the third wheel in order to make it strike double 
blows at each quarter. This is done in the following man- 
ner : The arm f g h (Fig. 2), movable upon the point i, 
behind the small pillar-plate, rests by the point, h, upon the 
end of the pivot, m, of the knob of the quarter-hammer; 
the other pivot, Z, rests by its point upon the end of the 
spring, k, in such a manner that when the rack, A, is at the 
highest part of its course, as represented in Fig. 1, the arm 
of the lever, A, is pushed forward, the arm, w, comes in 
contact with the pins, and the knob, jo, causes the hammer to 
move. But as soon as the rack, A, falls, the spring, k, repels 


the knob, it disengages itself from the pins, and the hour 
hammer strikes but one blow at each hour. 

We know of nothing more simple than this construction 
which has been generally adopted, and which is an applica- 
tion of the system followed from time immemorial in the 
Comte clocks. 



It is about a century since the advantage which is gained 
by placing all the wheels of a large clock on the same 
horizontal plane, instead of arranging one above another 
in a vertical frame, as had been previously done, was first 
perceived. This construction lessens the height of the 
frame, and renders the friction slighter, and the gearings 
more constant and less apt to vary from wear. We do not 
intend to speak at length concerning belfry clocks, but 
shall only describe the remontoirs which are adapted to 
these clocks, and which tend to increase the regularity of 
the working of the movement. 

The remontoir in clocks [see Berthoud's Histoire, vol. ii. 
p. 40] is a very ingenious mechanism, designed to obtain a 
perfect equality for the power which keeps up the movement 
of the regulator, so that this force shall not share in the 
inequalities of the gearings and the frictions, or in that of 
the mainspring, and consequently shall maintain a constant 
equality in the extent of the arcs of vibration of the regu- 
lator. To accomplish this, two motive powers are em- 
ployed. The first is that which turns the wheels of the 
train ; this is wound up by the hand every day or once in 
eight days ; the second motive power, on the contrarj^, is 
renewed every instant, or at very short intervals by the 
first motor, so that it is regarded to be constant and equal 
in action. We shall call this mechanism the equalising re- 


montoir, in order to distinguish it from the ordinarj^ remon- 
toir of clocks. 

The ancient artists who occupied themselves in perfecting 
the balance of clocks, long since perceived the necessity of 
preserving to this regulator arcs of an equal extent, in 
order to obtain for the clock all the accuracy of which it 
was susceptible. It is to this idea — alike happy and j ust — 
that we owe the first invention of the remontoir, or of a 
secondary remontoir, designed to render the force which 
sustains the movement of the pendulum perfectly equal and 
constant ; so that it may not 'participate in, or be affected 
by, the unequal forces which cause the variation in the fric- 
tion of the pivots of the movement, of the gearing, or in the 
inequality of the motive power. We owe the first idea of 
this mechanism to Hu} T gens, who made use of it in the first 
marine pendulum clock ; Leibnitz, after him, proposed the 
same method ; Gaudron and other artists have also used 
it ; and Thomas Mudge, the celebrated English artist, in- 
vented, in 1794, the best remontoir then known. Finally, 
in our own time, the celebrated Breguet has given us, un- 
der the name of the escapement of constant force, the best 
remontoir now in use. 

This ingenious mechanism is now generally adopted in 
the construction of all large clocks. A beautiful clock, 
executed by M. Wagner, has attracted the attention of con- 
noisseurs. The train of the movement had no action on 
the escapement- wheel ; it was only occupied in winding up, 
once in two minutes, a small weight which acted directly 
upon this wheel. 

A very beautiful clock, with an equalizing remontoir, 
may be seen at the Palais de la Bourse in Paris, which was 
executed by M. Lepaute, with great perfection, by a differ- 
ent method from that of M. Wagner, but performing the 
same functions. 



Hitherto, they had only succeeded in sounding the four 
quarters before the hour, by employing two trains for the 
striking- work, one of which struck the quarters, and the 
other the hours. This movement detained the train of the 
quarters ; the latter at each hour, after having struck the 
quarters, disengaged the detent of the train of the hours, 
which then struck the hour separately. 

M. Kaingo, sen., a clockmaker of Paris, occupied him- 
self with the solution of this problem ; he executed, in 
1828, an apartment-clock which had but two trains, and 
which struck the hour, the quarters, and the four quarters 
before the hour, with precision. This clock has a circular 
balance, with an Arnold detached escapement. It marks the 
hours, the minutes, the days of the month, the days of the 
week, and the phases of the moon. This clock is described, 
with figures, in the Bulletin de la Socieie d 1 Encouragement de 
Paris, of the month of April, 1828. We give here a frag- 
ment of the report made to this Society relative to the most 
important piece of this movement, which is very simple. 

" The hour-snail is cut as in the ordinary clocks striking 
three quarters, and there is besides a sort of surprise, formed 
by a movable snail, which is joined together beneath the 
first, and drawn along in its general rotation. This mova- 
ble snail remains unused except when necessary to strike 
the four quarters. The striking-work is regulated by a 
notched rack, in the manner of the Jura clocks ; the detent, 
which abandons it for a time, causes it to rest upon some 
point of the circumference of the snail, and by entering 
then into a notch, the range of the descent determines the 
number of teeth passed, and, consequently, the number of 
blows of the hammer ; the whole being in conformity with 
the mechanism generally in use, When the turn of the 
four quarters arrives, the time comes for the action of the 
surprise or movable snail ; a detent displaces it and it finds 


itself in another position. The principal merit of the in- 
vention consists in this ingenious surprise ; it will be seen 
that the clock will not miscount in the striking of the hours. 
This is the case with the Jura clocks which, in this respect, 
have served as a model to the author. Finally, a movable 
detent presents itself in such a manner as to permit but four 
blows to be struck in the parts of the snail where the sur- 
prise is not needed ; for this is only useful at four hours 
after noon on account of the arrangement of the notches of 
this piece." 

This invention is principally used in belfry-clocks which 
are designed to strike four quarters before the hour. The 
arrangement is rarely used ua mantel or apartment clocks. 




I. — Of the Metals used. 

Steel and copper (commonly called brass) are the two 
metals exclusively employed in the manufacture of all the 
pieces composing watches, mantel and apartment clocks, 
and regulators, not even excepting chronometers. Of 
course we do not now refer to the cases which enclose the 
movements, and whose execution does not belong to watch- 

Steel. — The clockmaker only uses cast steel, as it is the 
purest and most homogeneous. This may be obtained in 
all the forms used, whether in flattened plates of various 
thicknesses, or draw-plates, either for wires of every size or 
for pinions of every number and dimension, according to 
the general use. This steel is rarely flawy, and one might 
almost choose it blindly. 

Brass. — But such is not the case with brass ; this metal 
is not found originally in the mines, but is a product of 
art ; it results from the alloyage of zinc with the red copper, 
known as rose or refined copper, the best of which comes 
from Sweden. If tin is added to this alloy, a greasy metal 
is formed which is difficult to work ; it sticks to the file, 
and, when the proportion of tin is large, it becomes so hard 
that it is almost impossible to work it — it is absolutely bell- 


When, in the composition of brass, the rose-copper is 
alloyed with seven per cent, or more of zinc, and a small 
quantity of lead is added, a dry alloy is obtained which is 
turned and filed with great facility. It is necessary, how- 
ever, to be very sparing in the use of the lead, and careful 
in its choice as it must be very pure. From several expe- 
riments made with a view of obtaining a brass suited to 
clock-works, I am convinced that not more than one per 
cent, of lead should be used. When a larger quantity is 
employed, grains are formed which, though often very 
small, are so hard that the file takes no effect on them. It 
is especially necessary to avoid the introduction of mole- 
cules of iron or steel into the composition of the alloy, as 
they destroy the quality of the brass, and acquire so much 
hardness in the fusion that they will resist the best file and 
cut the hardest steel. 

We do not doubt that the bad quality of the brass, of 
which the clockmakers complain so much, proceeds from 
the causes which we have just mentioned, and that, if some 
intelligent metallurgists would take the necessary pains, 
they would succeed in finding an alloy which would pro- 
cure a perfect brass for the use of clockmakers. From 
numerous experiments which we have made, we have ob- 
tained an alloy composed of 

85 parts of pure rose-copper. 
14 parts of pure zinc. 
1 part of pure lead. 

100 parts. 

This alloy, which we have not been able to make on a 
large scale, seems to us to contain just the proportions. 

II.— Of the Fusee. 
The invention of the fusee, which Pierre Leroi, and, 

54 the watchmaker's manual. 

after him, Ferdinand Berthoud, unceasingly eulogized, is a 
mechanism which is infinitely useful in watches in render- 
ing the action of the spring equal to that of a motive 
weight. It has been generally adopted, yet it has several 
inconveniences which it would be exceedingly desirable to 

It was thought that the dead-beat escapement of Tompion, 
in 1695, might obviate the necessity of the fusee, and this 
idea, renewed whenever a new escapement was invented, 
and then contradicted by experience, has been revived in 
our day by some celebrated watchmakers, who have sup- 
pressed the fusee in their works. 

The detached escapements seem best suited to correct the 
inequalities in the mainspring, and to revive the hope of 
suppressing the fusee without affecting the accuracy of the 
watch. Many unsuccessful attempts with these have been 
made, but Berthoud has proved that no escapement can 
have any influence over the mainspring, and, consequently, 
that it cannot correct the inequalities of the motive-power 
from being transmitted to the balance, whose velocity is 
retarded or accelerated in conformity with the irregularities 
of the mainspring. 

Let us point out the inconveniences of the fusee, and 
compare them with the advantages which it possesses. 

1st. Without the fusee the spring would act directly upon 
the wheel-work ; the frictions are at least doubled by the fusee. 
If there was no fusee, the great wheel would be carried by 
the barrel or its arbor, and the spring would only have to 
overcome the resistance opposed it by the frictions of the 
two pivots of the arbor, in order to transmit the move- 
ments to the large centre wheel ; but when there is a fusee, 
the spring has first to overcome the resistance of the fric- 
tions upon the two pivots of its arbor, and then the frictions 
of the two pivots of the fusee-arbor. Now as these two 


arbors, having nearly the same diameter, oppose an equal 
resistance, the fusee consequently doubles the frictions, and 
it would be easy to demonstrate that it augments them in a 
much larger proportion. 

2d. The friction being augmented by the use of the fusee, 
a much stronger spring is therefore necessary. Now every 
one understands that in order to strengthen a spring, its 
breadth remaining the same, its thickness must be increased ; 
but this augmentation of thickness injures the spring, and 
makes it more easily broken, or sooner worn out. 

3d. The spring breaking, it becomes necessary to replace 
it with another, and every good clockmaker understands 
that he cannot then dispense with equalizing the fusee anew, 
if he does not succeed in finding a spring precisely like the 
first, which is morally impossible. If this accident hap- 
pens three or four times, it will be necessary to replace the 
fusee, and every workman knows the trouble which is 
experienced in replacing a fusee in towns far removed 
from the manufactories. 

4th. The fusee necessitates a chain, a chain-guard with 
its spring, and a hook of the fusee ; and the adjustment of 
all these pieces exacts certain precautions, which are so far 
beyond the skill of most workmen, that we rarely see 
watches in which the union of these pieces is perfectly exe- 
cuted — whence come the frequent breaking of the chain 
upon winding the watch. 

5th. In short, one has to run two chances for the derange- 
ment of his watch, either the breaking of the spring or of 
the chain. 

The only advantage which the fusee possesses in watches 
is that of rendering the effect of the mainspring equal 
through its course. 

The following advantages are presented in a watch with- 
out a fusee : — 

56 the watchmaker's manual. 

1st. Less friction in the transmission of the motive 

2d. The spring need not possess more than half the 
strength ; its bands will therefore be thinner, it will be less 
apt to break or to wear out, it can be longer, and its effect 
will be surer and less unequal. 

3d. In suppressing the fusee, all the pieces of the chain, 
the chain-guard, and the hook of the fusee are also sup- 
pressed ; we thus have a smaller motive power and a larger 
space in the frame by which to give the wheels the neces- 
sary play ; we can construct the watch more easily and to 
better account. 

4th. In the repeating, striking, carillon or alarm watches, 
in which the want of space exacts the multiplication of the 
wheels of the movement of the striking- work on account of 
the little room which can be given to each of them, a great 
advantage is gained by the suppression of the fusee. The 
number of wheels will thus be reduced as a greater diameter 
can be given them ; they will work more easily, and the 
small spring can be longer, with a thinner band, and con- 
sequently better. The potance can preserve the form which 
it bears in simple watches ; it will be more easily made, 
and the workmen will be able to diminish the price of their 

We may infer from the preceding facts that the invention 
of the fusee in watches, while correcting an essential fault, 
the inequality of the force of the mainspring, has intro- 
duced a number of inconveniences which its suppression 
would certainly remove, especially if the fusee could be 
replaced by some simple mechanism independent of the 
movement. These reflections suggested to us the idea of 
the construction which we shall now describe, and which 
we have published in the Annates des Arts et Manufactures, 
vol. xix. p. 72. 


Explanation of Figure 3, PL III. 

The barrel-arbor enters squarely into the central hole of 
the pinion, A, of 8 leaves ; this arbor is turned with a key 
to wind the watch. 

The pinion, A, turning to the right when the watch is 
wound, causes the wheel, B, B, to turn to the left. The 
latter bears a curve, C, fixed invariably with it in such a 
manner as to follow all the movements of the wheel. The 
points of the outline of this curve are at unequal distances 
from its centre of rotation, I ; from the point, D, which is 
farthest removed from it to the point, E, which is the 
nearest it. 

Against the sides of this curve a strong spring, G, F, acts 
continually, which is fastened to the point, F, by a screw. 
This spring, Gr F, bears at its extremity, Gr, a flange-roller, 
whose two sides surround the body of the curve so that it 
cannot quit it, and the curve rubs upon the bottom of the 
roller, which is flat, and rests continually upon the curve 
with a view of diminishing the friction. 

The screw, H, which we see placed at the extremity of 
the fixed part, F H, of the spring serves as a catch to it, 
and also gives the facility of augmenting or diminishing the 
force of the spring, F Gr, as circumstances may require. 
The screw, H, which has a neck, may be placed in several 
different ways ; it is either placed as in Figure 3, entering 
freely into the arm of the spring, and is wormed into the 
border ; or it enters freely into the border and is wormed into 
the arm of the spring. In both cases the same eifect is pro- 
duced in fastening the screw ; the arm, H, is drawn towards 
the border and a greater force is given to the spring ; in loosen- 
ing the screw a contrary effect is produced. The second 
arrangement is often the more convenient on account of the 


58 the watchmaker's manual. 

pieces which, being upon the pillar-plate, might destroy the 
effect of the turn-screw. A circular form may also be given 
to the screw by causing it to follow the outline of the 
border. As to the rest, the principle being once described, 
the form can easily be varied. 

The two concentric dotted circles, K, K, indicate the ar- 
rangement of the barrel fixed by two screws upon the pillar- 
plate, and of the great movement- wheel, that is carried by 
the barrel-arbor which we see proceeding squarely from the 
centre of the pinion, A. We know that a main-spring should 
not be too much bent, and that it should not be able wholly 
to unbend itself. In the one case it would be apt to break 
easily or soon wear out ; in the other, it would be in danger 
of unhooking itself from the barrel-arbor. To avoid these 
two inconveniences, when the fusee and the chain-guard are 
not used, a stop- work is commonly substituted. 

Our mechanism includes all these conditions ; the wheel, 
B, B, bears a large tooth against which a leaf of the pinion, 

A, props itself when the spring is bent or when it is unbent. 
Let us suppose that the spring can make six turns, and that 
but four turns of the great wheel are necessary to make the 
watch go for thirty hours. We should therefore give eight 
leaves to the pinion, A, and thirty -four teeth to the wheel, 

B, B, taking care to cut off but thirty- two of them ; by this 
means a large tooth will remain which will leave to the 
spring a turn of the band in these two extremes. 

The invention which we have just described must not be 
confounded with another mentioned by Ferdinand Ber- 
thoud (in his Histoire de la Mesuredu Tempspar les Horloges, 
vol. i., p. 77). This dates back to the fourteenth century, 
before the first use of the fusee, and perhaps suggested it. 
In this invention a straight spring, with the aid of a curve, 
opposed itself to the action of the main-spring when it was 
at the top of its band, and increased its action when the 


spring, being at the bottom, acted more feebly. Let us see 
the difference which results from these two constructions. 

In our invention when the main-spring is at the maximum 
of its tension, the point, D, is beneath the roller, and the 
spring, F, Gr, is likewise at the maximum of its tension ; 
the latter acting upon the large arm of the lever, destroys a 
part of the force of the main-spring. When, on the con- 
trary, the main-spring is at the minimum of its tension the 
point, E, is beneath the roller, and the spring, F, G, which 
is also at the minimum of its tension, can no longer produce 
any effect upon the main-spring, which acts with all its 
remaining force. 

Our mechanism differs essentially from the ancient method 
in this arrangement. In the ancient the spring, F, Gr, was 
subtractive during a certain time, after which it became 
additive ; while in ours it only acts as subtractive. 

1st. The double effect which we perceive in the spring 
of the ancient construction would be more difficult to exe- 
cute and could not be very sure ; this was probably one of 
the reasons which caused its abandonment. 2d. The curve 
should produce the same effect as the fusee which has re- 
placed it ; now the fusee does not produce this double effect 
which they professed to obtain by the aid of the curve. 
When the spring is at the maximum of its tension, it acts 
upon the fusee by the smallest arm of the lever, which aug- 
ments in proportion as the main-spring loses its force ; the 
curve should render the force of the main-spring equal, 
with the aid of the spring, F, Gr, by acting in an inverse di- 
rection to the fusee. The subtractive spring should oppose 
to the main-spring a greater resistance as the latter is tight- 
ened, and this resistance should diminish in the same pro- 
portion as that of the main spring diminishes. This is 
the effect produced by our curve when it is correctly 


Some details respecting the manner of executing the 
curve and the subtractive spring, seem to us to be useful. 
The rod which carries the wheel, B, B, is terminated by a 
square, and it is by this square that the curve is carried ; it 
is fastened there by a pin which passes through the square, 
and we thus obtain a facility of taking away the curve 
whenever necessary to cut it, and of replacing it without 
trouble. The curve should be of steel, its diameter, before 
being cut, is equal to the internal diameter of the wheel, B, 
B, and between this wheel and the curve a round shield of 
brass should be placed to separate these two pieces, so that 
the roller may not rub upon the wheel, B, B. The spring, 
F, Gr, should be as high as possible ; it should neither rub 
upon the pillar-plate nor upon the wheel, B, B. At its 
extremity, Gr, it bears the brass roller, which turns loosely 
upon its axle and continually rests upon the curve. 

The thickness and the force of the spring are determined 
by the force of the main-spring, but as we have observed 
that, in suppressing the fusee, we do not need as strong a 
main-spring, but can use a long spring with a thinner band, 
this spring, therefore, being weak, does not require a strong 
compensation-spring. This should insensibly diminish in 
thickness, so that it may be elastic through its whole length, 
and its movement should always be directed towards the 
centre, I, of the wheel, B, B. To determine the length of 
this spring we should describe an arc, Gr, I, from the point 
F, the centre of its movement, with F I for the radius, which 
will determine the length, F, Gr, of the spring, with sufficient 
precision ; the centre of the roller should always be found 
in the arc, Gr, I. 

All being thus arranged, we proceed to the cutting of the 
curve. For this, the main-spring being quite down, give it 
a turn upon its arbor and turn the wheel, B, B, until it pre- 
sents the large tooth to the pinion, so that the latter stops 


the return of the pinion backward and leaves the spring 
bent in one turn, which is the minimum of its tension. 
Take away the steel plate, which should be cut in a spiral 
form, and bring the roller of the spring as far as the centre, 
I, of the wheel, B, B, by the aid of the screw, H. Replace 
the curve after loosening the screw F enough to give to the 
subtractive spring the liberty of passing over the curve. Let 
it loosely approach the centre, I, and mark the point which 
the roller reaches. Then wind up the main-spring, which 
again should have a turn of the band at the point in 
which the tooth of the pinion is checked by the large tooth 
of the wheel. Place the subtractive spring in such a man- 
ner that the roller may be on the edge of the curve, encir- 
cling it, and mark the point at which the roller is found. 
The last point corresponds to the point D, and the first to 
the point E. Divide the surface of the steel plate which 
is to form the curve into eight or ten nearly equal parts, 
and trace as many radii to the centre I. Then, after having 
well fastened the screw F, remove the matter in the direc- 
tion of each radius by the aid of a round file until you 
find an equality of all the points of this spring by means 
of the arm for equalizing the fusee, which is placed on the 
arbor of the main-spring. This preliminary executed, pass 
a curve over all its points, then remove the superfluous 
matter, aud the curve is nearly finished ; then rectify it and 
polish the edges. 

We see with what facility this curve is cut ; it is isolated 
and can be removed without taking the frame to pieces. 
The place in which it should be touched can easily be seen; 
while to equalize a fusee, it is necessary to dismount the 
whole, often working at random and rarely sure of what has 
been done. 

The late M. Breguet knew nothing of this invention 
until the eve of his death. He spoke of it to us and from 

62 the watchmaker's manual. 

the description which we gave him, he approved it, and 
promised us that he would execute it, but his death pre- 
vented the performance of his promise. 

III.— The Barrel 

In all watches, whatever may be their construction, the 
barrel should be as large and as high as the caliber will 
permit. The best spring is that which is largest, with the 
thinnest band ; it thus becomes longer, the motive-power is 
less irregular, and it is less apt to break. 

Whatever system may be adopted — whether the fusee is 
retained or suppressed — a curb should always be given to the 
spring. This piece is a small steel band which is placed 
at the inner edge of the barrel, entering by one of its 
ends into the bottom of the barrel and by the other into the 
cover ; it is placed at nearly a quarter of the circumference 
of the barrel, reckoning from the hook which fastens the 
spring to the barrel. This curb, which Figure 14, PI. I., 
represents at a, at the side of the barrel-arbor B, whose 
hook is seen at c?, causes the first band of the spring to rest 
against the barrel, and thus protects the eye of the spring 
from injury. This eye cannot be made until after having 
annealed the extremity of the spring, which, in this part, 
has lost its force and elasticity. It is very important that 
its action should commence when the spring preserves its 
good qualities. 

The method which we have described in detail in the 
preceding paragraph can be executed in the different systems 
of watches which have been adopted, both in the common 
balance-wheel and the Breguet system. It is only necessary 
to make a slight change in the barrel, which should be 
fastened by two screws to the pillar-plate, or to a bridge like 
the small spring of the train of the repeater ; and its arbor, 


as in the same train, should carry the great wheel and the 
click and spring- work. The other pieces are beneath the 
dial and do not dispense with the use of the different stop- 
works of which we are about to speak, and which have been 
happily substituted for the chain-guard. 

IV. — Stopworhs of the Remontoirs. PL III. 

We designate, under the name of stopworks, those 
constructions which have been adopted in watches and 
clocks, to replace the chain-guards, or to regulate the 
number of turns which should be given the main-spring. 

Independently of that which we have adopted in our 
mechanism for the suppression of the fusee, several other 
kinds of stopworks have been invented which it is important 
to understand. 

1st. That represented in Figure 4. A round-shield, A, 
is placed upon the square of the fusee or barrel-arbor, and 
at its side is a star- wheel, B, carrying as many teeth, plus 
one, as the number of turns that the fusee should make. 
The round-plate, A, has a plate in its centre which is ele- 
vated to the thickness of the star-wheel, whose teeth are 
very large : these teeth are all depressed or filed in hollows 
in their middle, D, except the last, O, which is rounding. 
A steel tooth is fixed upon the round-plate at the point E, 
this pin works into the clefts of the star- wheel. At each 
turn of the round-plate, A, it passes one tooth of the 
star- wheel ; the middle of this tooth encounters the base of 
the round-plate which enters into its hollow and prevents it 
from turning ; but when the convex tooth, C, arrives, it 
can no longer pass, and the stop work is formed. 

2d. Another surer and more ingenious stopwork has 
been invented, whose construction is shown in Figure 5. 
A wheel, A, is placed squarely upon the fusee-arbor ; this 

64 the watchmaker's manual. 

square also bears a tooth or arm, B. The wheel A has 
twelve teeth, this works into a wheel, C, of ten teeth which 
carries an arm, D. After the fusee has made five turns and 
the wheel C has made six, the two arms, B and C, meet and 
prop against each other, thus forming a stopwork without 
wearing the teeth of the wheels. 

If we should place the wheels in a contrary direction 
without changing the numbers ; that is, if we should place 
the wheel C upon the fusee, and the wheel A at the side, 
the fusee would make six revolutions before encountering 
the stopwork. The numbers may easily be varied at plea- 
sure to obtain the stop at the desired moment. 

3rd. Figure 6 indicates a kind of stopwork invented by 
Lepine for very flat watches. A flat-bottomed cavity, a, 
is made in the pillar-plate, or rather in the cover of the 
barrel, as these watches have no fusee, in the middle of 
which a large drop is left in order to lodge therein a sort of 
spring in the form of the wheel B, cleft at &, and which enters 
into this cavity like a cover of a barrel ; on the opposite 
side, at the cleft b, as many teeth are made as are needed 
for the number of turns required for the spring. A steel 
wheel, A, cut in cogs, is placed upon the arbor ; a steel pin, 
c, is fixed in this wheel, which works into the teeth of the 
spring- wheel B, upon which it passes ; when this pin 
encounters no more teeth the stopwork is formed. This 
cog-wheel serves for the stopwork ; the click and spring 
are fixed upon the pillar-plate or the bridge. 

These stopworks, which are those most in use, can be 
varied in a thousand different ways, and may be adjusted 
to the fusee, or to the barrel when the fusee is suppressed. 

"V. — Of Workmanship in general. 
"We shall not go over all the pieces of clockwork, in 


order to describe the construction of each of them. As it 
is impossible in this art to replace by a book the practical 
advice which a good master can give in a sufficiently long 
apprenticeship, we will limit ourselves to giving some 
advice which will be useful at least to beginners. 

Of the working of brass. — When the best brass that can 
be procured of the required thicknesses has been chosen, it 
must be remembered that in this state the metal is too soft, 
and that it can only obtain the necessary hardness and 
tenacity, by being forged when cold with a good hammer, 
upon a hard, smooth hand-anvil. A plate of the metal of 
twice the thickness required for the piece, and of a little 
more than half the size indicated by the caliber, is first 
sawed. After having scraped the piece, that is, after hav- 
ing filed each surface with a rough potance-file, the piece 
is stretched in both directions and on both surfaces by 
successive blows with the face of the hammer, until it shall 
have acquired the dimensions fixed by the caliber, care 
being taken to remove with the file the smallest cracks 
which may be perceived on the edges, as they frequently 
affect the whole piece and render it defective. These cracks 
are generally caused by the unskilfulness of the workmen. 
There is another defect which should be avoided : that of 
bruising the brass and making it rise up in puffs. This 
fault is occasioned by too heavy blows, carelessly or falsely 
struck, and cannot be remedied. Such a piece is spoiled. 

We have seen some apprentices who, in forging small 
pieces, such as small wheels, cut their brass too large for 
fear of striking their fingers with the hammer. They con- 
tent themselves with levelling it, leaving the piece double 
the required thickness ; they are then obliged to remove all 
the superfluity, and their piece becomes soft. They are 
probably ignorant of the fact that the brass only becomes 
hardened in the surface which comes in direct contact with 

66 the watchmaker's manual. 

the hammer, and that when the piece is too thick thej 
remove all the hard surface with the burin. The forged 
piece ought to be as nearly as possible of the required 
thickness ; it should be cut as straight as possible, and 
when it is turned round and of the proper size, a light stroke 
should be made upon the two surfaces and the edges to 
indicate that it must be filed in order to render it perfectly 

Of the working of steel. — Nothing but cast-steel of the first 
quality should be used, and care should be taken in hard- 
ening it not to give it a greater degree of heat than a 
cherry -red, and to harden it in oil. Hardening it in water 
at this degree of heat would be apt to make it too brittle. 
Care should also be used in the tempering that each piece 
does not exceed the required color, so as to obtain the 
degree of hardness best suited to the uses for which it is 

All that we have said in this paragraph applies to both 
clocks and watches. 



By gearings \ we mean a system of wheels and of pinions 
whose circumferences are covered with teeth, and which 
act upon each other in such a manner that the movement 
given to one of them is communicated to all the rest by 
means of the teeth of wheels which enter into the teeth of 
pinions, the diameters of which are in a given proportion 
to those of the wheels. It is very essential that the gear- 
ings should be perfect, to cause the machine to go with a 
regular movement. 

u Perfect gearings" possess the following conditions : 1st. 
That the force employed by the wheel which conducts the 
pinion shall be as slight as possible. 2d. That the velocity 
with which the wheel impels the pinion shall also be, at 
every instant, as great as the wheel is capable of giving to 
it. 3d. That this force and this velocity shall be constantly 
the same from the point of meeting until the moment in 
which the tooth of the wheel abandons the leaf of the 
pinion and vice versa. 4th. That the friction of this tooth, 
during all its course, shall also be as slight as possible. 

All clockmakers know that the curve which affects 
the teeth of the wheels and the pinions is called the epi- 
cycloid, but very few understand the nature of this curve 
or the manner of tracing it. This knowledge may not 
be so important to them in respect to the workmanship as 
it would otherwise be, since the teeth of the wheels of 

68 the watchmaker's manual. 

the watches and clocks and of the leaves of their pinions 
are too small to permit them to give them precisely the 
form of an epicycloid. Yet this curve, traced on a large 
scale, will give them the idea of the form which these teeth 
should have, however small they may be, and they will 
seek to approach it even if they are not able to exactly 
obtain it. 

Experience has taught us that the most interesting class 
of clockmakers — the workmen who execute the machines 
designed to measure time — are the least instructed in the 
science which alone should serve as their guide. The most 
of the workmen who have consulted us on the part of 
which we now speak, after having read one, or, at the most, 
two pages of a book which we regarded as perfectly intel- 
ligible, have frankly told us that the language used by the 
author was above their comprehension. When they per- 
ceived the least proportion, the slightest formula, or the 
smallest sign, they closed the book and would no longer 
consult it. Yet, on taking up the author which they had 
thrown down, and simply reading the text to them, sup- 
pressing the formulas, they easily understood it. Adopting 
the hint, and availing ourselves of the works of the best 
authors on gearings, we hope that they will read with 

Of the Cycloid. — If along the straight line, C D (Fig. 7, 
PL III.), we turn the flat cylinder, A E, placing a small 
projecting point upon the point A of the circumference, and 
taking care that it does not glide off, this point will trace 
on the plane which bears the line, CD, a curve, A B E A ; 
this line is equal, therefore, to the circumference of the cylin- 
der, or of the generant circle, which has traced this curve, 
called cycloid, and which serves to find the form required 
for the teeth of a wheel or of a pinion, which works into 
the teeth of a straight rack. 



The curve which we have just shown, is described after 
the same method as that which we shall explain for the 

Of the Epicycloid. — When a flat cylinder, S (Fig. 8), or 
a circle, turns upon the outer circumference of another cir- 
cle, C M D, with the same conditions as in the cycloid, the 
curve, CED, which the point describes upon the plane, is 
called the epicycloid. If the same generant circle, A, instead 
of revolving over the outer, or convex circumference of the 
circle, moves in its inner circumference of Gr to H, the 
point describing E, which is a part of the point Gr, will 
describe another kind of epicycloid, Gr E H. The first of 
these two epicycloids is known as the outer epicycloid, and 
the second as the inner epicycloid. The first serves for 
the teeth of the wheels and pinions which are generally 
used, and whose teeth are placed upon the convex circum- 
ference of the wheels and the pinions ; the second, which is 
very rarely employed, serves for the teeth which are placed 
upon the inner circumference of the wheels. 

It would be a great mistake to suppose that the figure of 
the epicycloid should be employed, as a whole, to indicate 
the form of the teeth of the wheels. But a part of the 
beginning and a part of the end of the curve, according to 
the size of the tooth, is taken for this purpose. When this 
size is known it is marked upon the primitive circle, CMD, 
of the wheel, from the point C to F, for instance ; the other 
half, E D, of the curve is then moved in such a manner 
that the point D falls upon the point F ; these two demi- 
curves cross at the point H, and all beyond this point is 
useless, and is cut off; the rest, that is, C H F, gives the 
form of the tooth which projects beyond its primitive circle. 

Before describing the method of tracing a cycloid or an 
epicycloid by points, let us explain the meaning of the term, 
primitive circle. 


If we conceive a circle, J K (Fig. 9), which represents a 
wheel without teeth, and the small circle, N, a pinion with- 
out leaves, which meet at the point M, so that the wheel 
conducts the pinion by the simple contact of its circumfer- 
ence, in such a manner that the pinion may be always ob- 
liged to turn by the simple movement of the wheel, we then 
give the name of the primitive circle of the wheel to the 
circle, J M K, and that of the primitive circle of the pinion 
to the circle, 1ST. It is only necessary to add the teeth to 
these to give them the names of wheel and pinion, as we 
see in Figure 9. 

The cycloid or the epicycloid is traced by points in the 
following manner. The primitive circle, ABC, of the 
wheel is described (Fig. 10); above it is the circle E, 
whose diameter is equal to double the radius of the primi- 
tive circle of the pinion, and which touches the first circle 
at the point B, for instance. Twelve very small equal parts 
are then taken on the large circle from B to C, beginning 
at the point D, and insensibly diverging from a straight line. 
With the same opening of the compass, beginning at the 
point B and going towards D, as many points are marked 
on the small circle as had before been marked on the large 
one. The first radius, P B, is then traced, which should 
be prolonged until it meets the circumference of the generant 
circle, E. Through the centre of the great circle and 
through the six divisions (which are supposed indicated by 
the following figures, but are not traced on the figure to 
avoid confusion), 2, 4, 6, 8, 10, and 12, of the large circle, 
prolonged radii are traced like the radius, P B. Upon eaeh 
of the prolongations of these radii, and With the same open- 
ing of the compass which served to describe the circle E, 
the six demi-circumferences pounced in the figure are then 
described. The first of these circumferences has two divi- 
sions, and a point is marked on the second ; the second has 


four, and a second point is marked on it ; the third has six, 
always counting from the point of contact of the two circles; 
the next bears eight divisions ; this point is also marked, 
continuing thus unto the last. A curve is then passed 
through these six points, and a portion of an epicycloid is 
thus obtained, which is longer than is needed for the form 
of half of the tooth. 

As the other half of the tooth should be precisely the 
same but placed symmetrically, it is only necessary to copy 
this portion and place it on the other side, reversing the 
copy as the side-figure represents it, and suppressing all 
that exceeds the point where the two curves meet. This 
is done in the following manner : When the requisite size 
of the tooth is found, which is easily obtained by dividing 
it in such a manner that it shall have at least as much ful- 
ness as depression, we will suppose it equal at F Gr, we rest 
the curve upon F, and the other symmetrical part on Gr, 
and their junction indicates the length of the tooth beyond 
the primitive circle. The two parts, F H, and Gr I, are 
called the flanks of the tooth, and serve to lodge the curves 
of the leaves of the pinion. The points of the teeth of the 
wheels and the pinions are rounded ; the effect of the gear- 
ing is seen in Figure 9. 

All that we have just said in relation to the form of the 
teeth of the wheels, equally applies to the leaves of the 
pinions, whether they carry or are carried. The sole dif- 
ference consists in the pinion having more depression than 
fulness, and that in every case the half of the primitive 
radius of the piece worked, that is, of the wheel or pinion 
of which the form of teeth is to be found, should be taken 
for the radius of the generant circle. 

The epicycloid gives the best form for making a good 
gearing ; but this is not all that is needed to obtain a per- 
fect gearing. For this it is also necessary that when the 

72 the watchmaker's manual. 

two pieces work into each other, the tooth of the one which 
carries the other begins to touch its tooth in a right line, 
which is called the line of the centres, that is, the line pass- 
ing through both the centres of the pieces which work into 
each other. Pinions which have but few leaves never pos- 
sess this advantage. The learned Camus, who has expa- 
tiated at length on this subject, has proved that pinions 
having less than eleven leaves present this difficulty, and 
that it is greater in proportion as they are less numerous. 
One is, therefore, obliged to make them weaker, and to file 
the pinions very thin to prevent them from scotching. 
We recommend this important treatise to the notice of the 
reader ; it may be found in vol. ii. of his Mecanique Sta- 
tique, p. 355. The treatise of Delalande, on the best form 
to give to the teeth of wheels and to gearings, may also be 
read with profit in Traite d ' Horlogerie, p. 230, by Lepaute. 

We shall conclude this chapter with a judicious observa- 
tion of Camus, which confirms what we said in the begin- 
ning of it. 

"1. Although the rules that have just been given for 
the formation of the teeth of wheels and of the leaves of 
pinions can only be practised when the teeth are at least 
five lines in width and five lines in length, reckoning from 
the primitive circle, they will not be useless to artists who 
make finer teeth than these, because having the figure of a 
large tooth which they wish to copy in miniature before 
their eyes, it will be more easily imitated. 

" 2. As one cannot hope to form the teeth with all the 
equality and precision which are necessary in order that 
the primitive circumferences of the wheel and the pinion 
shall always turn with the same velocity ; as some teeth 
will not conduct the leaves which they should impel as far 
after the line of the centres as is needed, and as this may 
result in the propping of the leaves against the flanks of 


the teeth, the artists may prevent this difficulty by making 
the primitive diameter of the wheel a little larger than it 
should be, relatively to the pinion. 

" 3. By means of this increase of the diameter of the 
wheel, which should be proportionate to the defects which 
may be feared in the teeth, the tooth which follows the one 
that pushes the leaf after the line of the centres, takes the 
next one a little more slowly ; and, when the preceding 
tooth has impelled the leaf after the line of the centres as far 
as it can uniformly do, the wheel takes a little more velocity 
than it communicates to the pinion. This is a fault ; yet 
this fault is less to be feared than are the abutments to 
which they would otherwise be exposed. 

"4. It is evident that what has just been said respect- 
ing the increase of the diameter of the wheel beyond that 
which is necessary uniformly to conduct the pinion, sup- 
poses that the wheel will impel the pinion, when the 
pinion should carry the wheel. It is clear, therefore, that, 
in order to shun the abutments, the primitive diameter of 
the pinion should be a little larger than is necessary to 
conduct the wheel uniformly." 

However a watchmaker may have reflected on the gear- 
ing of the crown wheel with the pinion of the escapement 
wheel, he must agree that this gearing is bad and very 
defective, and that the system long since adopted in Geneva 
and Switzerland, of passing the axle of the escapement 
wheel by the side of the axle of the crown-wheel, tends to 
render it still more imperfect. The pinion that gears into 
the crown-wheel can only form a better gearing by taking 
a conical form, according to the rules prescribed by Camus. 



Under the name of escapement is designated the action 
of the last wheel of the movement upon the balance. By 
this action, the balance suspends the movement of the 
wheel during its own vibration, after which it disengages 
the wheel to permit the passage of one of its teeth, which, 
in its progressive movement, restores to the balance the 
force that it had lost during its vibration, or its preceding 
oscillation. This invention dates far back in the history 
of the horological science ; the name of its author is un- 

Escapements for Watches. 

Two things should be considered in every escapement — 
1st, the lifting of the escapement ; 2d, the arc of vibration 
of the balance. 

1st. By the lifting of the escapement, we mean the num- 
ber of degrees which each tooth of the wheel causes the 
balance to pass over, whatever escapement may be em- 
ployed, from the moment in which it begins to act upon 
the escapement-piece until it quits it. The arc described 
between these two limits is called, the lifting of the escape- 

2d. By the arc of vibration, we mean the total arc de- 
scribed by the balance when impelled by the motive force 


which is transmitted to it by the teeth of the wheel ; whence 
it follows that the greater the motive power, the more forci- 
ble will be the action of the tooth which transmits it to the 
escapement-piece by its inclined planes, or by its pallets, 
impelling the balance in such a manner as to cause it to 
pass over larger arcs of vibration; this is reversed when 
the motive power is diminished. We may therefore con- 
clude that in these two cases the vibrations cannot be 
isochronal, since this word supposes that they have the same 
extent and that they are of equal duration. This simple 
reasoning will not require the support of experience to 
prove the error of those watchmakers who persist in main- 
taining that the dead-beat escapements correct the inequality 
of the motive force. 

I. — Balance- Wheel Escapement. 

This escapement, which is the oldest known, is the most 
simple and easil}' executed of any, and is found in the most 
ordinary watches; yet, as Ferdinand Berthoud has re- 
marked, when one wishes to make it with all the art of 
which it is susceptible, it becomes very difficult, and few 
workmen are skilful enough to succeed in it. It has a 
crown-wheel, with an uneven number of teeth. 

The balance-wheel escapement is recoil ; that is, when a 
tooth of the wheel has given the impulse to the spiral spring, 
the latter, after the lifting of the escapement, presents to the 
following tooth an inclined plane during its arc of vibra- 
tion, and causes the wheel to retrograde. But this escape- 
ment is so well known that it is unnecessary to describe it. 

II. — Cylinder Escapement Plate III. 
The cylinder escapement was invented in 1720, by 

76 the watchmaker's manual. 

Graham, a skilful watchmaker of London ; it was not 
known in France, however, until the year 172-1. It 
received its name from the fact that the escapement-piece is 
a steel cylinder, upon which the balance is riveted. 

The cylinder-wheel is of a different form from the other 
wheels ; it is canting, like a crown-wheel, but differs from 
it, especially in the form of its teeth. It is hollowed like a 
crown-wheel, and, when its height is fixed, a flange, suffi- 
ciently projecting to form the inclined planes which the 
wheel carries, is preserved on its exterior, on the top of its 
upper surface. When the wheel is thus prepared, a num- 
ber of teeth double to that which is required, is cut with a 
thin cutting file; these may be even or uneven, at will. 
The teeth are alternately suppressed, and a circular form is 
then given to this space by means of a cutter, so that the 
inclined plane remains supported by a small column (as in 
Figure 11, which shows it in elevation, and in Figure 12, 
which shows it flatwise on a larger scale). 

When the wheel is cut, it gives the outer and inner 
diameter of the cylinder. The length of each inclined 
plane gives the interior diameter, which is made a little 
larger in order to avoid the friction. The exterior diame- 
ter is equal to a cut-off tooth, plus twice the thickness of 
the cutting file used in cutting the wheel, so that the cylin- 
der is of the same thickness as the cutter. 

The cylinder in the part in which the escapement is 
made, is not notched in proportion to its diameter, but a 
little less ; the projection which forms the inclined plane 
beyond the circle of the wheel which passes through the 
point of the inclined plane determines the size of the notch. 
When the tooth b (Fig. 12) is in the interior of the cylinder, 
the inclined plane, a c, forms the diameter of the cylinder. 

The cylinder is generally made of tempered and highly 
polished steel ; the two edges, m and n, upon which the 


escapement is made, are of different forms ; the edge, n, by 
which the tooth enters the cylinder, is rounded, the edge, m, 
by which it goes out, is on an inclined plane. We set at e 
(Fig. 13) another and much larger notch at the bottom of 
the cylinder ; this notch is only designed to permit the 
balance to vibrate freely without letting the cylinder touch 
the lower part of the wheel, as this would produce irregu- 
larity in the machine by diminishing the arcs of vibration. 

The cylinder being finished as we have just described, 
brass cylinders or stoppers are adjusted about its two ends. 
Fig. 14 shows the upper stopper, and Fig. 15 the lower one. 
A rod of tempered steel is driven into each of these stop- 
pers, at the extremities of which pivots are formed. These 
stoppers are now generally made of steel, of a single piece 
with the rod which turns them. The upper stopper A, 
carries at b the balance which is riveted there ; the part c is 
designed to receive the ferrule of the spiral spring ; the part 
d enters exactly into the top of the cylinder. When all is 
thus prepared, both for this and for the lower stopper f, the 
projecting parts in the interior are cut off on the lathe and 
the two stoppers are put in place ; these should be so well 
adjusted as to be solidly fastened by a slight blow of the 
hammer. Fig. 16 shows the cylinder mounted. 

The cylinder should be notched in such a manner that 
the lifting of the escapement may be twenty degrees at each 
impulse. Fig. 12, designed upon a large scale, will clearly 
show the arrangement of the wheel and the cylinder in the 
different times of the escapement. The tooth B, which rested 
upon the convex surface of the cylinder, begins to enter the 
cylinder; but the point /cannot reach the point a until the 
cylinder shall have made a circular movement on its pivots, 
determined by the projection of the inclined plane of the 
tooth B, and consequently until the edge, «, shall have 
reached h. Then the tooth B passes and takes the position 

78 the watchmaker's manual. 

0, its point resting upon the concave surface of the cylin- 
der, where it remains until the balance, having finished its 
arc of vibration, brings the cylinder back to the point where 
the tooth D presents itself. This process is the same as the 
preceding one, the point g cannot entirely depart until the 
inclined plane shall have caused the cylinder to retrograde 
in such a manner that its edge r may reach s ; the following- 
tooth, E, then comes to rest upon the convex surface of the 
cylinder, and the effect which we have before described for 
the tooth B will be produced when the balance shall have 
brought back the cylinder to the point at which we see it in 
B. The importance is obvious of having all the parts of 
the inclined planes of the wheel uniform and equal. We 
give a description in a following chapter of new tools de- 
signed to obtain this perfection. 

The difficulty that has been experienced in finding brass 
pure enough for the wheels of the cylinder has caused the 
adoption of wheels of cast and tempered steel in carefully 
executed watches ; the cylinder is a jewel, or at least the 
edge on which the escapement is made. This stone is fixed 
by gum-lac into a steel apparatus which the workmen call 
mcmivelle, and which serves to connect the upper part of 
the cylinder with its lower part. 

Figure 17 gives an idea of this ferrule. We see that 
it is formed of three cylindrical parts, a, 5, and c, supported at 
the proper distance by the two columns df. To make this 
a round piece of steel is taken which is pierced at both ends 
with a smaller hole than is required for the cylinder. When 
it has been turned round, in the form indicated in the figure, 
it is notched, leaving only the two columns d and /; half 
of the cylindrical part b is removed, and a grooving whose 
two extremities are seen opposite &, is made in the remain- 
ing half of the cylinder in order to lodge there the demi- 
cylinder of stone, called the pallet — this finishes the fer- 


rule, which is then polished. The upper cylinder or stop- 
per is adjusted in the cylindrical part a, and the lower stop- 
per in the cylinder c, in the manner which we have described 
for the common steel cylinders. 

Breguet changed almost entirely the form of the two 
essential pieces constituting the cylinder escapement — the 
wheel and the cylinder. 

The wheel (Fig. 18) is simply a crown wheel, the crown 
of which is a part of a truncated cone whose larger base 
exceeds the smaller one in an equal quantity to that pre- 
sented in an ordinary wheel by the projection forming the 
inclined plane. Double the number of teeth required are 
then cut in the wheel with a thin cutting-file, and an alternate 
tooth is suppressed ; the front of each tooth is then filed in 
an inclined plane from the side where it moves forward 
nearly to the end of the tooth, leaving but a small space 
flat by which the repose and lifting are made. The back 
of the tooth is also filed in an inclined plane, but less than is 
the front of it. 

Figure 19 indicates Breguet's form of mounting. The 
demi-cylinder a bears the grooving d d to receive the tuile 
or the demi-cylinder of stone. The part c is properly the 
mounting, with a sort of column which connects the two 
parts a and b. The ferrule b is pierced with a hole large 
enough to receive the axle of the cylinder, to the ends of 
which the pivots are formed. These pivots, which are as 
fine as possible, are first turned in a cylindrical form, and 
then depressed in the middle of their length. This con- 
struction tends to diminish the friction, since the pivot only 
rubs by the two extremities of its length, while the depres- 
sion in the middle serves to retain the oil and lessen the 
friction. Breguet did not round his pivots as had been 
done before ; his pivots are flat beneath while the edges are 
slightly rounded. 


By this improvement lie got rid of variations caused by 
the position of the watch. Without his improvement, if 
the watch was lying flat, the pivot working only upon 
a rounded point moved with greater freedom than if 
it was hanging, when it worked in the length of the 

Figure 20 shows the cylinder mounted with a fragment, 
n, of the balance. We see there the pallet, m, and the two 
pivots h and g. The inner pivot, g, is received into the 
bridge, r, which is seen in plane at a, and in profile at b 
(Fig. 21). This bridge is supported by the slide. This 
escapement, whose perfect execution demands a practised 
and skilful workman, has never before been fully described. 

III. — The Duplex ^Escapement. PL III. 

This is a dead-beat escapement, and is much more easily 
executed than the cylinder escapement. The escapement- 
wheel is flat. 

Figure 22 presents but a fragment of it at A ; its teeth 
are cut as in a cog or star- wheel, but are very long and are 
placed apart. This distance from one tooth to another is 
necessary in order to drive a pin into the crown-wheel per- 
pendicular to its surface in the midst of this space. These 
pins are planted in a circle concentric to this wheel, so that 
they are always at the same distance from the axle of the 
balance. These pins, however, do not seem to be used at 
present ; but a crown is reserved on the plane of the wheel 
as in the crown-wheel, and this crown is divided by the 
wheel-cutter in the same manner as the teeth of the wheel, 
so that they may be equi-distant. We have examined a 
construction of this kind in an English watch which renders 
the wheel lighter, and which will serve as the model to our 


The axle of the balance carries a roller, B, which is 
usually a jewel, having a small notch, a, designed to receive 
the points of the long star-teeth, CDE. A large arm, Gr, 
is carried above this roller by the same axle of the balance, 
and reaches as far as the pins, H I J, formed by the crown- 
wheel which forms one with the star- wheel. This escape- 
ment works in the following manner. It must first be 
understood that the wheel moves in the direction indicated 
by the arrow b. The figure shows the tooth, D, working 
in the notch, a, of the roller, B ; at the same time the arm, 
Gr, is lifted up by the pin, I, which pushes it backwards and 
communicates the vibration to the balance, armed with its 
spiral-spring ; the tooth, D, immediately leaves the notch, a, 
and the tooth, C, comes to rest upon the roller, B, at the 
point k ; the balance completes its vibration and the spiral- 
spring brings it back to the point where the small notch, a, 
presents itself before this tooth when it enters it. At the 
same time the lift, Gr, presents itself before the pin, H, which 
pushes the balance in acting upon the lift, Gr, as in the first 
case. The lifting here is sixty degrees. "We see that this 
escapement is dead-beat, that the repose is made on the 
roller, B, on the side of &, and that the balance receives but 
one impulse in two vibrations. 

"We also see that this escapement which, at first sight, 
seems very easily executed, presents difficulties which can 
only be surmounted by a skilful artisan. It is, however, 
less difficult of execution than the cylinder escapement of 

IV. — Escapements of M. Pons de Paul. 

M. Pons, a skilful clockmaker, who is at the head of the 
clockmaking manufactory of St. Nicholas d'Aliermont, has 
described his different escapements in the Bulletin de \a 


82 the watchmaker's manual. 

Societe cC Encouragement, vol. xxvii. p. 421, which descrip- 
tions and figures we shall literally transcribe. 

1st. — Hooh Escapement. 

" Figure 1, PL IV, represents the escapement- wheel in 
plane ; this wheel carries ninety-two pins. Figure 2 shows 
the place of the escapement piece ;* we see this piece in per- 
spective in Figure 3. In Figure 4 it is mounted upon the 
axle of the balance, Y, which carries the spiral-spring V. 
The letters a and b (Fig. 1) indicate the successive positions 
of the escapement at the time of its connexion with the pins 
of the wheel. 

" Effect. — The piece, a (Fig. 1), represents the escapement 
in its state of rest, a pin of the wheel is in contact interiorly 
with the piece a; the balance turning from right to left, 
this piece will turn around the pin ; the balance returning 
from left to right, the pin will glide along the lift, o, and 
will make it pass over an arc of thirty-five degrees. As 
soon as it escapes, a third pin comes to place itself on c ; in 
this position a pin will be between the one which escapes 
and the one that comes in contact as we see in b ; the 
balance returning from right to left, the pin will glide along 
the curve, c, giving an arc equal to the first. At the mo- 
ment in which this last pin escapes, the one placed in the 
interior of the escapement-piece comes in contact with this 
piece as in a, to recommence the effect which we have just 

" We must remark that the lift of this escapement can 
always be alike, because knowing the extent and the lifting, 
c, we can incline or elevate the lift, o, at pleasure to cause it 
to pass over an equal arc. 

* This piece is of the hardest tempered steel, and is fixed upon a support- 
socket forcibly adjusted upon the axle of the balance. 


" This escapement is well adapted to watches in which 
slow vibrations are required." 

2d. — Spiral Escapement. 

"Figure 5 represents the escapement- wheel in plane; 
this wheel carries twelve pins. Figure 6 is a roller with a 
notch, whose edges are rounded to facilitate the disengage- 
ment of the pins of the wheel. Figure 7 shows the plane of 
the escapement-piece ; we see this piece and the roller in 
perspective in figure 8. In the Figure 4 these two pieces 
are mounted upon the axle of the balance Y, upon which 
is fixed the spiral-spring V. The letters, abed (Fig. 5), 
indicate the successive positions which the escapement-piece 
takes at the time of its connexion with the pins. 

" Effect — The piece, &, represents the escapement in its 
state of rest ; the pin is placed in the notch of the roller, 
and the spiral spring of the balance has no tension. The 
balance turning from left to right, the pin leaves the notch 
of the roller and places itself on the lift, o, as indicated in 
the piece, c. The action of the wheel continuing, the pin 
glides along, o, and comes in the position of the piece, d; in 
this movement the lift will have passed over an arc of 
ninety degrees. At the moment when the pin escapes, the 
following one places itself upon the lift, f, and the balance 
returning from right to left, the pin glides along this lift 
until it escapes and comes upon the roller in the position, a. 

" In this movement the lift will have passed over the 
same arc of ninety degrees in a contrary direction ; and the 
balance returning from left to right, the pin will return to 
the position, 6, in order to recommence the movement. 

3d. — Gearing Escapement. 
"Figure 9 represents the escapement- wheels in plane; 

84 the watchmaker's manual. 

the wheel, a, carries eight pins, and the wheel, b, sixteen 
teeth. Figure 6 shows the plane of the piece which is 
connected with the pins of the wheel, a, and on which the 
repose is made. Figure 10 represents that of the piece 
bearing the two impulse-pallets that work into the teeth of 
the wheel, b. These pieces are seen in perspective in Fi- 
gures 11 and 12. In Figure 13 these pieces are mounted 
upon the axle of the balance, Y, upon which the spiral- 
spring, Y, is fixed. The letters c, c?, e, yj g (Fig. 9) indicate 
the successive positions which the escapement takes at the 
time of the connexion of the pins and the teeth, with the 
pieces which compose it. 

" Effect. — The position, c, shows the escapement in its 
state of repose ; the pin is placed in the notch of the re- 
pose-piece and the spiral- spring has no tension. The ba- 
lance turning from left to right, the pin leaves the notch, 
mounts upon the small curve opposite, and escapes as soon 
as the first of the two pallets comes in contact with one of 
the teeth of the wheel, b, as is represented in d. The 
second pallet presents itself beneath the following wheel 
at the moment in which the two first are upon the line of 
the centres, as in the position, e. The wheel continuing its 
movement, they come as inf, and, finally, as in g. In this 
movement, the escapement-piece will have passed over an 
arc of seventy-five degrees. At the moment in which the 
second pallet escapes, one of the pins of the wheel, a, places 
itself upon the large curve of the piece of repose, as in a, 
and the balance returning from right to left, this pin glides 
along this curve, enters into the notch, and mounts upon 
the small curve opposite by the impulse which it has re- 
ceived ; it then takes again the position, c, to recommence 
the same movement. In gliding along the large curve of 
the piece of repose, the lift passes over an arc equal to the 


4th. — Inclined-plane Escapement. 

"Figure 13 (bis) represents the escapement- wheels in plane ; 
the wheel, a, carries twelve pins, the wheel, b, twelve im- 
pulse-pallets on an inclined plane. Figure 14 shows the 
plane of the piece that connects with the teeth of the wheel, 
a, and upon which the dead-beat is made. Figure 15 that 
of the impulse -pallet on an inclined plane, and which, cor- 
responds with those of the teeth of the wheel, b. We see 
this in perspective in Figure 16. Figure 13 shows these 
pieces mounted upon the axle of the balance, Y, upon which 
is fixed the spiral-spring, Y. The letters, /*, i, k, I, indicate 
the successive positions of the escapement. 

" .Effect. — The position, A, represents the escapement in 
its state of repose ; the pin of the wheel, a, rests upon the 
circumference of the repose-piece, and the spiral-spring has 
no tension. The balance turns from right to left, the pin 
glides along the part, going spirally towards the centre of 
motion ; it leaves the notch and mounts upon the small 
curve opposite by the impulse that it has received, which 
gives a slight recoil to the wheel. In this movement, the 
lift will have passed over an arc of fifty degrees. The 
balance returning from left to right, the pin escapes as soon 
as the upper extremity of one of the teeth of the wheel, b, 
comes in contact with the impulse-pallet, as is indicated in 
the position, i ; the two planes are thrown successively in 
contact and come upon the line of the centres, as in h, and, 
finally, in the position, I. In this movement, the lift will 
have passed over an arc equal to that of the first. At the 
moment in which the contact of the arc ceases, the pin of 
the wheel, a, places itself upon the repose-piece, as in /, 
and resumes the position, h, in order to recommence the 

86 the watchmaker's manual. 

We see that the first two of these four escapements bear 
some analogy to the Duplex, but they more nearly resemble 
the simple hook-escapement, which has been abandoned on 
account of its difficulty of execution. We fear that they 
present the same objection, although they seem very inge- 
niously conceived. 

Y. — Detached Escapements. 

In the dead-beat escapements of which we have just 
spoken, the movement of the wheel is suspended during 
the vibration of the balance, but this suspension is caused 
by the wheel itself, which, during the whole time of vibra- 
tion, rests one of its teeth upon a cylindrical part, carried 
by the axle of the balance. It is evident that the force 
with which the wheel is impelled produces a friction upon 
the axle of the balance which, however slight it may be, is 
an obstacle to the free movement of the spiral-spring. The 
dead-beat escapement requires oil, and thus induces variable 
resistances, which are very pernicious. 

Berthoud seems to have had the first idea of detached 
escapements in 1754. He gives the following explanation 
in his Histoire, etc., vol. ii. p. 23 : — 

" The defects which I have remarked in the ordinary 
dead-beat escapement have caused me to seek the means 
of remedying these evils. For this purpose I have combined 
the escapement in such a manner that the spiral-spring can 
freely accomplish its vibration as soon as the wheel has 
given its impulse, and that during this time the effort 
of action of the train is not suspended, as in the dead- 
beat escapements, by the spiral-spring itself, but by a de- 
tent which the balance disengages in an indivisible time ; 
so that the regulator does not thus meet with any resistance 
or friction except that of disengaging the detent, which 


suspends the effect of the wheel, while the balance oscil- 
lates freely. 

In this escapement the balance makes two vibrations, 
while but a single tooth of the wheel escapes at a time ; 
that is, the balance goes and returns, and on its return at 
the second vibration, the wheel, in escaping, restores to the 
regulator in one vibration the force it had lost in two. 
Thus the action of the wheel remains suspended by a detent 
during the whole of one vibration, and the greater part of 
the second, so that the balance oscillates freely during this 

We shall not attempt to describe all the detached escape- 
ments which have been invented, as this would far exceed 
our proposed limits, but shall confine ourselves to a descrip- 
tion of one which is now successfully used, both for watches 
and clocks, and also for chronometers. 

YI. — Arnold detached Escapement. 

Plate IY., Fig. 17, presents all the details of this escape- 
ment. The cylindrical piece, A, is notched at g, as is 
shown in the figure. This piece, A, is carried fixedly by 
the axle of the balance. This axle also carries a tooth or 
finger, a ; these two pieces, which are invariably fastened 
to the axle of the balance, move with it. Upon the pillar- 
plate of the movement the spring, 6, c, is fastened by a screw 
and two chicks ; this bears three arms, d 1 f, 7c. The first, d, 
serves to suspend the movement of the escapement- wheel, 
B, and to permit but one tooth of the wheel to pass succes- 
sively when forced by the spiral-spring. 

The second arm, f, which is fixed like the first upon the 
spring, b, c, serves to determine the length of the small 
spring, % h, which is fastened in this arm, in the same 
manner as is the spiral-spring in its screw. This small 

88 the watchmaker's manual. 

spring readies nearly to the axle of the balance, so that the 
little finger, a, cannot turn without causing it to vibrate. 
The third arm, &, receives into a small notch the little 
spring, i, /?, whose use we shall explain. 

When the balance turns in the direction pointed by the 
arrow, it draws along the cylindrical piece, A, and the little 
finger, a. The latter causes the small spring, ?', to bend ; 
this yields easily on account of its great flexibility, and per- 
mits the passage of the finger, a. All this is effected without 
any movement of the escapement-wheel, B, whereby to cause 
the cylindrical piece, A, to reach any tooth. But when the 
balance returns backward, after this first vibration, the finger, 
a, seizes the top of the spring, i ) and causes it to rest upon the 
arm, &, which then becomes the centre of motion of the 
spring, b, c. This arm, &, is placed as near as possible to the 
cylindrical piece, A ; the small spring, i, then becomes strong 
enough to cause the spring b c to yield, which, in rising, 
draws along the arm, d, and disengages the tooth of the 
escapement wheel, B. This spring returns to its first posi- 
tion, and the arm, d, arrests the following tooth. During 
this movement, the tooth, m, comes to rest upon the arm c?, 
and the tooth n, which advances at the same time, encounters 
the lift g, and restores the force to the spiral-spring, which 
it has lost in the two vibrations. 

Breguet adopted this construction for chronometers beat- 
ing but five vibrations in two seconds. This escapement 
makes an audible sound, so that it is easy to count the 
vibrations ; these are slow but possess great regularity. 

VII. — Detached Escapement of L. Seb. Le Norman. 

This was invented in 1784, and operated well. It was 
executed in a small clock belonging to the Bishop of 
Montauban, instead of an anchor escapement. 


Figure 18, PL IV., shows the wheel in place. This wheel 
has two crowns; that is, it has a crown like that of an 
ordinary crown-wheel upon each of its surfaces. The wheel 
is about half-a-line in thickness, and the thickness of each 
of its crowns does not 'exceed half-a-line. These crowns 
form the inclined planes which each tooth of the wheel 
bears alternately upon one of its surfaces. The wheel 
always has an even number of teeth, as each tooth forms the 
lift, sometimes on one surface and sometimes on the other. 

This wheel is easily cut upon the tool for cutting the 
balance-wheels, and is finished on the same tool, including 
the inclined planes. It is first divided into equal parts by 
an ordinary cutting- file of half a line in thickness ; then one 
tooth is alternately taken from each side by a flat cutter, 
whose thickness should equal the length of one tooth, and 
finally the width of the remaining tooth is cut with the 
inclined cutters by the diagonal of the rectangle, which each 
of them presents in face. The teeth then appear as shown 
in Figure 19, the wheel being in profile. 

The escapement-piece (Fig. 20) here is nearly of the 
natural size ; it is fixed in a (Fig. 18) in such a manner that 
it can only turn with this axle which is placed vertically 
and in a plane parallel to the plane of the wheel. A fork, 
bj is fixed with a socket upon the same axle ; this should 
be opposite a tooth or finger, c, fixed in the same manner 
upon the axle of the balance d. The balance, f, is placed 
horizontally above the frame, and in a plane perpendicular 
to the plane of the pillar-plates. Above it is placed the 
spiral-spring, S. Figure 21 shows the form of the fork, Z>, 
fixed upon the axle of the escapement-piece (Fig. 18) ; and 
Figure 22 shows the tooth, c, carried by the axle of the 
balance, c?, and which works into the fork, b. 

It is evident that when the spiral-spring brings back the 
tooth, c, between the teeth of the fork, 6, the balance will 


force the escapement-piece, a, to make a rotary movement; it 
then presents its notch to the inclined plane of the tooth which, 
in escaping, restores to the balance the force which it had lost 
during the preceding vibration, through the medium of the 
pin and the tooth, causing it to describe a lifting of forty de- 
grees. The following tooth then comes to rest on the escape- 
ment-piece, a, until the balance disengages this piece on its re- 
turn and lets a second tooth escape, which also causes a lifting 
of forty degrees, and so on. The essential point in this easily 
executed escapement consists in placing the upper surface of 
the escapement-piece, a, in the plane of the horizontal dia- 
meter of the wheel. This escapement-piece should be some- 
what thinner than the cutting-file used in cutting the wheel. 
We have suppressed in this figure the bridges which 
support the escapement-piece and the balance, in order to 
render the design less complicated. 

"VTU. — Escapements for Pendulum and Belfry- Clocks. 

Independently of the escapement which we have just 
described, and which is suited to those apartment-clocks in 
which a pendulum is not desired, this escapement procures 
the advantage of directly beating the dead-seconds, what- 
ever may be the height required for the case which encloses 
the movement. A great number of escapements applicable 
to this kind of clocks exist, but we shall confine ourselves 
to the description of those which are acknowledged to be 
the best, and which are most in use, such as, 1st, the anchor- 
escapement, which is used in nearly all the small apart- 
ment or mantel-clocks; 2d, the Graham-escapement, used 
in many regulators, and in belfry -clocks ; 3d, the pin- 
escapement of Lepaute, which is unquestionably an excel- 
lent one, and which is now much in use for regulators and 


§ IX. — Anchor Escapement for Belfry -Clocks. 

This escapement was invented by an English clockmaker, 
whose name is not positively known; some attribute it 
to Thomas Mudge, and others to Clement. It is called 
"anchor escapement," because the two branches that com- 
pose it bear some resemblance to the flukes of an anchor. 
It is represented in Fig. 23, PL IY. We are obliged to 
enter into some details in respect to this escapement, as well 
as to the one improved by Graham, in order to point out 
two errors respecting the nature and the uses of these 
escapements which have been propagated within a few 

The first of these errors consists in the assertion that this 
escapement is recoiling in mantel-clocks. It was given by 
the inventor as a dead-beat escapement, and Fig. 23, PL 
IV., which represents it, proves this incontestibly, as the 
curves d c, and m n, upon which the two dead-beats are 
made, are arcs of circles which have their centre at a. 

We shall presently see that Berthoud has expressly de- 
clared this, in giving rules by which to make them recoiling 
in small clocks, with the view of rendering the vibrations 
isochronal. In 1763 he pointed out a method of rendering 
the anchor escapement, invented in 1681 by Clement, a 
London clockmaker, a recoil. This had been therefore ex- 
clusively a dead-beat escapement for eighty-three years, 
before any one had succeeded in giving it the best form 
for recoil in order to make it isochronal. Since the dis- 
covery of Berthoud, we have seen many of these recoil 
escapements, although very few are isochronal, because 
most workmen neither know how nor care to practise the 
rules which he prescribed. The construction of this escape- 
ment as dead-beat, has not, however, been abandoned, and 

92 the watchmaker's manual. 

it is incorrect to assert that this escapement is recoiling 
by nature when it was only made so by art. 

The second error consists in maintaining that this escape- 
ment, and even that of Graham, permits two teeth to pass 
at each oscillation. This assertion is too absurd to merit a 
serious refutation. 

We will only say to those who affirm this, that if they 
guide the pendulum of a clock with their hand, and count 
the number of strokes which the wheel when impelled by 
the motive power beats at each vibration, they will count 
but one. Now each tooth gives a stroke in passing. 

Berthoud gives the following rules for making the 
anchor escapement recoiling : — 

" The distance from the centre, a, of the escapement- 
anchor to the centre, A (Fig. 23), of the wheel, depends on 
the arc over which the pendulum is to pass. If it is to 
describe a large one, ten degrees for instance, the centre, a, 
must be placed near the wheel. Care must be taken in all 
cases that the opening of the compass which serves to trace 
the repose shall be such that in drawing from the point, w, 
a line passing to the centre, a, of the anchor, and letting fall 
from the extremity, n, a line passing to the centre of the 
wheel, the line shall be perpendicular to n, a. 

"Julien Leroi, and Saurin, in 1720, and Enderlin in 
1721, employed themselves in researches by which to deter- 
mine the curvature which should be given to the faces of 
the anchor to render the oscillations of the pendulum iso- 
chronal. Berthoud succeeded in ascertaining the true form 
required for the anchor, and resolved the problem given 
by preceding clock-makers in a satisfactory manner. 

" The isochronal escapement which we propose to describe 
is not a dead-beat, neither is it as much recoiling as is the 
anchor of Enderlin ; but its recoil is mean between the 
dead-beat of the first and the recoil of the second." 


This escapement for rendering the oscillations isochronal, 
is shown in PI. IV., Fig. 24 ; we have represented it on a 
large scale, that the peculiarities of its construction may be 
more easily distinguished and understood, after which it 
will be easy to trace it in miniature by the prescribed 

To trace the escapement-anchor, we take a well -tem- 
pered and polished thin plate of brass, eight centimetres 
square, which is called the escapement-caliber, and pierce 
a hole towards one of the edges of the plate, at a sufficient 
distance to be able to trace there the circumference of the 
wheel. We adjust the small rod of the pinion of the bot- 
tom of the wheel into this hole, in such a manner that the 
whole wheel is laid upon the plate, and then trace a circle, 
of the exact size of the wheel, with a watchmaker's com- 

With, the same compass, we take upon the pillar-plate 
the distance from the centre of the escapement- wheel to the 
hole of the pivot of the anchor-rod ; we carry this distance 
on the brass plate, and trace from the centre, B, of the 
wheel, the portion of the circle b, c; we pierce a small hole 
of the size of the pivot of the anchor-rod at a; this hole 
represents the centre of the anchor. From this centre we 
draw the line a, b, which may be a tangent of the circum- 
ference, 6, c, of the wheel ; if through the line of touch, b, 
we draw the radius B, b, it will be perpendicular to b, a, as is 
demonstrated in geometry ; and, according to the principles 
of mechanics, the action of the teeth, of the wheels should 
be at the point b, on the anchor ; thus, a, 6, is the length 
which must be given to the arm of the anchor, in order 
that the wheel may act upon it in the manner best suited 
to the movement. 

We place the wheel upon the brass plate ; we then place 
one point of the compass upon the hole of the anchor, and 

94 the watchmaker's manual. 

with, the opening of the compass, a, b, we make the other 
point agree with that of a tooth, 6, of the wheel taken in 
front. For this, we turn the wheel as required, then hold- 
ing it stationary while we carry the point of the compass 
to the other side to see if it appears at the back of the point 
of a tooth, c ;* if this is not effected, we change the opening 
of the compass until it passes by the teeth nearest the points 
of contact, c, b, and we find the portions of a circle, 6, t, c, p, 
which represent the two faces of the flukes of the anchor. 

To find the two other faces, the opening of the compass 
must be changed, so that the teeth having passed over half 
their interval, they pass through a second part of a circle ; 
but as this can either be done by opening the compass far- 
ther, or by closing it half the interval of a tooth, the opening 
should be chosen which will make the length of the lines 
to differ least from the points of contact, from which they 
should diverge as little as possible. We then find the two 
other faces of the anchor, d : s, e, g, which we place within in 
order to diminish the space which the anchor passes over, 
and consequently, its friction. We will thus have the four 
faces of the two arms placed in such a manner as to permit 
the teeth to escape alternately, in proportion as these flukes 
penetrate and depart from the wheel by the movement of 
the pendulum. 

To regulate the length of the flukes of the anchor, we 
divide the extent of the lifting required for the escapement, 
which we fix at five degrees on each side or thereabouts. 

To mark this lifting of the escapement exactly, we must 
have a semicircle graduated in degrees, the centre of which 
must accord with the hole of the anchor-pivot, which is 
pierced in the escapement-caliber ; we prolong the line a, Z>, 

* The part of the circle, c, p, should pass behind the tooth, c, so that the 
angle, c, of the fluke, c, e, may not prop against it as the tooth, b, draws away 
the arm, b, t, and as the latter inserts itself between the teeth of the wheel. 


as far as/ the edge of the graduated semicirele, and turn the 
instrument until one of its divisions corresponds with the line 
b, f, marking within a point, g, five degrees distant from the 
other. Through this point we draw a line passing through 
the centre of the anchor,, and mark, at d, the quantity to be 
given the fluke, so that the wheel turning in an inclined 
plane, the anchor will describe five degrees. To find this 
inclined plane, we trace the lines d, 6, which should pass 
through the points d ) and 6, in which the right lines, a,/, 
a, #, which measure the angles, g, a. f, cut the portions of 
the circle d, s, b, t; we then have the fluke, d } 5, traced. 

We proceed in the same manner to obtain the other 
fluke of the anchor; we obtain the angle, i, a, A, of five 
degrees, which determines the direction of the inclined 
plane, c, e. By this method, the total lifting of the escape- 
ment will be ten degrees. 

The escapement thus traced will be dead-beat, as it is 
formed by the arcs of a circle concentric to a ; but as such 
an escapement will not correct the inequalities of the mo- 
tive power, the curves, b, I, e, &, should be traced upon the 
anchor ; this will cause the wheel to retrograde as the flukes 
become connected with the teeth by the increase of the 
motive power. 

To trace the curves in such a manner as to give the 
recoil suited to render the oscillations isochronal, the fol- 
lowing dimensions should be employed : take with a com- 
pass the interval b, m, which separates the arcs of the 
circle 6, t, d, s ; carry it three times over the arc of the 
circle, starting from the angle b. of the inclined plane, and 
mark the point 4 of the third division with the same open- 
ing of the compass. From this point with the radius «, b, 
describe a small arc of a circle towards n ; and from the 
point b, with the same opening of the compass, describe a 
small arc towards w, which cuts the first at the point n. 

96 the watchmaker's manual. 

This point, n, will be the centre from which, with the same 
radius, a, b, to describe the arc £, 4, b, which will give the 
desired curve. 

To trace the other curve in the interior of the fluke c, e, 
take the same thickness, e, w, of this fluke ; start from the 
angle e, of the inclined plane, and carry it three times upon 
the portion of a circle, e, q, of the third division ; then mark 
the point 4, with the same opening of the compass upon 
the direction of a line, 3, a, as has been done on the other 
side. We find the point o, in the same manner as we found 
the point n, by taking an opening of the compass e, a, and 
tracing with this opening two small arcs, from the point e, 
and from the point 4, which intersecting at o, give the 
centre of the arc e, Jc, 4, traced by the radius e, a; this 
determines the curve required for this second fluke. 

We thus obtain the figure which should be given to the 
escapement-anchor exactly traced, and to procure isochronal 
vibrations it is only necessary to execute it by these 

§ X. — Anchor-escapement as improved by Graham for Regu- 
lators and Belfry-clocks, 

Figure 25, Plate IV., shows this escapement. It will 
only be necessary to say a few words of this after the 
details of construction of the anchor for mantel-clocks, 
given in the first part of the preceding paragraph. The 
escapement-wheel is at A, the escapement-anchor, B, has 
its centre of motion at a, at a distance of three times the 
radius of the wheel A. The dead-beat is made upon an 
arc of a circle, C, D, E, which passes through the centre of 
the wheel A. Each tooth of the wheel, therefore, reposes 
alternately upon the outer arc, D, E, on one side, and upon 
the inner arc, C, on the other ; these two arcs belonging to 


the same circumference of circle. A tooth passes at each 
oscillation of the pendulum. 

To find the inclination of the planes, we determine the 
number of degrees which the pendulum is required to 
describe, and form an angle, f a, g, on one side, and another, 
h, a, b, on the other, each of half the degrees which have 
been fixed on. In this construction, as we have indicated 
for the anchor of the mantel clocks, the sides of these angles 
will give the inclination of the planes, C, 1, for one of the 
flukes, D, 2, for the other. 

XL — Pin Escapement of Lepaute, for Regulators and 


Figure 26, PL IV., shows this escapement, whose first 
piece is an arbor, F, placed horizontally and terminated by 
two pivots, one of which rolls in the pillar-plate of the pil- 
lars, and the other in a cock fixed outside of the other 
plate. The fork of the pendulum is riveted upon the arbor, 
between the cock and the pillar-plate. 

This arbor bears two recurvated arms, G, A, c, and H, B, c?, 
which are fixed on it with a hard friction in such a manner 
that they can be opened more or less, and caused to make 
the angle necessary for the effects which may be desired. 

The parts, E, I, L, S, of the arms, are arcs of a circle whose 
centre is in the plane of the wheel and upon the axle, F, 
but they are terminated by the inclined planes I c and L d. 
The arm, G, A, c, passes behind the wheel, while the arm, 
H, B, c?, is upon the front part of the wheel. The wheel 
bears pins upon its two faces which are perpendicular to its 
plane. We have left those in white which are in front of 
the wheel; the black pins, placed alternately with the 
others, are on the back part of the same wheel. 

The wheel descending by the force of the weight from u 


98 the watchmaker's manual. 

to "sc, as indicated by the arrow, the pins of the front part 
encounter the inclined plane, L, d : and impel it towards B. 
By this movement, the arm, Gr, A c, which is on the other 
face of the wheel, is advanced beneath the following pin ; 
the pin, Y, having then escaped at the point d, and the arm 
continuing to turn by the force of impulse communicated to 
the pendulum, the following pin, w, is found upon the cir- 
cular concave part, E, I, which is the arc of repose. The 
arms being brought back from the side of A by the de- 
scending oscillation of the pendulum, the pin which rubbed 
upon the arc, E, I, directly encounters the plane, I, c, upon 
which it acts like the first, but in a contrary direction, 
pushing the arms of C A until the following tooth comes 
upon the arc L S, to descend thence upon the plane, L d } 
and so on. 

As each pin of the wheel answers to one oscillation of the 
pendulum, there should be sixty pins upon the wheel in the 
regulators, thirty of which are placed upon one of the faces 
of the wheel, and the other thirty in the intervals of the 
first, but upon the other side of the wheel. These pins, on 
both sides, are not placed precisely upon one circumference, 
or equidistant from the centre of the wheel ; but the pins 
which are to act upon the plane, I, c, act by their inner side, 
which is nearer the centre of the wheel, and the pins which 
push forward the plane L d, act by their outer side, which 
is further from the centre. These are arranged so that the 
inner sides of the pins, m, ?i, and the outer sides of the pins, 
x, y, are precisely upon the same circle ; for this the pins of 
one of the faces of the wheel must be placed on a circle 
whose radius is less by the diameter of the pin than the 
radius of the circle upon which the pins of the other face 
are planted. By this means, the impulse upon the two 
planes is made at exactly the same distance from the cen- 
tre of the wheel, and by an arm which is always equal. 


If the two pins were sound, the one which would come 
to the extremity, c or o?, of the plane, would escape as soon 
as its centre should be opposite the angle, e?, or o, and before 
the entire thickness of the pin would have passed between d y 
or c. Now, as the whole thickness of the arm, I, c, or c?, L, 
should pass between the two pins, and as it can only pass 
there when the entire pin shall be beneath c or d, it there- 
fore follows, that this pin will descend to the value of its 
radius after having escaped, and consequently the pin that 
is above will fall in the same proportion ; but this fall 
should always be avoided, both on account of the jerking 
and wear which it produces in the pieces, and the loss of 
force which is uselessly employed in the shock. 

By cutting off half the thickness of the pin, it will be 
able to pass beneath the arm as soon as it has escaped, and 
the following pin will come upon the arc of repose without 
any fall. 

Although the pins may be reduced to semi-cylinders, it 
is still their convexity or their lower surface which rubs 
upon the arcs of repose. Now there can be no slighter 
friction of surfaces than that of a convex upon a plane sur- 
face ; and the oil and dust which accumulate beneath the 
surface of a tooth, and which contribute to the wearing out 
of every other escapement, cannot collect under so thin a 
pin. These pins act upon the inclined planes by their con- 
vexity, sc, ra, 2/, 7i, and do not escape until the angle of the 
pin has reached the lower angle of the inclined plane. This 
escapement, therefore, unites all the advantages which have 
been sought in these pieces without any defects. 

The dead-beats are perfectly equal and at the same dis- 
tance from the centre ; the friction upon the arcs of repose 
is very slight ; the two arcs of repose are both concave, and 
are passed over with the same velocity, the same force, and 
in the same direction. The arms by which the wheel acts 


are alike, as well as the planes "upon which they act ; the 
impulse commences at the same distance from the centre, 
ends at the same distance upon both, and is made with an 
equal force and in the same manner. 

We will add an improvement to the construction which 
we have just given in the words of the author. It consists 
in placing a brass plate upon one of the arms, Gr, A, c, which 
can take a small circular movement. This plate is wormed 
in a direction perpendicular to the line F I. Upon another 
arm and opposite is placed another plate in which the head 
of a screw is inserted, which only permits it to take a cir- 
cular movement around its axle. The helices of this screw 
are wormed into the plate which is placed upon the other 
arm, so as to perform the functions of an adjusting screw. 
The result is, that by turning the head of this screw to the 
right or left with a key, the two inclined planes are drawn 
together or separated in order to adjust the escapement with 
precision. Artisans will readily understand this con- 



" The fact that heat expands all metals, and that cold 
contracts them, is universally acknowledged and proved by 
experience," and " as it happens," adds Berthoud, " that 
we do not experience the same degree of heat for two con- 
secutive moments, we may therefore say that all the particles 
of the body which we formerly considered to be in a state 
of rest are, on the contrary, in perpetual motion, and that 
this body is consequently larger in summer than in winter, 
and in the day than in night. 

11 We also know that the longer the pendulum is the 
slower will be its vibrations, and that the shorter it is the 
more will they be quickened. 

" Now, as the heat lengthens the rod, we see that in sum- 
mer the pendulum-clock will lose, and in the winter will 
gain time by this action. These causes would prevent the 
regular movement of the machine, and in order to attain 
perfection for it we must understand the amount of expan- 
sion and contraction of the different metals by cold and 
heat, and find a method of correcting these defects." 

The reasoning which Berthoud applies here to clocks is 
also applicable to all regulators ; as in watches the spiral- 
spring as well as the balance is subject to the same laws of 
expansion and contraction. The method used to correct 
these defects is known by the name of compensation. 


From the innumerable methods which have been invented 
for obtaining the compensation we shall choose those which 
seem to us to be the surest and best, referring curious 
readers to the works of Thiout Sen., Lepaute, Berthoud, and 
others, for descriptions of the remainder. We shall first 
point out the methods used to obtain the compensation in 
watches, after which we shall speak of the same methods 
as applied to the pendulum. 

The principal piece employed in all compensations is a 
bi-metallic rod, or one composed of two metals, whose ex- 
pansion and contraction by heat and cold are in different 
proportions. For this brass and steel are generally used, 
and numerous experiments have proved the expansion of 
the brass to that of the steel to be in proportion of 121 to 74. 

It therefore follows that if we suppose a bi-metallic rod, 
formed of a rod of brass, and a rod of steel of the same 
length, width, and thickness, to be fastened together by 
riveting, or, which is better, by soldering ; and if we also 
suppose these two rods thus united to be solidly fas- 
tened by one extremity upon the pillar-plate, while the 
other is left free, the heat acting upon them will lengthen 
the rod of brass beyond the rod of steel, and will force 
the latter to bend down on the side on which it is placed. 
The cold, on the contrary, will contract the brass more than 
the steel, whose extremity will describe an arc in a direc- 
tion contrary to the first. 

Skilful clockmakers have profited by this well-known 
property in metals, and have applied it in different methods, 
both in watches and in clocks, for obtaining the corrections 
or compensations which they sought. 

I. — Compensation in Watches with Circular Regulators. 
If the irregularity of watches proceeded only from the 


expansion or contraction of the material of which the 
balance and the spiral -spring are formed, there is no doubt 
that the use of a bi- metallic band, properly applied to the 
escapement, would correct the fault which we seek to 
remedy, but, unhappily, this is not the case. 

Better to explain what we have to say, we shall divide 
the numerous watches which are manufactured into three 
distinct classes. In the first of these we shall place those 
known as chronometers, of which we shall not specially 

In the second class are comprised those watches which, 
though less costly and less accurate than the first, have a 
much more regular movement than those of the third class, 
commonly called the balance-wheel watches. 

We will limit ourselves to the description given by M. Des- 
tigny, of Rouen, of the principal methods used to obtain the 
perfection of the watches of which we speak. These improve- 
ments consist in reducing the frictions, and rendering them 
as nearly equal as possible by causing the pivots to revolve 
in holes made in jewels, in furnishing the rubbing parts of 
the escapement with jewels, in making this escapement in 
such a manner that it may be able to correct the inconveni- 
ence of a variable motive power, and in making an appli- 
cation of a well-tempered spiral-spring, whose oscillations 
may be isochronal in all conditions. 

Isochronism, or the equal duration of the oscillations of 
the balance, is the basis of exact time-keeping, but there 
are so many causes which concur in affecting this isochro- 
nism, that those who seek to obtain it will attempt it in vain 
if they do not join a knowledge of mathematics and physics 
to that of the laws of motion. 

" Independently of the action of the temperature upon 
the spiral- spring, which by expanding or contracting ren- 
ders it weaker or stronger, and thus diminishes or increases 


its action on the balance by retarding or accelerating the 
vibrations, consequently causing the watch to gain or lose 
time ; it also influences the balance in the same manner, 
augmenting or diminishing its diameter, and thus producing 
a second cause of irregularity. 

" The cold acting upon the oil in the pivots and causing 
it to lose its fluidity, augments the resistance of motion in 
the proportion of the amount of the frictions, which occa- 
sions a delay in the movement. This effect can be infi- 
nitely varied, as it results from the difference of the fric- 
tions, which are increased or diminished in proportion to 
the size of the pivots, the diameter and weight of the ba- 
lance, and the extent of the space which it passes over. 
We see that the cold, in exercising its influence upon the 
different parts of the watch at the same time, produces two 
contrary effects, as it were, a natural compensation. If 
these opposing effects were in the same proportion, an ex- 
act compensation would be established which would render 
the employment of another compensation useless, or rather 
injurious. If, on the contrary, the delay arising from the 
increase of the frictions was greater than the advance caused 
by the contraction of the spiral-spring, the cold would re- 
tard the watch, and in this case the compensation would 
be still more objectionable as it would increase the varia- 
tion. The same reasoning may be applied inversely to the 

This theory explains why a change of temperature causes 
some watches to gain and others to lose, and it also explains 
why a common watch executed by an indifferent work- 
man may run regularly for a little while, while another 
watch which is really well executed, but which has no 
compensation, gains or loses with the heat or cold. 

The compensation represented in Figure 27, PI. IV., was 
invented by Breguet. This is a bi-metallic band, c, of steel 


and brass soldered together, the steel being outside. This 
band is turned back upon itself, following the circumfe- 
rence of the balance. It is fastened with a screw upon the 
rack, b, a part of which is seen here. The inner branch is 
free, and carries the arm at its extremity, which presents 
itself before a pin which is riveted upon the same rack. 
The spiral-spring, d, vibrates between this arm and the pin. 
We see that there is no facility given here for elongating 
or shortening the bi-metallic band, and that if it compen- 
sates it is chiefly the effect of chance. 

Compensation of M. Destigny. 

M. Destigny, after having studiously reflected upon the 
inconveniences arising from this construction, remedied them 
by placing a second rack upon the first, but in such a 
manner as to be drawn along by it. Upon this second 
rack he fixed an angular arm, hinged at the top of the an- 
gle, and with the aid of a small spring he forced the two 
sides of this angle to keep constantly apart. The movable 
side is incessantly impelled against the arm of the Breguet 
compensation, and bears another arm similar to the first at 
its extremity. This arm presents itself before the pin of 
the spiral-spring, which vibrates between the two. 

It is evident that as the compensation no longer acts 
directly upon the spiral-spring, but upon the additional 
arm, the desired compensation may be easily obtained by 
advancing or drawing back the arm. We shall not describe 
this mechanism at length, as simpler methods have since 
been invented. 

Compensation of M. Perron. 

In the year 1821, M. Perron, jr., a watchmaker of Be 



sancon, addressed an explanatory memoir of his invention 
to the Society of Encouragement, which may also be found 
in the Annales de V Industrie, vol. iv. 

M. Perron employs a bi-metallic band like that of Bre- 
guet, but not turned back upon itself, — it is extended and 
turned in a semicircle (Fig. 1, PL V.) This is fixed by 
the neck-screw, a, to the large end of the rack. This 
screw enters into a circular grooving which permits the 
elongation or shortening of the bi-metallic band, b. This 
band bears a curb, c?, at its free extremity, which moves 
along the band in order to regulate the compensation. 
This compensation is formed of a steel band of three- 
eightieths of a line in thickness, upon which a brass band 
of five-eightieths of a line is soldered, so that its total thick- 
ness is about eight- eightieths of a line. To obtain the ex- 
act compensation of the effects of the temperature, the com- 
pensator must be made longer than is necessary, so that 
the correction may be too great ; that is, that the watch 
may gain time by heat and lose it by cold. 

The watch is set in motion at 27 or 28 degrees of the 
thermometer of Reaumur ; in this state the spiral-spring 
should have very little play between the pin of the rack 
and the extremity of the angle of the curb's play. The 
temperature is then lessened and the watch is regulated by 
12 or 15 degrees; after which it is exposed to the heat of 
27 or 28 degrees, and finally to the cold of the freezing 
point. If the watch loses by cold and gains by heat, the 
curb should be removed from the extremity of the compen- 
sator, and the band bent down so that the curve may be 
opposite the pin of the rack, in order to obtain the exact 
correction of the effects of the temperature ; if this should 
be reversed, that is, if the watch should gain by cold and 
lose by heat, the effect of the compensation should be in- 
creased by lessening its thickness, — but this seldom hap- 


pens. The length of the compensator should be a little 
more than half that of the circumference of the balance. 

Compensation of M. Robert, jr. 

In 1829, M. Kobert, a watchmaker , of Blois, invented 
another compensation, also based on the bi-metallic band 
of Breguet, but far more easily executed than that of M. 

He rests a bi-metallic arc, 6, upon the rack, a (Fig. 2, 
PL V.), to which he gives a nearly circular form. One of 
the ends is fastened to the circumference of the circle at c, 
and the other is free, according to the usual method ; but 
the screw which maintains the piece permits it to turn with 
a slight friction upon its centre as upon a pivot, so that any 
point of the convexity of the bi-metallic arc can be opposed 
to the curb-pin. The further this point is from the extremity 
in which the screw is placed, the more marked is the effect 
of the expansion ; the larger the space which separates the 
compensative arc, and the greater the liberty given to the 
spiral-spring in its vibrations, the more effect will the com- 
pensative arc produce. It only remains, therefore, to sub- 
ject the piece to the trial of two extreme temperatures, and 
to turn the bi-metallic arc upon the screw, which serves as 
its pivot, until a constant movement has been obtained for 
the watch in these two conditions. A few easy trials will 
soon effect this. 

M. Duchemin, of Paris, has perfected this invention, which 
is remarkably ingenious and simple, by placing a curb, like 
that invented by M. Perron, towards the free end of the 
bi-metallic arc. The spiral-spring is thus held fast as 
between two pins, and, in unrolling itself, is not obliged 
to lie upon the bi-metallic arc. 


II. — Compensation in Pendulum Clocks. 

The effect of the temperature on metals — expanding them 
by heat and contracting them by cold — is always the same 
whatever form may be given them, for these effects take 
place in every direction. When the experiments of learned 
philosophers had confirmed this truth, and had proved that 
different metals expanded in different proportions, skilful 
clockmakers felt convinced that it was very important to find 
a sure method for remedying the effects of the temperature 
on the pendulum, in order to render its length invariable. 

When, by careful experiments, the proportion of expan- 
sion between brass and steel had been found to be in the 
ratio of 121 to 74, it was sought to combine rods of steel 
with rods of brass in an inverse proportion ; that is, to give 
to the bands or rods of steel a length as 121, and to those 
of brass a length as 74. They proposed to take these 
lengths from the centre of motion to the centre of oscillation. 
The centre of motion of the pendulum is always easily found, 
but the centre of oscillation presents many difficulties, as 
we shall see in a succeeding chapter. They did not con- 
sider that the proportions between the brass and the steel, 
which we have just given, are not constant — that these 
proportions change according to the nature of the brass or 
the steel, and the degree of hardness that it has acquired by 

The same causes which produce variations in the com- 
pensation of the regulators of watches, and which M. 
Destigny has so well explained, also affect the pendulum, 
or regulator of clocks. We could, therefore, only succeed 
in exactly compensating the effects of the temperature upon 
this pendulum by chance, as we have proved concerning 
the balance, or the regulator of watches. 


In mantel-clocks M. Destigny employs a bi-metallic band, 
composed of a band of brass and a band of steel, of equal 
dimensions, which are soldered together and fixed upon the 
pillar-plate by a foot which is placed upon the bottom of 
the bi-metallic band, the steel occupying the upper part. 
This arrangement may be seen in Figures 28 and 29, PL IY., 
in which D is the bi-metallic band, fixed to the pillar-plate 
by the screw C ; the other extremity of this band passes 
into a species of cap into which the suspension-spring also 
passes. The screw that is fixed to the centre of the head, 
Gr, serves to raise or lower the pendulum-ball, and hence to 
regulate the movement of the clock. We remark in this : 
1st, that the bi-metallic band is fixed, as the author states in 
his description ; 2d, that the bi-metallic band supports the 
weight of the pendulum and pendulum-ball, suspended at 
the end of a spring-band, which he has judiciously substi- 
tuted for the silk frequently used in these pendulums ; 3rd, 
that a cock, B, is fixed upon the pillar-plate by a screw and 
chicks, bearing two cheeks between which the suspension 
spring passes freely and without play. 

We are sorry that the author of this construction has not 
gained from it all the advantages of which we believe it to 
be susceptible. We have conceived the following slight 
improvements : — 1st, Suspend the pendulum by two very 
slight springs, supported by their two ends, between two 
brass bands, at the distance of two and a half or three lines 
apart. 2d, If the pillar-plate is square, place the bi-metallic 
band near the upper edge of the pillar-plate (Fig. 30), and 
give it a straight form ; if the pillar-plate is round, as it is 
generally made, and as Figure 28 represents, give to the 
band the circular form of the pillar-plate ; but do not fix it 
immovably by its foot, C, with the aid of a notch, in an arc 
of a circle which has its centre in the centre of the pillar- 
plate, but allow the opportunity of advancing or receding 


to this band, in order to establish the nearest compensation. 
This property of advancing, or of receding, can be obtained 
by an adjusting screw; this piece is fixed by the screw, L 
(Fig. 30). 3rd, Suppress the cock, B, and replace it by a 
piece, M, which bears two cheek-pieces, between which 
the two suspension-springs pass freely and without play. 
This piece, M, slides freely and without play on the pillar- 
plate, and can have no movement, except in a vertical direc- 
tion. Four strong pins, parallel to each other, are fixed in the 
upper part of this piece, which receive the free end of the 
bi-metallic band freely and without play. 4th, The little 
frame of the suspension -springs is carried by the end of the 
screw, N (Fig. 31), in such a manner that, by turning the 
head of this screw, the pendulum may be lengthened or 
shortened, and the clock regulated at will. 

By this construction — 1st, the bi-metallic band is inde- 
pendent of the pendulum, it no longer supports it ; and this 
weight, however slight it may be, can affect the regularity 
of the compensation ; 2d, by giving the facility of length- 
ening or shortening the bi-metallic band, we can obtain the 
greatest regularity in the compensation. 

We give a sufficient length to our bi-metallic band to 
enable it to compensate according to the length of the pen- 
dulum. Each metal is half a line in thickness, and the band 
is two lines in width ; consequently by separating the two 
suspension-springs to the distance of three lines, it passes 
easily between the two, and its sole function consists in ele- 
vating or lowering the point of suspension by moving the 
piece, M, which, if properly made, will offer no resistance. 

This construction is equally applicable to the regulators 
whose pendulums beat the seconds with a spring-suspension, 
and is free from the inconveniences of the former inven- 

But when the clock has a suspension of the pendulum, 


which is judiciously adopted in good astronomical clocks, 
the same method cannot be employed ; the ingenuity of the 
artists, however, has overcome this difficulty. 

A well adapted and ingenious construction was invented 
by M. Charles Zademach, a clockmaker of Leipsic. 

The same letters indicate the same objects in the three 
Figures, 3, 4, and 5, PL V. 

Two steel bands, A A (Fig. 4), are screwed upon two 
pieces of brass of the same thickness which we see at i 
(Fig. 4), and at y (Fig. 5), and hold them parallel to each 
other. These two figures are supposed here to make but 
one, and are joined by the ends at A, A, in order to form 
the entire length of the pendulum, which they show in 

At the lower extremity of the brass band, B, the double 
screw, w, u s is fixed (Fig. 3) ; this band is supported in its 
position between the two others by the segments of circle, 
\ h, (Fig. 4 and 5), which hinder it from approaching 
nearer to one than the other, and by two friction-rollers, 
c?, d, (Figs. 3, 4, 5), which traverse it, and which are them- 
selves traversed by an axle or screw, g, g ; the apertures 
made in this band for the passage of the rollers are, as we 
see in// (Fig. 3), large enough and long enough to prevent 
these rollers from becoming obstacles to the movements of 
extension and contraction which the changes of temperature 
occasion in the band. We see at x (Fig. 5), how its upper 
extremity is bound to the brass piece, y. 

The compensation is effected by the means of the two 
levers, C, C ; their axle or point of support, t, t, is fixed upon 
two steel bands, and while the excess of the extension or 
contraction of the brass band over the others is shown 
upon the two arms of its levers by the screw-nuts, D, D, the 
other raises or lowers the cross-bar, b, b, and with it the 
cylindrical cross-bar, a, to which the crossing, E, E, is sus- 


pended, which supports the pendulum ball, K ; so that the 
latter mounts or descends according to the degree of expan- 
sion or contraction taken by the steel bands. The letters, 
c, c, (Fig. 3 and 4), indicate the grooving in which the 
cylindrical cross-bar, a, moves. 

The design of the two screw-nuts, D, D, of the double 
screw, w, u, is to regulate the course of the extremity, v, v, 
of the levers, by placing them at a greater or less distance 
from their point of support, t. It is evident that the nearer 
the point on which the screw-nut rests is to the axle of the 
lever, the greater will be the course, v, when the band, B, is 

The pendulum-ball, K, of which we see but a part, is 
fixed upon the crossing, E, E, which terminates the pen- 
dulum we have just described. The separation of the two 
branches of this crossing is determined by the separation 
and thickness of the steel bands, A, A, and by the ease with 
which the crossing can glide along these two bands when, 
by the excess of expansion of the brass band over the 
latter, the cylindrical cross-bar, a, which supports the cross- 
ing, is raised. The two screws, t, Z, placed at the upper 
end of the branches, E, E, (Fig. 4), support them in their 
position without affecting the movement which the crossing 
should obey. 

Effects of this Pendulum. 

If we suppose this instrument set in a place whose tem- 
perature is suddenly raised, the three bands, A, A, and B — 
the two first of which are of steel and the last one of brass — 
will expand unequally and in the proportion that we have 
already indicated — that of 121 to 74. The band, B, which 
we may call the compensator, propped at the top by an 
invincible obstacle, y (Fig. 5), and at the bottom by the 


two levers, C, C (Fig. 3), will exercise its expansive force 
upon the points of contact of these two levers and the screw-- 
nuts, D, D, will sink in a quantity equal to the excess of the 
extension of the band, and will determine the elevation of 
the cross-bar, 5, b, which rests upon the extremities, v, v, of 
the levers. 

In order to obtain the exact compensation in this move- 
ment, the cross-bar, 6, Z>, and consequently the cylindrical 
cross-bar, a, to which the crossing of the pendulum- ball is 
suspended, must wind up in a proportion equal to that of 
the expansion of the steel bands of the pendulum ; this is 
easily done by combining the arms of the lever in such a 
manner that, v, /, or the larger arm, may be as small as the 
space passed over by the extremity, v, is to that passed over 
by the point of the lever, C, upon which rests the screw- 
nut, D ; that is, that v t shall be to t c, as 121 is to 74, or 
as 60*5 : 37, or in the proportion of the expansion of the 
two metals. This consideration is useless, as we shall see, 
and will be rejected on account of the difficulties which this 
theory represents. The two arms of the lever should be 
made alike, and, by some experiments with the pyrometer, 
the screw-nuts, D, D, will directly fix the exact point of 
difference of these two levers for the exact compensation. 
If one wishes to convince himself of this, after having made 
the arms of the levers equal in length, let him divide the 
arm, C, C, into sixty and a half equal parts, and he will be 
convinced, after having found the exact compensation, that 
the screw-nuts, D, D, will be fixed near the 37th division. 

If the metallic pieces always expanded in a quantity pro- 
portional to their dimensions, it would be possible to assign 
in advance the degree of extension which their surfaces 
would take, and to determine precisely, in a case like the 
latter for instance, the point of the levers to which the motive 
power of the compensation should be applied ; but as we 


have already said, two similar pieces of the same metal 
rarely expand equally ; it is therefore necessary to find for 
this new pendulum a method of correcting the difference 
between the true and the calculated expansion. 

We use the expressions of the true and the calculated ex- 
pansion to designate the actual expansion which a piece takes, 
and that which it should take in accordance with a general 
rule, determining the degree of expansion proper to each 
substance. For instance, a piece of brass of a certain size 
might expand itself three lines and a half, when, according 
to observations for determining its extension, its expansion 
ought not to exceed three lines ; its true expansion would 
therefore be three lines and a half, and its calculated expan- 
sion three lines. 

M. Zademach, who has also observed this, has chosen the 
most simple and natural method by adopting screw-nuts to 
transmit the expansive force of the band, B, to the levers ; 
for by the aid of these screw-nuts we can, as we have 
already remarked, easily find the point of the small arm of 
the lever to which the compensator should be applied in 
order to produce, at the opposite extremity, an effect 
equalling the degree of expansion of the steel bands. It is 
only necessary to bring the screw-nuts near the point, t, t, 
or the points, Z, Z, to correct the inequality produced in the 
movement of the pendulum by a false compensation. 

Other Methods of Compensation. 

In 1829, M. Henri Robert, a pupil of Breguet, and a 
practical clockmaker, presented to the Society of Encou- 
ragement two new methods for effecting the compensation 
of pendulum-clocks. 

1st Method. — M. Robert having remarked that platinum 
expands but slightly, while zinc has a great dilatation, in 


the proportion of 294 to 85, executed a half-second pendu- 
lum of these two metals in the following manner : — 

He formed his pendulum-rod of a platinum-tube of 13J 
inches in length, including the suspension, and of a pen- 
dulum-ball of 5 1 inches in diameter, terminating it towards 
the carrier screw-nut by an end-piece, of one inch, all of 
zinc, and cast together. 

The report which was made of this invention, by M. 
Hericart de Thury, may be found in the Bulletin de la 
Societe d 1 Encouragement, vol. xxviii., p. 50. " M. Robert," 
says the learned reporter, " has obtained the conditions 
which he sought, — 1st, by utilizing the dilatation of the 
pendulum-ball, usually counted as nothing, and conse- 
quently neglected; — 2d, by having a very short rod, in 
order that the centre of oscillation may coincide as nearly 
as possible with the centre of gravity of the pendulum- 
ball; — 3d, by making this rod of a slightly expansible 
metal, while the pendulum-ball possesses the contrary pro- 
perty in the highest degree; — 4th, that its compensation, 
although made of platinum, is but little more costly, and 
that its price, in clocks of precision, will not be sufficiently 
increased to hinder its use from becoming general." 

Id Method. — Fir- wood has long been known to possess 
the property of preserving an almost equal length in all 
changes of temperature. Several clockmakers, particularly 
M. Wagner, presented in the exposition of 1827, a large 
clock, whose pendulum, beating seconds, had a rod of fir. 
This wood is also known to have a propensity to twist, in 
accordance with the hygrometrical influences of the atmo- 
sphere. M. Robert succeeded in forming his new compen- 
sation in such a manner as to profit by the almost inexten- 
sible property of the fir- wood, by sheltering it from the 
influences of the atmosphere, and thus opposing its torsion. 

The rod of the pendulum is formed, — 1st, of a prismatic 


case of brass with a rectangular base ; — 2d, of a pendulum- 
ball of the same metal, pierced in its diameter with a 
mortise, into which the prismatic case glides easily but 
without play ; — 3d, of a rule of fir-wood terminated at 
each end by a little case which surrounds it ; the case fixed 
at the upper end bears a collar which rests on the extremity 
of the tube, and the suspension-hook is fixed above this 
collar. The lower case bears a wormed rod at its ex- 
tremity, which receives a screw-nut, and the counter-nut 
for supporting the pendulum-ball firmly. 

It is evident in this construction, that the wooden rule, 
which is inextensible, will keep the pendulum-ball at a 
fixed height ; it is therefore the expansion of the radius of 
this pendulum-ball which compensates the expansion of the 
suspension-hook of the prismatic case, and of the other 
parts. This may be made of any size, only observing that 
in its construction the wooden rule should be made as long- 
as the apparatus will permit, that the rule should enter the 
prismatic case freely, without touching the sides of it, and 
that it is only fixed there by the thickness of the band 
forming the outline of the small cases which terminate the 
ends of the rule. These two cases should fit exactly into 
the ends of the prismatic case. 

This pendulum is very simple, but the calculation is not 
sufficient to determine the lengths of the different metals 
employed in the compensation, which can be obtained only 
by experiments ; this the author has formally confessed. 

We fully approve of the fir rule of M. Kobert, inclosed 
in a prismatic case of brass, in which it is sheltered from 
the hygrometrical influences of the atmosphere, and, con- 
sequently, can experience no alteration ; for if the fir wood 
is inextensible by the temperature, it is affected by humi- 
dity. The Viscount du Molard has proved by exact expe- 
riments, that the silver fir is elongated to one eight hundred 


and ninetieth of its original length, taken at the zero of the 
hygrometer of Saussure. 

The lower mechanism which supports the pendulum-ball 
in the invention of M. Zademach can be successfully ap- 
plied to the construction of M. Kobert ; and an easy method 
is thus obtained for compensating the dilatation in pendu- 
lums with exactitude. 

Mercurial Compensation. 

In order to obviate the difficulties attendant upon the 
frequent trials necessary to obtain an exact compensation 
of the zinc and platina ; the method of adjusting a steel 
or glass tube filled with quicksilver to a steel-rod, and thus 
obtaining a speedier compensation, has been successfully 
adopted. For this purpose a tube eight inches long is 
attached to the rod — the exact quantity of quicksilver 
which it must contain can only be ascertained by actual 
experiments; this, however, is very easy, it being only 
necessary to pour the quicksilver from or into the tube. In 
this the expansion of the ball alone forms the compensation. 

Compensations of MM. Lewi and Arnold — Chronometer 


Before the application of the pendulum as the regulator 
of clocks, the balance had been used for this purpose, but 
this was immediately abandoned after the invention of the 
pendulum ; yet as all exterior motion is opposed to the 
isochronism of the pendulum, the balance was still the only 
regulator which could be successfully applied to portable 
clocks. The addition of the spiral-spring to this regulator 
has produced a revolution in the measure of time and has 
permitted it to approach the exactness of the pendulum. 
The first invention relative to the application of the spring 


to the balance with the view to obtaining by its elasticity 
the power which renders the action of this kind of regulator 
similar to that obtained by means of the gravity of the 
pendulum, is attributed by the English to Dr. Hook, yet he 
seems to have made but a limited application of it ; Huy- 
ghens, extending this idea, substituted for the simple spring 
the hair-spring, which is much more advantageous to the 
isochronism of the balance. 

The alterations to which the lengths of the pendulums 
as well as the movements of watches are exposed by the 
variations of temperature have already been mentioned, but 
the balance-machines are still more exposed to irregularity, 
not only because the balance dilates or contracts, according 
to the raising or lowering of the temperature, but because 
the spiral-spring itself experiences the same changes. In 
proportion as the balance contracts, and as its diameter 
becomes smaller, it is no longer transported in its vibrations 
in the same manner but oscillates with greater rapidity; 
besides in proportion as the spring attached to the balanoe 
is contracted at the same time by the cold, it acts with a 
greater power, and these two effects unite in quickening the 
vibrations. Mr. Harrison has invented a method for cor- 
recting these inequalities, which consists in shortening or 
elongating the spiral-spring when the heat or cold may give 
it greater or less force. M. Leroi has invented another 
method, which has been modified by Arnold. It consists 
in producing a dilatation in the balance itself, instead of a 
contraction which would be the effect of the cold ; by this 
means the spring, in its greatest state of rigidity, acquires a 
compensative effect in its functions. This invention of 
Pierre Leroi is represented in Fig. 32, PI. IY., in which a 
chronometer balance is designed. A circular piece of steel 
is turned and hollowed out in a cup in such a manner as to 
form a circular grooving of sufficient depth ; into this 


grooving some brass of the best quality is placed together 
with a little borax in order to prevent the oxydation of the 
metal ; the whole is put in a crucible which is heated suffi- 
ciently to effect the fusion of the brass ; this last metal being 
in fusion, will adhere strongly to the brass without the 
necessity of using solder. The piece thus prepared and 
cooled is replaced on the lathe, and all the superfluous brass 
and steel are removed in such a manner as to obtain a regular 
circle whose exterior is of brass and interior of steel ; the 
thickness of the brass should be nearly double that of the 
steel. This done, the interior of the plate is hollowed out 
by means of the file and drill, leaving two or three equal and 
symmetrically placed radii ; in this state the exterior circle 
is cut in two or three places, even cutting off a portion as 
in Figure 32, and a small movable weight is adjusted to the 
extremity of each sector ; these masses should be equal in 
weight and susceptible of being moved and checked on the 
sectors at the distance from the radii which the essays made 
in different temperatures may prove to be best suited to the 

It is easy to demonstrate the manner in which this 
balance works in the changes of temperature. For instance, 
when the heat which generally tends to retard a watch by 
its action on the movement, the spiral -spring, and the radii 
of the balance, acts on this last, the sectors will contract and 
will consequently draw the masses near the centre to 
advance the watch ; this will effect the compensation, if we 
are certain of finding the distance at which this compensa- 
tion takes place, by the displacement of the masses. 

We have said before that the sectors are composed of 
brass and steel ; both are dilated, it is true, by the effect of 
the heat, but in an unequal manner, the brass more than 
the steel. The inner steel of these sectors being firmly 
bound to the outer brass, will counteract its greater -dilatation, 


and the effect of the curvature which will result from it will 
be to draw the masses nearer the centre of oscillation. This 
will be reversed by the effect of cold. 

Fig. 33, PL IV., shows a modification of the same prin- 
ciple adopted by Arnold. The compensative weights are 
cylindrical and are adjusted by screws to the ends of the 
sectors. These sectors are established on the extremity of 
the two radii which carry an interior circle ; this circle is 
furnished with three masses with friction which serve to 
poise the balance. 

The necessity of these different masses will be under- 
stood, when it is considered that the pivots of the balance 
sustain an unequal friction in the different positions of the 
chronometer, and that it is necessary that, the compensation 
being obtained, the balance may be still in equilibrium in 
every position. 

All these arrangements require experiments, which skill 
alone can abridge. The frictions should be the same, 
whether the balance rests on one of its pivots or on the 
cylindrical faces of both. The balance itself preserves a 
nearly permanent form, while the spiral-spring, in the 
vibrations, is more or less relaxed, and its distances from 
the centre are variable. It cannot be expected that a 
balance deprived of its spiral-spring, which is in this case 
in perfect equilibrium, shall still be so and furnish at the 
same time equal vibrations when it is in its place and in 
every position. Besides these difficulties, there is an epoch 
of vibration in which the force of the spring and the inertia 
of the balance are not simply in opposition in respect to 
each other, but are combined with the motive-power during 
the action of the escapement. The remedy of all these 
difficulties, which has been successfully applied in the con- 
struction of marine chronometers, is to maintain them- in 
such a position that the axle of this piece shall be con- 


stantly vertical ;* by this method this piece is not affected 
by the differences of gravity. As to the pocket chrono- 
meters, the. skill of the artists has conceived numerous 
ingenious methods which we cannot describe in our narrow 
limits. The general principle most in use, is to consider 
the balance independent in its adjustment like a pendulum 
which would be placed above and beneath its centre of 
suspension, acting by the gravity in the same time in which 
it is incited to repose by the elasticity. In such circum- 
stances, the vibrations will be more rapid when the fixed 
point of the equilibrium is below ; they will be slower in a 
contrary position of the machine. This indicates for a 
remedy the diminution either of the extent of the radius or 
of the burden of this side, which is the lowest when the 
velocity is too great. Thus, for instance, if one of the 
screws placed at the extremity of the radii of the first of 
the balances described above, finds itself below when the 
velocity is too great, it must be slightly turned so as to 
draw its weight nearer the axle, in the same time that the 
opposite screw will be loosened, and its weight carried a 
little outside. The defects of equilibrium can thus be 
remedied without any other derangement. If an imperfec- 
tion is perceived in the vibrations of the balance when it is 
tested in a vertical position, having its lowest point at rest, 
in a line making a right angle with that which passes 
through the middle of the radii, a similar change should be 
effected in the masses of expansion, either by a slight 
deflection of the circular sectors, or by altering the mass ; 

* The chronometer will consequently be in a horizontal plane. To keep 
it in this position despite the movements of the vessel, it is suspended on 
gimbals. This consists in supporting the case on two pivots placed above 
its centre of gravity, which pivots are themselves suspended on a brass ring, 
which is free to oscillate on the horizontal plane. The pivots of the case and 
those of the ring are thus perpendicular in their direction. 


122 the watchmaker's manual. 

or, which, is still better, by means of small screws fixed into 
the regulating masses themselves, which are thrown back 
from or drawn towards the centre of the balance in the 
same manner as are those placed at the extremity of the 
radii. By these methods, and by corresponding ones, the 
balance can be arranged in such a manner as to furnish 
equal vibrations in every position in which its plane is not 
parallel to the horizon; but these essays require much 
pains and care before exact results can be obtained. 

It often happens that chronometers tested in extreme 
temperatures, and regulated in these limits, are irregular 
in intermediate temperatures ; their balances then disagree- 
ing with the movements, these are replaced by others ; and 
the balances which disagree with such movements are often 
found to go well with the others. 

Sometimes it also happens that the balances compensate 
too much, but this is easily provided for by advancing the 
compensating masses of the sectors of the radii, and by 
taking care that this advancement does not change the 
equilibrium of this piece. As there are two kinds of 
movable masses, it is easy to obtain these conditions, which 
are essential to the regularity of the functions of the balance. 

A very curious observation was made in New Holland, 
by General Brisbane, the governor of this establishment ; 
he perceived that perfectly regulated chronometers, when 
they were set towards the east in a certain position in re- 
spect to the horizon, experienced some variations when 
changed from this position : the following explanation of 
this phenomenon has been given. 

Before attaining their definitive form, the balances of the 
marine chronometers-, composed, as we have already said, 
of steel and of brass, sustain a repeated friction from the 
burin and the file. This operation procures a factitious 
magnetizing to the balance, as may easily be perceived by 


submitting it to a contact with iron filings. These particles 
attach themselves to the radii and to the limb, and it there- 
fore seems that the balance is magnetized, and it is probable 
that it is polarized. 

If, in this state, a balance was disengaged from its spiral- 
spring, admitting it to be sufficiently free on its pivots and 
in a horizontal position, it would discover the east on 
account of the magnetic line of the place, in a manner 
closely resembling the needles of the compass ; but there 
would be, in consequence, other positions or poles of the 
same sort, also set towards the east, which would be re- 
pelled, while, in the contrary case, they would be attracted. 
Thus the position of the chronometer may be such with 
regard to the magnetic meridian of the globe,* that the 
balance experiences difficulties or facility in being brought 
back to its position, and these causes may be combined 
together, be avoided, be added or even poised.* 

On land it is easy to give to these instruments a fixed 
position in one locality ; but in a vessel, which so often 
changes its position with regard to the horizon, it is quite a 
different thing. Each ship, in respect to the quantity of 
iron, of cannon and steam engines which it contains, is a 

* Ships themselves contain so great a quantity of bars of hammered iron, 
cannons, and iron projectiles, that they may be considered as a magnetic 
mass possessing two poles and a particular magnetic meridian. Here, then, 
are three circumstances which may be combined to act by their sum or differ- 
ence on the movement of the balance of marine chronometers. 

Steam-ships are those most exposed to these variations by reason of the 
masses of iron which they contain and which is continually in motion. But 
not by transporting a chronometer to any part of the globe, and observing the 
differences when it is brought back to the point of departure, can we perceive 
them all. Steam-ships, not being subjected to the variations of route which 
may result from contrary winds, follow a direct line in their course, both in 
going and returning ; it is therefore probable that the errors will be compen- 
sated in a great measure by the two inverse positions of the ship, relatively 
to the magnetic meridian of the globe. 

124 the watchmaker's manual. 

polarized body ; its magnetic meridian combines with, that 
of the globe in a manner which differs in each ship, accord- 
ing to the locality, and it will not be strange if variations 
are found in each of them. These anomalous causes may 
have but a slight influence on chronometers, but as they 
may be added to others, it would be well to seek methods 
by which to provide for them. Other metals than steel 
may be employed in the construction of the balances of 
marine chronometers, platinum for instance, whose dilata- 
tion in proportion to the brass is still less than that of the 

The thickening of the oils which are used to lubricate 
the pivots of the trains, is not one of the least causes of 
variation, especially when great changes of temperature are 
experienced. These changes affect the liberty of the move- 
ment in proportion to the frequency of the renewal of the 
oils, and to the accumulation of particles in the pivot-holes ; 
this is also true of the dust, which it is very difficult to 
hinder from penetrating into the interior of the frames, 
however hermetically they may be closed. 



The circular balance is generally used as a regulator in 
portable clocks, or in those whose place is often changed. 
Steel was first employed in the construction of this, but 
was afterwards rejected, as it was thought that its attracti- 
bility to the magnet might affect the regularity of the clock. 
Brass, and sometimes gold, have been used for substitutes ; 
brass is generally employed. 

In all of the stationary clocks, the pendulum serves as a 
regulator. Here, the kind of metal employed is of less con- 
sequence, and the regularity of the movement depends, in 
a great measure, on the exact length given to the regu- 

In both cases, clock-makers must follow the invariable 
rules indicated by physics, and developed by the learned 
artists who have written upon this subject. We shall divide 
this chapter into two sections, in which we shall point out 
that which it is indispensable to know. 


Berthoud was the first who carefully studied and clearly 
described the solution of the different problems necessary 
to attain perfection in this important part of horology. 

The first watches that were constructed had small steel 

126 the watchmaker's manual. 

balances, very slight, and without a hair-spring; their 
movement was, consequently, very irregular. In 1695 the 
celebrated Huyghens invented the spiral or hair-spring, 
which he applied to the balance, thus causing it to produce 
vibrations independent of the escapement; the diameter 
of the balance was then increased, and its vibrations were 
perceived to be quicker and of less extent in proportion 
as the spiral-spring was stronger, and on the contrary, 
to be slower and more extended as the spring was 
weaker. It was therefore evident that a great degree of 
accuracy might easily be obtained by the combination of 
these three elements — the diameter and weight of the 
balance, and the strength of the spiral-spring, in order to 
obtain the greatest regularity. 

The principle was acknowledged, but its application was 
not easy ; science had not then progressed far enough to 
give the solution of so important a problem ; and they ex- 
perimented for a long time before they gained their object. 
Sully and Julien Leroi, the most skilful clockmakers of the 
beginning and end of the eighteenth century, had already 
opened the way, but to the indefatigable and learned Ber- 
thoud was reserved the task of bearing the light of science 
to an essential part of the art. It is not sufficient in the 
industrial arts to possess theoretical science in a high de- 
gree, but practice must also be joined to it; that is, one 
must be an artist to make a correct application of science. 
We have irrefragable proofs of this truth every day. Ber* 
thoud joined practice to theory ; it is not strange therefore 
that he threw a brilliant light upon questions which, until 
then, had been unresolved. 

In comparing the effects of the pendulum, of which we 
shall presently speak, with the balance moved by the 
spiral-spring, he reasoned in this simple manner : — "If a 
balance is made, to which a given impulse procures iso- 


chronal oscillations, and preserves its movement during a 
very long time, the frictions and the resistance of the air 
are reputed to be reduced to the smallest possible quantity, 
so that this balance will be the best regulator applicable to 
a watch. "We will therefore consider how we may obtain 

" It has been demonstrated that the forces which bodies 
in motion employ to overcome obstructions are in the com- 
posite ratio of their masses, and of the square of their velo- 

" Now, as the force produced in a body is equal to the 
action which causes it, it follows that the force which has 
been used to give a motion to a body, is as the product of 
the mass of this body, by the square of the velocity that it 
has acquired. If we compare two bodies of different dimen- 
sions, designating the parts of the large body by capital 
letters, and the corresponding parts of the small body by 
italics ; we will indicate the first body or the first balance 
by A ; its mass by M ; its velocity by V ; and its force by 
F ; and in the same manner we will designate by a, the 
second body or the second balance ; by m, its mass ; by v, 
its velocity ; and by/ its force; — we shall have this pro- 
portion:—/: F : : v 2 m : V 2 M. But as the product of the 
extremes is equal to the product of the means in every 
geometrical proportion, we shall have the following equa- 
tion:—/ V 2 M=F v 2 m, which is applicable to all cases. 

" 1st. If the two forces are equal ; that is, if we suppose 
that/=F, we can suppress them in both members of the 
preceding equation, as the two members are thus divided 
by the same number which does not change the quotients. 
Thus we shall have V 2 M.=v 2 m, which signifies that when 
the forces of two balances are equal, the masses, multiplied 
by the squares of their velocities, are also equal. We can 
draw a geometrical proportion from this last equation by 

128 the watchmaker's manual. 

considering the first member as the product of the extremes, 
and the second member as the product of the means ; we 
shall then have V 2 : v 2 : : m : M ; that is, when the forces 
of the two balances in motion are equal, the masses are in 
the inverse ratio of the square of the velocities ; or if the 
masses are in the inverse ratio of the square of the velo- 
cities, the forces of the balances are equal. For instance, 
if the velocity of A=l, and that of a=2, the square of the 
velocity of A=l, and the square of the velocity of a=4.; 
if the mass of the balance A =4, and that of a=l, by plac- 
ing these numbers in the place of the letters of the last 
equation Y 2 M.—v 2 m, which expresses the value of the 
forces of each of the two balances, we shall have 1+4= 
4+1 ; consequently both forces are equal since 4=4. This 
clearly proves what we have advanced. 

" 2d. If the masses of the two balances are equal, that is, if 
they have the same weight so that ra=M, the fundamental 
equation/ Y 2 M=F v 2 m, becomes/ Y 2 =F v 2 , by dividing 
the two members by the equal quantities m=M, from which 
we draw this proportion/: F : : v 2 : Y 2 ; which signifies that 
if two balances have equal masses and are moved with un- 
equal velocities, their forces are in proportion to the squares 
of their velocities. We will again substitute the numbers 
for the letters in the preceding proportion, to render it more 
intelligible to those unaccustomed to this form of calcula- 
tion. Let us suppose that the velocity of the balance A, 
expressed by Y=l, its square, or Y 2 =l ; that the velocity 
of the balance a, expressed by v=4, its square, or v 2 =16; 
and the preceding proportion will be thus transformed, — /: 
F : : 16 : 1, which signifies that the force requisite to sus- 
tain the movement of the balance a, is to that requisite to 
sustain the movement of the balance A, as 16 to 1 ; that is, 
these forces are as the squares of their velocities. 

" 3d. If the velocities of these two balances are equal ; that 


is, if v=V, the primitive proportion will become /: F : : 
m : M, and consequently the forces will be in the proportion 
of the masses ; the actions required to sustain the move- 
ment will, therefore, be as the masses, or as the weight of 
the balances. 

" 4th. In general, if the velocities and the masses of the two 
balances are unequal, their forces will be to each other as 
the composite relation of the product of the masses by the 
squares of the velocities; this is expressed by the primitive 
and fundamental problem/: F : : v 2 -f m : V 2 + M." 

From these principles, Berthoud resolved all problems 
relative to the balances, and determined their weights, their 
diameters according to the number of vibrations, the force 
requisite to make them pass over certain arcs, etc. 

" By knowing the mass of a balance, its velocity and the 
force which sets it in motion, in a well-executed and tried 
watch, we can easily deduct all the conditions required for 
the balance of another watch, when it should have a differ- 
ent mass, more or less velocity, more or less motive force, etc. 

" To compare the velocities of the two balances, we must 
multiply the number of vibrations during a given time by 
the diameter of each balance ; the products will express the 
velocities when they describe similar arcs, but when this is 
not the case, it is necessary to make a product of the three 
following quantities for each balance ; 1st, of the number of 
vibrations in the same time ; 2d, of the diameter or radius 
of the balance ; 3d, of the arc passed over by the balance. 
Some examples will show the application of this." 

Berthoud observes that these calculations relate to the 
cylinder escapement, but we add that they are applicable to 
all dead-beat or detached escapements, and generally, to all 
escapements which require the spiral spring. As to the 
balance-wheel watches, these calculations are useless; for 
all workmen know that it is easy to proportion the weight 



of the balance to the motive-power, whatever may be its 
diameter, the arcs it passes over, etc. It is only necessary 
to cause the watch to go without the spiral spring in such 
a manner that the minute-hand will pass over from 25 to 
27 minutes an hour, thus losing from 33 to 35 minutes an 
hour. Yet Berthoud observes that the amount of this loss 
should vary ; 1st, according to the frictions of the pivots ; 
2d, according to the size of the balances ; this loss, there- 
fore, cannot be precisely stated, as it varies in every watch, 
so that in those pieces in which great accuracy is wished, it 
will be well to determine by the same calculation the 
weight of the balance from the force of the motive-power. 

" To succeed exactly," says Berthoud, " in proportioning 
the weight of the balances of watches which go with the 
spiral-spring, to the motive-power, I commenced by con- 
structing an instrument by means of which I could with the 
greatest precision determine the force which the mainspring 
communicates to the train. By placing this instrument 
upon the square of the fusee in the same manner as a lever 
for equalizing fusees, the force of the spring may be esti- 
mated by the degree of the branch where the weight is 
stopped in order to equilibrate with the spring ; by com- 
paring the force of the motive-power with that of a watch, we 
determine the weight of balances," etc. A description of 
this instrument will be given in the chapter on tools. 

" To find the dimensions of a watch which we wish to 
make, we use, as a term of comparison, a good watch, 
arranged as well as possible, and constructed in such a 
manner as to reduce the frictions to the smallest quantity ; 
so that the motive power may have the requisite relation 
to the regulator, that the watch may go with the greatest 
possible accuracy. This done, we measure the diameter of 
the balance, and its weight ; count the number of vibra- 
tions which it makes per hour, and the extent of its vibra- 


tions; compute the force of the main-spring by means 
of the instrument of which we have just spoken; and 
finally reckon the time which the fusee, or the barrel-arbor 
when there is no fusee, takes to make a revolution. 

" I prefer the use of a carefully executed watch to deter- 
mine the dimensions of another, differently constructed, for 
two reasons ; 1st, because the calculation is more easy for 
the workmen, and 2d, because the dimensions are more 
exact than could be procured by calculation alone ; as the 
effects of the frictions are not sufficiently understood, the 
motive-power of a watch being given as well as the 
diameter of the balance, to be able exactly to ascertain its 
weight and the arcs which it should pass over; while by 
comparing it with a watch already made, these requisites 
are found at once, and the necessary dimensions can be 
obtained with more precision. 

Problem First 

" The dimensions of a comparison- watch, A, being given, 
to find the weight or mass of the balance of another watch, a, 
the diameter of its balance and the number of its vibrations 
being known." 

As calculation by decimals is more easily executed than 
by fractions, we have changed the solutions of Berthoud to 
decimal fractions. 

" In the solution of this problem, we suppose that in the 
watch a, the extent of the arcs of the motive power is of 
the same size as those of the comparison- watch A, and we 
demand that there shall be the same relation of the motive- 
power of the watch a, with its regulator, as there is between 
the motive-power of the watch A and its regulator. 

We give the following dimensions of the comparison- 
watch A, which is a cylinder-escapement like that which is 



to be made. We have placed below, in the same line, all 
the data of the watch a, placing the letters corresponding 
to the general formula before each article in order to facili- 
tate the operation. 



Comparison- Watch, A. 

Weight or mass of the balance, 
{ Diameter of the balance, 
( Vibrations per second, 

Extent of the arcs of vibration, . 

Eusee in 5 hours, 

Mainspring producing an equilibrium at 4£ inches 
from the centre of the fusee at, . 

grains, 6*25 
lines, 8-50 
degrees, 2 40 
revolution, 1" 

drams, 5-?5 

Watch to be Executed, a. 

m. Weight or mass of the balance, .... grains, x. 

( Diameter of the balance, lines. 10 25 

' I Vibrations per second, ...... 2* 

Extent of the arcs of vibration, ..... degrees, 2 40 

Fusee in 5 hours, revolution, I' 

/. Mainspring causing an equilibrium at 4£ inches 

from the centre of the fusee at, . . . drams, 5*15 

As the forces of the spring are supposed to be equal, we 
have the second proportion to resolve — V 2 : v 2 : : m : M, 
but 771 being the unknown quantity which we seek, this 
proportion becomes V 2 : v 2 : : x : M, which gives us the 

V 2 xM 

equation x= — . 


To obtain the velocity of the balance A, in figures, 8*50, 
which expresses the diameter of the balance, must be mul- 
tiplied by the 5 vibrations which it makes per second ; — 
this gives 42*50. By multiplying this number by itself, in 
order to raise it to a square, we have 1806*25, for the value 
ofY 2 . 


In the same manner, to obtain the value of v 2 , 10*25 must 
be multiplied by 2 vibrations per second, which gives 20*50, 
the square of which is 420*50 =v 2 . By substituting the num- 
bers which we have just found for the letters in the preceding 

, 1806*25x6*25 .. ,.' , . 

equation we have x= ; an equation which is 

^ 420*50 ' H 

resolved by the simple rules of arithmetic. The quotient 
will give the weight of the balance in grains. 

Problem Second. 

If the forces of the springs are not equal, this datum must 
be entered into the calculation, and the fundamental equa- 
tion or proportion which we have furnished executed thus, 
/ : F : : v 2 m : V 2 M ; in which we see that the forces which 
we had neglected, supposing them equal, become elements 
of the calculation, which is conducted in the same manner 
as in the preceding problem. 

Problem Third. 

In the two preceding problems, we have supposed that 
the two fusees, or barrel-arbors when there is no fusee, 
each make one revolution in 5 hours ; but if the watch 
to be constructed should make more or less revolutions 
than the comparison-watch, it becomes necessary, in order 
to be able to compare the motive powers, to reduce them 
to unity ; that is, to the force which will be necessary to 
move the slowest fusee. Thus, supposing the watch, a, to 
be an eight-day watch, whose fusee revolves in 40 hours, 
while the watch, A, performs this in 5 hours, we make 
this proportion: — If 5 hours require 5*75 drams of force, 
how much force does 40 hours require, and, consequently, 
5 : 5*75 : : 40 : x . In executing it, we find that the spring 

134 the watchmaker's manual. 

of the watch, a, should have a force of 46 drams, placed 
4 J inches from the centre of the fusee, and this new element 
will be added to the proportion, which will no longer pre- 
sent any difficulty. 

General Observation. 

Those of our readers who are accustomed to calcu- 
lations will perceive that the general proportion, or each 
of the proportions which the author has deducted from 
it, may be easily used to find one of the unknown ele- 
ments, the others being given. Let us suppose the same 
data which we gave in ascertaining the value of m, and 
that we wish to find the diameter to be given the balance 
of the watch, a. 

We will avail ourselves of the second proportion Y 2 : 
v 2, : : m : M. Our unknown quantity is found in the term 
v 2 , as it is the diameter of the balance, connected by means 
of multiplication with the number expressing the vibra- 
tions which it makes per second, and the product then 
raised to a square ; it is therefore necessary to invert our 
process for finding the value of v 2 . We then have the 

+ . . 2 1806-25x6-25 
equation v l or ar = . 

H 18-20 

In executing it we find cc 2 = 620*28, but this number is the 
square of x ; it is therefore necessary to extract the square 
root, which gives 24*90. This last number is the product of 
a multiplication, one factor of which is the required diameter 
of the balance, while the other factor is 2 per second. By 
dividing 24*90 by 2, we have 12*45 lines for the diameter 
of the balance, which differs a little from the 10*33 which 
Berthoud supposed. 

This author afterwards perceived this difference, and 
executed another comparison-watch, A, with still greater 


care, whose elements it is only necessary to give, as they 
do not change the principles, nor the forms of calculation 
which have already been shown. 

Comparison- Watch, A. 

M. Mass or weight of the balance, . 
„ ( Diameter of the balance, . 
( Vibrations per second, 
Extent of the arcs of vibration, . 
Eusee in 4£ hours, 
E. Mainspring causing an equilibrium at 4J inches 

from the centre of the fusee at, drams, 3. 

grains, 19-75 
lines, 10-50 
degrees, 2*4= ) 
revolution, 1" 

By substituting these data for those in the preceding cal- 
culations, much more accurate results may be obtained. 

Clockmakers have generally adopted for the dimension 
of the balance the same dimension of the diameter of the 
barrel. This seems to have been the practice of Breguet, 
and is nearly the same with that adopted by Berthoud from 
the calculation. 


The pendulum is the most important piece of the clock- 
work, as we have already said ; it is the true instrument of 
the measure of time, dividing the time by its oscillations, 
and regulating the velocity of the wheels by the escape- 
ment to which it is joined. By a double effect of the 
escapement, these same wheels transmit to the pendulum 
the force of the motive-power, and sustain its oscillatory 
movement, which the frictions and the resistance of the air 
tend to destroy. 

It is essential to neglect nothing connected with the study 
of the pendulum. Before arriving at the practice, one 

136 the watchmaker's manual. 

should therefore impress himself with the following prin- 
ciples which are adopted in physics. 

Theory of the Pendulum. 

The pendulum is used in the study of the gravity when 
its force is to be exactly determined. We know that, 
at Paris, the velocity which is communicated to a falling 
body is 32 feet at the end of a second, while in the first 
second the body only passes over 16 feet in its fall. To 
measure this force of gravity in a specific manner — the 
body falling too quickly — we must have recourse to the 
pendulum. The pendulum is of great importance in this 
respect, as it serves to mark the ratio of the force of gravity 
in different places, as we shall presently see. 

Another application of the pendulum consists in the 
balances of clocks. In this connexion it is very essential 
to study it in this work. 

We distinguish two kinds of pendulums, — the simple 
pendulum and the composite pendulum. 

The simple, or rather the ideal pendulum, consists of a 
heavy point, suspended by an inextensible thread without 
weight, and moving without friction around a fixed point. 
This pendulum cannot be realized, but we can calculate 
what its laws of motion would be if it existed. 

The composite pendulum is a body susceptible of being 
moved around a horizontal axis. The forms and dimen- 
sions of this are variable. Before investigating the laws of 
the pendular movement, we will examine the nature of the 
movement of a simple pendulum. 

Let us suppose a pendulum, A, B. We know that it 
will be in equilibrium when the thread by which the mate- 
rial point is suspended shall be vertical ; the action of the 
weight upon the movable part will then be destroyed by 


the resistance of the fixed point to which it is suspended, 
but if we draw aside the pendulum to an inclined posi- 
tion, and then abandon it, it will not remain there, but 
will descend to regain its original position, with swing- 
ing movements termed oscillations ; these oscillations in 
a simple pendulum would have equal duration and ampli- 

The weight that acts on the material point is a vertical 
force, which may be separated into two parts, — one, acting 
with the prolongation of the thread, is destroyed by the 
resistance of the fixed point, the other, acting in a perpen- 
dicular direction, has all its force, and attracts the movable 
part. This decomposition of the weight may be made at 
each point of the arc described by the movable part, and 
the nearer this movable line approaches the vertical, the 
more will the effective component diminish. It is evident 
that the weight will move as far as its original position 
with an accelerated movement, neither uniform nor uni- 
formly varied, for the effective component which causes it 
to act, although continually diminishing, yet transmits to 
it an accelerating force which adds at each instant to the 
first impulses, and thus augments its velocity. 

On regaining its primitive position, the pendulum will 
ascend on the other side by reason of its acquired velo- 
city, although the gravity which attracted the movable line 
is entirely destroyed. The gravity will then act again upon 
it, but as a force abating its velocity. It will ascend on 
the other side to the same height that it quitted, then re- 
descend, executing another oscillation precisely like the 
first. It therefore follows, that during the ascending move- 
ment of the pendulum, the weight will take away all the 
increase of the velocity transmitted to it in its descent. 

If we suppose the pendulum to be exempt from all fric- 
tion, the oscillations will constantly have the same ampli- 

133 the watchmaker's manual. 

tude and the same duration, and will be indefinitely con- 
tinued. But in performing the experiment with a compo- 
site pendulum, we are certain that it will stop ; partly on 
account of the resistance of the air, and partly because of 
the friction of the upper part of the pendulum. The fol- 
lowing are the laws of the pendular movement of which 
we have just spoken, that is of the simple pendulum : — 

First Law. — The oscillations are isochronal. By this we 
understand that they are executed in the same time, and 
that their duration is independent of their amplitude, so long 
as this amplitude does not exceed certain limits. 

Second Law. — The duration of the oscillations in the 
same place for pendulums of different lengths, varies in pro- 
portion to the square roots of the length of these pendulums. 
Thus, a pendulum which is four times the length of another, 
requires twice as much time for making an oscillation, or 
makes but one while the other makes two ; a pendulum 
nine times the length of another requires three times as 
much time for its oscillation, or makes but one while the 
other makes three. 

Third Laiv. — The duration of the oscillation is in the in- 
verse ratio of the square root of the weight ; that is, if the 
weight has 4, 9, 16 . . . times more intensity, the pendulum 
will beat 2, 3, 4 . . . times faster. 

These three laws are implicitly included in the formula 

t=v\ / — in which t is the time of an oscillation ; * the 
V g 

relation 3*14159 of the circumference to the diameter ; 7, 
the length of the pendulum ; and #, the intensity of the 
weight ; t is expressed in seconds, and I in inches. 

Composite Pendulum. — What we have said applies to a 
simple pendulum, oscillating in a vacuum, which cannot be 
realized, but if we suppose this pendulum to oscillate in the 
air, the resistance of the air will gradually diminish the 


amplitude, and finally stop the pendulum. The composite 
pendulums used in the arts and sciences are generally formed 
of a prismatic, or cylindrical rod, to which a heavy metal 
ball is suspended, and which rests by a steel suspension 
upon two polished planes of steel or agate. 

When a composite pendulum is set in motion, the con- 
nexion existing between all the parts of the apparatus 
necessarily requires that all the molecules — whatever may 
be their distance from the axis of suspension — shall exe- 
cute their oscillations in the same time. Now if the mole- 
cule A, which is the nearest the axis of suspension, were 
free, it would oscillate more quickly than the molecule B, 
which is the most distant. But by reason of the connexion 
of the system, the velocity of A will be abated, while that 
of B will be accelerated, and there will necessarily be an- 
other point, C, between these two extreme points, whose 
motion will neither be accelerated nor retarded. This 
point, and all those at the same distance from the axis of 
rotation, will oscillate as though they were free. This is 
called the centre of oscillation. 

We therefore conclude that a composite pendulum exe- 
cutes its oscillations in the same time as a simple pendulum, 
whose length is the distance from the centre of suspension 
to the centre of oscillation. 

But yet there is a difference : a simple pendulum having 
no resistance to overcome, moves indefinitely without any 
variation of the amplitude or duration of its oscillations ; 
whilst in a composite pendulum, the friction of the axis of 
suspension against the supports with the resistance of the 
air which it is obliged to displace, gradually diminishes its 
velocity, and brings it sooner or later to a state of rest. But, 
happily, despite the diminution which the amplitude of the 
oscillations of the composite pendulum continually experi- 
ences, their duration remains the same when these oscilla- 


tions are small. This is evident, as the resistance of the 
air and the friction lengthens the descending semi-oscillation 
in a quantity equal to the diminution of the ascending 
semi-oscillation by the same causes. The duration of the 
whole oscillation remains the same, and the laws contained 

in the formula t=-*\/ — are appliable to the composite 

pendulum, provided that we understand by Z, the length of 
this pendulum, the length of the simple pendulum to be 
synchronous with it. 


1st. Measure of the force of gravity, — " "We deduct from 
the above formula," says M. Pinaud, in his programme 

of a course of physics, "the following value: — q ==.—=-? 

To calculate g, it is only necessary to know the length of 
the pendulum and the time of an oscillation. These mea- 
sures have been obtained with great precision by Borda, of 
Paris. He first obtained the length, I, by measuring with 
a micrometrical apparatus the distance from the axis of sus- 
pension to the centre of oscillation. To obtain the dura- 
tion, t, of an oscillation, it is necessary to count the num- 
ber of oscillations made by the pendulum in a given time, 
and to divide this time, expressed in seconds, by the num- 
ber of oscillations. But as this counting would be very 
laborious, and liable to many errors, Borda eludes these 
inconveniences by the method of coincidences. He places the 
pendulum near a well-regulated clock, the balance of which 
beats faster or slower, and at a given instant sets both in 
motion. From the first oscillation they cease to go together, 
and at the end of a certain time they again coincide at the 
point of departure. The number of pendular oscillations 


during this interval of the two coincidences must then be 
counted; this number will be constant. It will henceforth 
suffice to count the number of coincidences in order to 
deduct the total number of oscillations effected in a time 
marked by the clock, and consequently the duration of each 
of them. This method is susceptible of extreme precision. 
We thus find that g = 32 feet. We thence conclude 
that at Paris a heavy body, falling in a vacuum, passes 
over 16 feet in the first second of its fall. The num- 

ber g being known, if in the formula g=T-^ _ we sup- 
pose t = 1, we can calculate the length of a pendulum 
beating seconds in the latitude of Paris; we find I — 
39-12 + inches. 

2d. Variation of the Force of Gravity with the Latitude. — ■ 
The force of gravity from the surface of the earth varies 
with the latitude, increasing from the equator to the poles. 
This may be verified by transporting the same pendulum 
to various parts of the globe, and measuring in each place 
the time of the pendulum oscillation, or the number of 
oscillations made in a given time. In truth, if the intensity 
of weight augments, the duration of the oscillation dimi- 
nishes, according to the third law. Now the fact has been 
well established by numerous observations, that the same 
pendulum oscillates more slowly at the equator than in the 
polar regions, and that the oscillation becomes slower as it 
approaches the equinoctial line. 

What are the causes of this diminution of the force of 
gravity in going from the poles to the equator ? There are 
two : — 1st, the flattening of the terrestrial globe ; 2d, the 
centrifugal force. 

The earth rises at the equator and flattens at the poles. 
According to astronomical calculations, the radius of the 
equator exceeds the radius of the poles about fifteen miles. 

142 the watchmaker's manual. 

One of the principles of mechanics is that the attraction of 
a spherical or spheroidal mass upon a point placed at its 
surface, is the same as though the whole attracting mass 
were concentrated in its centre. The points which are at 
the equator, being farther removed from the centre of ter- 
restrial attraction than are those at the poles, should there- 
fore be less strongly attracted, since the weight decreases 
as the square of the distance augments. The force of 
gravity is only constant in reality when very near the sur- 
face of the globe ; when the distance is comparable to the 
terrestrial radius, the gravity diminishes as the square of 
the distance increases. This decrease may be sensibly per- 
ceived at the summit of high mountains. 

In the second place, the earth turns upon its axis once a 
day ; its centrifugal force is increased in each parallel circle 
in proportion to the greater radius of the parallel, and as the 
equator is the greatest of all, the centrifugal force is there 
at its maximum. Besides, the centrifugal force at the equa- 
tor is directly opposed to the action of gravity, as it acts in 
conformity with the prolongation of the terrestrial radius or 
of the vertical. In the other parallels, the direction of the 
centrifugal force, which acts according to the prolongation 
of the radii of these circles, is inclined to the vertical in 
proportion as the circle approaches the poles. But a part 
of these forces — the vertical component — then resists the 
gravity, and it diminishes as the inclination increases. 

At the poles, the centrifugal force has no effect. It has 
been calculated that if the earth turned seventeen times 
faster at the equator, the centrifugal force would equal the 
gravity, and bodies would lose their weight. 

The pendulum is not only of service in demonstrating that 
the force of gravity decreases in going from the poles to the 
equator, but also in determining the law of this diminution, 
and consequently, the flattening of the globe and its figure. 


The laws of the pendular movement are very important, 
as they find an application in numerous physical pheno- 

The isochronism of the oscillations of the pendulum forms 
the most exact and valuable means for the measure of time, 
and we shall now regard it in this light. 



Galileo first conceived the idea of measuring time by the 
oscillations of the pendulum, but we owe to Huyghens the 
application of this pendulum to clocks in order to obtain 
the regularity of these movements. He projected the means 
of making it serve as a moderator to the trains of machines 
designed to measure time ; we will give a brief abstract of 
his laws for the pendulum. 

" It has been demonstrated, 1st, that pendulums de- 
scribing arcs of any kind, perform their vibrations in times 
which are to each other as the square roots of the lengths 
of the pendulums. 

" 2d. That the lengths of the pendulums are to each other 
as the square of the time of vibration in each. The longer 
the pendulum, the more time remains for its vibrations ; so 
that if the lengths of two pendulums are to each other as 4 
to 1, the times of vibrations will be to each other as 2, the 
square root of 4, and 1, the square root of 1 of these lengths. 
It therefore follows that while the pendulum 4 makes one 
vibration, the pendulum 1 will make two. It is evident 
then, that if these pendulums beat during the same time, 
the numbers of the vibrations will be to each other as 1 is 
to 2 ; that is conversely as the square roots of the lengths." 

For the convenience of artisans, tables have been formed 

144 the watchmakek's manual. 

in accordance with, these principles, indicating the length 
to be given a pendulum to beat in an hour a given number 
of vibrations, determined by the wheel work, or to show 
the number of vibrations which should be beaten, the length 
of the pendulum being given. 

To form these tables, it is first necessary to determine the 
length of a pendulum beating seconds ; that is, making 
3,600 vibrations per hour. The celebrated Huyghens fixed 
this at 3 feet, 8 lines, and 50 hundredths of a line by rule. 
The academicians of Mairan and Bouguer have found, from 
repeated experiments, that the length, of a simple pendulum 
beating seconds, at Paris, should be 3 feet, 8 lines, and 57 
hundredths of a line by rule ; that is 7 hundredths longer 
than that of Huyghens ; an important, though apparently 
very slight difference. 

At the time of the establishment of the metrical system 
in France, the commission of geometricians who were 
charged with this work, verified the preceding calculations, 
and discovered an error therein. The accuracy of the 
instruments, and the improvements which had been intro- 
duced since these calculations were made, gave them facili- 
ties for rectifying the operations, and they fixed the length 
of the simple pendulum at 3 feet, 8 lines, and 559 thousandths 
of a line, which gives an excess of 59 thousandths over 
Huyghens, and of 11 thousandths over the academicians ; 
a slight difference, yet important to science. 

It may be well to state here that the length of pendu- 
lums beating seconds is not the same; 1st, in all coun- 
tries ; being longer at the poles and shorter at the equator, 
this variation in each degree of latitude is caused by the 
centrifugal force which, impels the terrestrial globe in its 
diurnal rotation : 2d, in all places elevated above the sea ; 
as the weight varies in places removed from the centre of 
the globe where attraction is exercised. 


We will conclude this chapter by the description of an 
ingenious method invented by Berthoud for regulating 
the length of a pendulum by the movement of the clock 
when a slight motion of the screw-nut which supports the 
pendulum or ball has made it too long or too short. He fixes 
at the bottom of the ball, by two screws, a piece of brass 
(Fig. 6, PL Y.), whose upper part, A, encircles the thick- 
ness of the ball ; the rod, L, is cylindrical, and is pierced 
through with a cylindrical hole, into which the end of the 
pendulum passes freely and without play. This is turned 
cylindrically, and is terminated by a screw, upon which the 
screw-nut, M, and the counter-nut, N, move. A cylindrical 
plate of brass, 0, slides easily, and without play, upon the 
cylinder, L, and is fixed at the proper point by the adjust- 
ing-screw, P. By raising or lowering this cylindrical 
round-plate, the centre of oscillation of the pendulum is 
imperceptibly changed, and the divisions marked on this 
cylinder direct the regulation. The screw-nut, M, is only 
used when the extremity of the cylinder has been reached 
without obtaining the desired regularity. 

This is now effected by a small weight, placed on the 
rod midway between the point of suspension and the pen- 
dulum-ball, and held in its place by friction ; this weight 
is adjusted by trial. 



The authors who have written on horology, and the 
learned mathematicians who have written on mechanics, 
have all given rules, more or less simple and easily exe- 
cuted, for determining the number of teeth of wheels and 
leaves of pinions which the different parts of the same 
machine should have in order that the whole train may 
cause the last of these wheels to make a given number of 
revolutions during one or several turns of the first. We 
do not intend to describe here all the methods which have 
been proposed, for we do not write for those scientific artists 
who are familiar with all the intricacies of calculation. 

We know of no process more simple than that indicated 
by Camus in his Elements de Mecanique Statique, Book XI., 
and shall therefore take him as a guide in our treatment of 
this subject. We shall now occupy ourselves with the 
solution of some problems which an artisan may have occa- 
sion to resolve in ordinary horology. 

Fundamental Principle. 

Whether a wheel carries a pinion or a pinion a wheel, 
the number of revolutions of the wheel, multiplied by 
the number of its teeth, is equal to the number of re vol u- 


tions made in the same time by the pinion, multiplied by 
the number of its leaves; so that the number of synchronal 
turns of the wheel and the pinion are conversely propor- 
tional to the number of their teeth. 

Let us suppose the number of teeth of the wheel, A, and 
of the pinion, F, to be represented by the capital letters 
A, F, and the number of their synchronal turns by the 
italics a,f. 

"We wish to demonstrate that axA=/xF, and, con- 
sequently, that a :f: : F : A. 

" First, The number of the teeth of the wheel being 
represented by A, the wheel will work into the pinion at 
each revolution a number of teeth represented by A. Thus, 
while the wheel shall make a number of revolutions ex- 
pressed by a, it will work into the pinion a number of teeth 
represented by a x A. 

" Second, As F represents the number of leaves of the 
pinion, this will work a number of leaves expressed by F 
into the wheel at each revolution. Thus, while the pinion 
shall make a number of turns expressed by f, it will work 
into the wheel a number of leaves expressed by/xF. 

" But while the wheel and the pinion are making their 
simultaneous' revolutions, as many teeth of the wheel will 
work into the pinion as leaves of the pinion will work 
into the wheel. Thus we shall haveaxA=/xF; and 
regarding the two terms of the first member of this equa- 
tion as the product of the extremes, and the two terms of 
the second member as the product of the means of a geo- 
metrical proportion, we shall have a :/: : F : A, as we ad- 

We may conclude from this demonstration that if we 
have a train composed of as many wheels as may be neces- 
sary, with a like number of pinions working successively 
into each other, the same principle will be applicable to 

148 the watchmaker's manual. 

every part of the train. Let us suppose four wheels, desig- 
nated by the capital letters A, B, C, D, with four pinions 
designated by the capitals F, Gr, H, I; representing the 
synchronal revolutions of the wheel A, and of the pinions 
F, G, H, I, by the italics a, f, g, A, i ; we shall have accord- 
ing to the preceding proposition for each wheel working 
into its corresponding pinion, the four following propor- 
tions : — ■ 

1st. a : / : : F : A ; 

2d. f:g::Gr:B; 

3d. g : h : : H : C ; 

4th. h:i:: I : D. 

By multiplying these four proportions in order; that is, 
the antecedents of each proportion together, and also the 
consequents, according to arithmetical rules, and suppress- 
ing in the antecedents and the consequents of each propor- 
tion those terms which are common to both, the terms of 
the first member will be reduced to two, a, and i } and we 
shall have the following composite proportion : — 

a : i : : FxGrxHxI: AxBxCxD, whence we deduce 

the equation, axAxBxCxD=ixPxGxHxI, and, con- 

,, . axAxBxCxD m , , „ , 

sequently, i = == — ^ — ^ — =, . lne number oi revolu- 

H J ' FxGrxHxI 

tions, ij of the last pinion, I, will therefore be equal to the 
number of revolutions, «, of the first wheel, A, multiplied 
by the product of the number of the teeth of all the wheels, 
and divided by the product of the number of leaves of all 
the pinions ; so that if we make a—\ ; that is, if we con- 
sider that the wheel A makes but one turn, the result of 
this equation will give the number of turns, i, which the 
pinion, I, will make while the wheel, A, is performing its 

" It also follows from this example, that if the train 
which is to be executed should have one or two wheels, and 


as many pinions more or less than the four supposed in our 
example, it will only be necessary to add or subtract the 
required number from the four proportions, so as to have 
but one for each wheel and each pinion." 

This general rule is applicable to the calculations of all 
trains which ordinary watch-making may require, as we 
shall prove in the following examples. 


To find the number of teeth and leaves required for the wheels 
and pinions of a clock or watch beating seconds ; that is 
3,600 vibrations per hour. 

Custom has fixed the number of the wheels and pinions 
in watches to be four, thus styled — 1st, the large centre- 
wheel which makes one revolution per hour ; 2d, the small 
centre- wheel ; 3d, the crown-wheel ; 4th, the escapement- 
wheel. We will designate these wheels by the capital 
letters A, B, C, D ; the wheel A works into the pinion Gr, 
which carries the wheel B ; this second wheel works into 
the pinion H, which carries the wheel C ; this third wheel 
works into the pinion I, riveted with the wheel D ; this 
fourth wheel, D, does not work into any pinion, but is 
checked in its movement at each tooth by the escapement- 
piece, whose construction and effects must be considered. 

Three kinds of escapements are now in use in clocks and 
watches — 1st, the recoil-escapement, also known by the 
name of balance-wheel escapement ; 2d, the dead-beat es- 
capements, which are very numerous; 3d, the detached 
escapements. In the first two classes, each tooth of the 
escapement-wheel produces two vibrations when the wheel 
is simple ; that is, when the teeth of the wheel are cut upon 
its circumference as in a cog-wheel ; but each tooth pro- 


duces but one vibration when these teeth are placed alter- 
nately upon the two surfaces of the same wheel, as in the 
pin-escapement of Lepaute, and the detached-escapement 
of Le Normand. 

The detached escapements, such as the Arnold-escape- 
ment, and the escapement of constant force, permit but one 
tooth to pass during two vibrations. It is therefore import- 
ant, in the solution of this and the following problems, to 
know the nature of the escapement to be used, as this is an 
element which should enter into the calculation. We are 
therefore compelled to give two solutions,, each of which 
applies to one of these cases. 

First case ; that is, when each tooth produces two vibra- 
tions. According to the general principle, the first member 

of the equation which we seek will be — ~ ^= — - — , 

^ GxHxI 

but as each tooth of the wheel D, produces two vibrations, 

we should multiply D by 2, when this first member becomes 

— „ -r-r — ^ — ; but, bv a condition of the problem, the clock 

should beat 3600 vibrations; this member should therefore 
become the second member of our equation, and we shall have 

— ~ — ^p — = — 8600. By dividing the second member bv 
GrxHxI J ° 

2 to clear D of its co-efficient, and transposing the divisor 

GxHxI into the second member, by means of multipli- 


cation, we shall have AxBxCx D ==— — x Gr x H x I, and 

executing the division we shall have AxBxCxD^ 
1800xGrxHxI. As we are at liberty to give to each 
pinion the number which we wish, we will choose 10 for 
each of them, in order to secure the best gearings ; this 
transforms our equation thus : — 

AxBxCxD = 1800x 10x10x10. 


The only point now in question is the decomposition of 
these numbers into their separate factors, by dividing them 
by 2 as far as possible, then by 3, and finally by 5, as these 
are the smallest numbers which can divide them. By 
dividing 1800 by 2, I obtain for a quotient 900, which I 
divide again by 2 and obtain 450, which I also divide by 2, 
obtaining 225, which is no longer divisible by 2 ; this divided 
by 3 gives 25, which is only divisible by 5 ; the quotient 
5 divided by 5 gives 1, which indicates that the operation 
is exact : each of the three pinions also gives me 2 and 5, 
all of which divisions I write on the same line — 2, 2, 2, 3, 3, 
5, 5, 2, 5, 2, 5, 2, 5, — which are the factors to be used. 

When the escapement is a balance-wheel, we are limited 
in the number of teeth, which should be uneven, and by its 
size. This limit extends from 11 to 17. But not having 
any number which can form one of these four products in 
the factors found, we take 3 and 5, which give 15, for the 
number of teeth of the escapement- wheel, D. It then only 
remains to divide the other factors into three parts, the 
products of which will give the number of teeth required 
for the wheels A, B, and C. 

These we divide in the following manner : 

1st. 2 X 2 X 3 X 5 = 60 for the wheel A ; 
2d. 2X5X5 =50 for the wheel B; 
3d. 2X2X2 X 5=40 for the wheel C. 

Our train therefore is thus composed : 

Teeth. Pinions. Eevolutions. 




















But, as each tooth of the wheel, D, gives two vibrations, by 
multiplying 120 revolutions by 30, which is twice the num- 

152 the watchmaker's manual. 

ber of the wheel D, we have 3600 vibrations for a product, 
which is the number required. 

Second Case. — When the escapement-wheel permits but 
one tooth to pass in two vibrations. The wheel, D, should 
have no co-efficient in the first member of the primitive equa- 
tion, and consequently the first term of the second member of 
the equation should have no divisor. It will therefore stand 
thus : — A xBxCxD= 3600 x 10 x 10 X 10, and operating as 
in the first case, we shall obtain 2 for a factor besides those 
which we have already noticed. Still leaving the escape- 
ment-wheel with 15 teeth, and giving 10 leaves to each 
pinion, we shall have for the numbers of the teeth of the 
wheels, A=80; B = 60; C=50; D = 15. In executing the 
above operation, we will find that the wheel D makes 240 
revolutions during one revolution of the wheel A ; and by 
multiplying 240 by 15, the number of vibrations which the 
wheel D causes the regulator to make by each of its revo- 
lutions, we shall find as before 3600 vibrations per hour for 
our product. 

Essential Note. — When half the teeth of the escapement- 
wheel are on one surface and half on the other, as in the 
pin -escapement of Lepaute, the calculation can be performed 
in two ways. 1st, If we only count the teeth upon one 
surface, we execute it, as in the first case, by giving the 
co-efficient 2 to the wheel D. 2d, If we add the numbers 
of teeth on both surfaces, or multiply the number on one 
surface by 2, we perform the operation, as in the second case, 
without giving any co-efficient to the wheel D. 

This is a general and unexceptionable rule, whatever 
number of vibrations the clock may be required to beat. 
The number of vibrations now in use for watches is 
14,400 for four vibrations per second, or 18,000 for five 
vibrations per second. It is only necessary therefore to 
substitute for 3,600, one of the two numbers we have just 


given, or any other that may be wished, and to change the 
given number of the pinions to that which may be adopted. 

The same calculation and the same process should be 
followed in order to find the teeth of the wheels and 
pinions which should precede the great centre-wheel, when 
the clock is required to run longer than thirty hours, as 
eight days, a month, a year, etc. We multiply the proposed 
number of days by twenty-four, the number of hours in 
each day, and form an equation. Let us suppose that we 
wish it to run eight days ; this will give 192 hours, or 192 
turns which the minute-wheel, A, should make during one 
revolution of the wheel P ; we shall thus form this equation : 
PxQ, etc.=:192x 16x12, etc., provided that in this case 
we wish to have two wheels and two pinions. 

It remains for us to give some ideas on the application 
of this rule to clocks whose regulator is a pendulum. But 
two cases present themselves, and the solution of two prob- 
lems will suffice to explain this double question ; these are 
reduced to a simple formula, in order to bring them back 
to the general rule. 


To find the number of the teeth of the wheels and the leaves of 
the pinions of a clock whose vibrations are determined by the 
height of the space in which the mechanism is inclosed. 

The whole question is reduced to finding the length of 
the pendulum, because when this length is once known, the 
number of vibrations which the clock beats per hour may 
be easily found by the processes which we have before de- 
scribed. Thus, the height of the frame exactly measured 

being 9 lines from the point of suspension, we ascertain 


154 the watchmaker's manual. 

that it will beat 7,700 vibrations per hour, which suffices to 
include this problem in the solution of Problem First. 


To find the number of teeth of wheels and leaves of pinions of 
the striking-work of an ordinary clock. 

An ordinary clock demands a few special considerations. 
It is composed of five wheels and pinions ; the first wheel 
being fixed on the barrel which contains the spring. The 
second wheel carries the notch-wheel, and should make one 
revolution in twelve hours. As it should strike at every 
half-hour, the clock will consequently strike ninety times 
in twelve hours. It should therefore carry ninety pins ia 
order to produce the same number of strokes, but as these 
pins would otherwise be too near each other, they are car- 
ried by the third wheel, which is called the pin- wheel. This 
wheel carries ten pins, and should consequently make nine 
turns while the second makes but one. 

The following wheel, which is the fourth of the train, is 
called the locking or ballast-wheel, this carries a single pin, 
and makes one revolution at each stroke of the hammer. 
It is also called the check- wheel, because it stops the train 
when the strokes of the hammer, which are determined by 
the notches of the notch-wheel, are finished. The next 
wheel, and the pinion of the fly which terminates this train, 
have no other function than that of slackening the course 
of the train in order that the strokes of the hammer may 
not be too fast to be counted. 

The numbers generally adopted are as follows : — for the 
barrel- wheel, 84 teeth ; second wheel. 72 teeth, pinions, 12 ; 
third wheel, 50 teeth, pinions, 12, 10 pins ; fourth wheel, 


54 teeth, pinions, 6, 1 pin ; fifth wheel, 48 teeth, pinions, 
6 ; pinion of the fly, 6 leaves. 

It is evident that by calculating from these numbers the 
number of revolutions which the pinion of the fly should 
make during one turn of the first wheel, we will find that 
it revolves 30,240 times, and that it makes 72 turns at each 
stroke of the hammer, or during one revolution of the 
locking-wheel. The velocity of the last pinion may be 
increased or diminished by making the wings of the fly 
narrower or broader. 

As the first wheel of 84 teeth makes one revolution in 
three days and a half, according to the given numbers ; it 
will be sufficient to have a spring making five turns to 
cause the clock to go for seventeen and a half days without 



We do not propose to describe here all the inventions 
which have been made in horology, the most of which 
have figured in the various Exhibitions of Art, but shall 
only cite a few which are especially remarkable. 

Watch of Bock- Crystal. 

A watch was placed in the Exhibition of 1827 by M. 
Rebiller, the wheels and bridges of which, and the caps of 
the case were of rock-crystal, a transparent substance of a 
hardness but little inferior to that of the precious stones. 

The artist presented this piece to the Societe oV Encourage- 
ment; and we transcribe the description of it made by M. 
Erancoeur to the Conseil oV Administration. 

" When we consider the difficulty of working rock-crystal 
and precious stones, and think of the extreme delicacy of 
the parts of a watch so small that it can be worn on a 
lady's neck, we can hardly conceive how M. Rebiller could 
have succeeded in executing a work of this kind. It is 
difficult to imagine the method by which he cut a thread 
for screws into so hard a substance as rock-crystal. This 
watch is a work of infinite patience and skill, as well as an 
ornament of remarkable elegance. 

" The difficulty of execution gives this watch so high a 
price that it cannot be regarded as an article of commerce, 


but it is a marvel of patience and art, worthy the attention 
of connoisseurs. It possesses no inventive merit, but much 
skill has been required to succeed in cutting a screw in crys- 
tal, in inserting the jewels into a material so difficult to work, 
and in making the wheels and the balance of crystal, and 
the escapement-piece with the bridge which supports it of 
sapphire. M. Eebiller assures us that this piece will go 
with almost as great regularity as a chronometer ; this he 
attributes to the fact that the balance is of crystal, that 
it is moved by a spiral-spring of gold, and that these sub- 
stances are very slightly affected by the temperature. We 
have not verified this assertion, as it would have been ne- 
cessary to submit the watch to tests, and we feared by some 
accident to spoil so beautiful a work." 

We are told that M. Eebiller has added a chain, key, and 
seal, made from a single piece of rock-crystal, to this watch. 

Repeaters without the Small Train. 

The essays at the manufacture of repeaters without a 
small train date back many years. In 1778 a movement 
whose dial-work produced this effect was invented by a skil- 
ful artisan of Geneva ; this was acknowledged by watch- 
makers to be the first repeating-watch without the small train. 
In 1807, M. Berolla, a watchmaker of Besancon, took a 
patent for invention for a repeater without the small train. 

In 1817, N". Yincenti executed a repeater the dial- work 
of which differed from any before known. 

In 1820, M. Laresche, a Parisian clockmaker, took out a 
patent for the invention of the dial-work of a repeating- 
watch without the small train ; these inventions we shall 

1st. Repeater without the small train, executed at Geneva in 

158 the watchmaker's manual. 

The large pillar-plate is grooved with, a circular cavity 
beneath the dial, and eccentric to the pillar-plate, by a 
width of about two lines, and a depth of half a line. 
The whole diameter of this cavity is the seventeenth of 
the diameter of the pillar-plate, and this circle is in con- 
tact with the circle of the pillar-plate on the side where the 
figure 12 is marked on the dial. A ring of steel is lodged 
in this grooving ; this is fixed upon the pillar-plate by three 
steel keys, which prevent it from springing up. Fifteen 
ordinary teeth are made on the edge of this ring, and in 
the outer part on the side of the pendant. On the left side, 
towards the figures 7-9, are twelve cogwheel teeth. 

The rest of the dial- work is very simple ; a snail of the 
quarters with its surprise placed as usual on the minute- 
hand pin ; an hour-snail with its star- wheel ; a catch with 
its spring ; a motion of the quarters having but three teeth 
at the extremity of one of its arms, with its spring as usual ; 
and a single hammer. A steel rod carries a pinion of 12 
at its inner extremity, and a large knob of the same metal 
as the case at its outer extremity, to which the ring which 
holds the chain by which the watch is suspended is fas- 
tened by a transverse screw ; this serves to put the dial- 
work in action. 

When the hour is to be repeated, the knob is turned to 
the left ; the pinion of 12 works into the rack and forces 
the arm which it carries to advance towards the figure 9 ; 
this advances until it encounters the hour-snail. In this 
movement, two effects are produced — 1st, a pin placed upon 
the movable steel ring removes it from the motion of the 
quarters, which, becoming free, goes to rest by its second 
arm on the quarter-snail, towards which it is incessantly 
urged by the spring that impels it ; 2d, it passes as many 
of the teeth of the rack before the knob of the hammer as 
there are hours indicated by the snail. Then, by turning 


the knob in the opposite direction, the movable ring is 
brought back to its original place, and the hours strike ; 
after a short interval, the quarters strike in the same man- 
ner. This must be turned slowly, in order that the strokes 
may be distinctly counted. 

We would suggest the practicability of adding two im- 
provements to this construction ; viz., of putting in an all- 
or-nothing -piece, and of causing it to strike double quarters. 
This will be easily understood by watchmakers ; the hour- 
snail must be slightly displaced in order to put in place 
the all-or-nothing -piece ; a motion of the quarters must be 
made in the usual manner, and a second hammer added. 

2d. Repeater without the small train, by M. Berolla. 

" The exterior of the watch resembles other watches, 
except in a knob placed above the pendant, which mus.t be 
turned to the left to make it strike ; this strikes the hours 
marked on the dial in proportion as it is turned. In the 
interior, the movement is precisely like that of an ordinary 
watch without the repeating-train, except that there is a 
single hammer placed in the frame which strikes against a 

"The dial-work' is composed of a rack for the hours and 
another for the quarters ; these cause the movement of the 
hammer. That of the hours connects with an endless screw, 
which is adjusted to the knob which we have mentioned, 
and which, by a mechanical movement, causes the rack of 
the quarters to move at the same time. There is also a 
star- wheel for the hours with its snail, as well as a motion 
of the quarters, but these pieces do not differ from those of 
ordinary repeaters." 

3d. Repeater of M. Vincenti. 

The movement has two trains moved by the same spring ; 
there is therefore but one barrel to which the chain that 
conducts the fusee is attached. The barrel-arbor carries a 


steelplate, cut in cogs, upon which a great- wheel with the 
click and spring is mounted, so that the spring aids the 
chain by its extension, and the click and spring work by 
its centre ; this wheel is constructed on the barrel-arbor in 
the same manner as the first wheel of the small train of a 
repeater. The rest of the small train is formed of wheels 
larger than those of ordinary repeaters. 

The case does not differ essentially from others. 

A longitudinal cleft is made between the figures 12 and 
3, and parallel to the edge of the rim, into which a small 
projecting button enters. When the repeater is to be struck, 
the knob is pushed with the nail towards the figure 3. Two 
effects are simultaneously produced — 1st, the arm of the 
piece which serves as a rack comes to rest on the hour-snail, 
and fixes the number of strokes for the hours ; the all-or- 
nothing-piece recoils, the motion of the quarters, becoming 
free, falls upon the quarter-snail, and the train acts ; 2d, at 
the same time in which this takes place, the spring is wound 
up far enough by the same knob to cause the hours and the 
quarters to strike. The all-or-nothing-piece, and the other 
pieces of the dial- work, differ from those of ordinary re- 

4th. Repeater with outtrain, by M. Laresche. — M. Laresche, 
a Parisian clockmaker, took a patent for invention, for five 
years, in 1820, for a new dial- work of a repeater without 
the train. This mechanism seems to us to be too compli- 
cated, and we do not regard its effect as certain, which is 
probably the reason that the author has not renewed his 
patent. We have never seen any of his watches in com- 
merce, and shall not, therefore, give the description; it may 
be found in Volume xiii. of Breve s d } invention expires, p. 43. 

Chronometrical Index. 
This machine, which formed part of the exhibitions of 


1819 and 1823, was invented by us more than forty years 
since. We communicated it to the late M. Peschot, who 
chaaged the name which we had given it, and which per- 
fectly expressed its functions — cJironometrical index — to that 
of chronometer, which only signifies the general measure of 
time, being applicable to all clocks, and which is now 
applied to an especial time-keeper. 

We explained the principle on which our construction is 
based in a memoir which may be found in Yol. xv., p. 248, 
of our Annales de V Industrie nationale et etr anger e ; but did 
not enter into the details of its execution, as our only design 
was to render an account of a suit against an infringer, and to 
prove that the construction which he had adopted, although 
differing essentially from our own, was based on the same 
principle. The tribunal decreed that the principle belonged 
to us, and condemned the counterfeiter. 

Although we can use a movement of any watch, yet we 
shall succeed much better by constructing a movement 
expressly for this, as it is important to have the exterior 
surfaces of both pillar-plates entirely free. 

Those who saw, in 1820, '21 and '22, the arrows which 
marked the hour upon the two opposite mirrors of the 
Opera lobby, know that the movement of the watch that 
produced this effect was concealed in a case placed between 
the opposite feathers at the point of the arrow. Our move- 
ment is not fixed to this case ; it is only carried there by its 
centre, around which it can turn freely ; finishing its revo- 
lution in twelve hours, or in one hour, at will, as we shall 
presently show. 

As it is necessary to displace the arrow in order to wind 
the watch, the square of the remontoir must be placed on 
the side of the small pillar-plate as in the English watches ; 
many obstacles oppose the placing of it upon the large 
pillar-plate, the greatest of which is. that of encountering 


the square which presents itself at the hole of the dial, as 
this square turns around the centre of the watch along with 
the whole of the movement, while the dial does not move. 
The train possesses the advantage of running eight days 
without winding. It is well to adjust a dead-beat escape- 
ment to this ; our escapement, that of Seb. Le Normand, 
was invented for this movement. A verge escapement can 
be given it, but it will then be necessary to add a fusee on 
our construction for replacing the fusee which we have 
described. Let us suppose that there is no fusee ; when the 
caliber is traced, a diameter is traced passing through the 
middle of the hole of the barrel. The axle of the escapement- 
piece should fall in this line. The balance turns horizontally 
above the frame and perpendicularly to the surface of the 
pillar-plates. "We shall show the advantage of this arrange- 

In our system, although our movement turns around the 
axle of the great centre-wheel, it never changes its respective 
position in relation to the diameter traced on the caliber ; 
so that this diameter constantly maintains a vertical position, 
while the barrel, which serves as a weight to put the lever 
in motion, is always at the bottom towards the figure 6 ; and 
the balance is always at the top towards 12. At each 
vibration of the balance, the movement inclines to turn, but 
at the same time the centre of gravity of the balance, which 
should tend to depart from the vertical direction, forces the 
lever to turn a little, in order to bring it back to this vertical 
position ; by this means it is prevented from moving from 
its place, and is only transported in a circumference of a 
circle whose centre is the axle which supports the lever. 
But all the parts preserve the same position in respect to 
the vertical diameter of which we have spoken, which is 
continually carried on the same plane in the orb which it 
passes through, thus resembling the movement of the earth's 


axis. The watch in the chronometrical lever is always 
stationary like the movement of a mantel clock ; this 
contributes much to its regularity. 

The frame of the train should be enclosed by four brass 
bands of five lines in width; these form a frame in the midst 
of which the movement is suspended, which can turn freely 
upon the two pivots of the large centre-wheel, as we shall 
explain. This frame is fastened to the arrow. 

The circumference of one of the pillar-plates, it matters 
little which, should be cut in cogs like a wheel of the click 
and spring-work of a watch, and a click with its spring must 
be placed in each of the pillars of the frame just mentioned 
to form a click and spring- work in this part. This precau- 
tion is important, as, without it, when the spring is wound, 
the movement turns and its regularity is disturbed ; making 
it necessary to reset it, and risking the breaking of several 
pieces. If we take care in adjusting the two click and 
spring works, to prevent them from stopping both at the 
same time, we shall obtain the effect of double teeth to the 
wheel. The teeth of the cog-wheel should be turned in a 
contrary direction to those of the remontoir, as their effect 
is opposite. The click and spring-work should yield while 
the watch goes, and stop while it is wound. 

The frame of the movement should be suspended by the 
fixed frame ; the axle of the great centre-wheel carries 
a pivot at each end which should turn freely in the two 
opposite cross-bars of this frame. But, before describing 
this part of the mechanism, we will explain what we mean 
by the large and small pillar-plate, since, in this construc- 
tion, their diameter and thickness are the same. This 
distinction is necessary on account of the pieces which are 
on the cross-bars of the frame, and which are different, in 
order to impart to them distinct and separate movements. 

We shall call the plate on which the pillars are riveted 

164 the watchmaker's manual. 

the large pillar-plate, as in ordinary watchmaking ; upon 
the surface of this we place the dial and hands ; the other 
we designate as the small pillar-plate. 

A small hole is pierced in the midst of the length of the 
cross-bar, on the side of the large pillar-plate ; upon this 
hole and beneath the same cross-bar a bridge, fastened by 
two screws and two chicks, is placed ; a hole, exactly cor- 
responding with that of the band of the frame, is then 
marked with the pitching-tool. This hole should carry one 
of the pivots of the centre- wheel. A corresponding hole is 
made with the same tool in the cross-bar of the opposite 
piece. In this hole, or in a piece which replaces it, the 
other pivot of the large centre-wheel revolves, which, 
carrying no minute-hand pin, etc., does not need a long 
rod beyond the pillar-plate. 

The barrel has 96 teeth, working into a pinion of 12, 
carried by the second wheel, called the time-wheel, which has 
80 teeth, and works into a pinion of 10 which carries the 
large centre-wheel. The barrel making one turn in 61 
hours, the second finishes its revolution in 8 hours, while 
the third revolves in one hour. The spring with three and 
a half turns will make the watch go during 224 hours ; 
that is, more than nine days. 

The numbers for the other wheels following the large 
centre- wheel, as well as those for the leaves of the pinions, 
can be found from the rules which we have given in 
Chapter Ninth. When the number of vibrations which it 
should beat during an hour has been fixed — we will sup- 
pose that it should beat 14,400 vibrations per hour — and 
our escapement has been adjusted to it, by giving six 
leaves to each of the three pinions, and twenty teeth to 
the escapement- wheel, which is one vibration for each 
tooth, we shall find the number of the teeth of this train as 
follows : — 





Large centre-wheel 



Small centre-wheel 

.- . 54^ 



Crown-wheel . . . 




Escapement- wheel 




In order, that the end of the arrow may make its revolu- 
tion in twelve hours, the rod of the second wheel of 80 teeth 
passes through the small pillar-plate and is filed square 
outside of this plate. A pinion of 12 teeth is solidly 
adjusted upon this square, which works into a wheel of 18, 
placed in the hole bored in the middle of the frame-band, 
on the side of the small pillar-plate, and inside of it ; that 
is, on the side of this pillar-plate, a pinion of 16 and a 
wheel of 24 teeth, or a pinion of 26 and a wheel of 30 teeth 
may be used instead of these, or any other numbers bearing 
the same proportion to each other. In all cases, the wheel 
should be riveted on the cross-bar, and the leaves of the 
pinions should be inside, and thick enough always to work 
into the wheel. * 

It is evident that since the arbor of the time-wheel 
revolves once in 8 hours, it will make one and one-third 
turns before its pinion of 12, of 16, or of 20, shall have 
passed through 12 hours, and consequently that the arrow 
will complete its revolution in twelve hours. 

When it is required to turn the arrow in one hour, the 
construction of the train of the movement is not changed, 
but the alteration is effected by the different arrangement 
and numbers of the wheel and pinion of which we have 
just spoken. We know that the time- wheel finishes its 
revolution in 8 hours ; a wheel of 80 teeth is placed squarely 
on the axle of this wheel, and a pinion of 10 is riveted at 
the middle of the cross-bar ; by this means the train will 
turn 8 times while the time- wheel turns once. 

In both cases, a hole is pierced in the centre of the pinion 
or of the wheel, which should be riveted on the cross-bar ; 

166 the watchmaker's manual. 

this hole receives the pivot of the large centre-wheel in 
order that the movement may. be solidly suspended. 

When the arrow is required to finish its revolution in 
twelve hours, no other constructions need be made on the 
side of the large pillar-plate ; in this case, the arrow marks 
the hours on a large glass, and the divisions are large enough 
to permit small divisions to be marked for the minutes, from 
5 to 5, or from 10 to 10. 

But when the revolution should be terminated in one 
hour, a dial should be added, upon which a hand marks the 
hours and minutes if wished. We place this dial on the 
cross-bar which supports the movement; this dial must also 
be adjusted in such a manner as always to present the 
figures 12 and 6 in a vertical position. We have invented 
a method which is not more complicated than the dial- work 
of an ordinary watch, and which produces this triple effect. 

We place a wheel of 48 teeth upon the large pillar-plate 
of the dial, which we fix upon this pillar-plate by three 
screws, and which we elevate two lines by a round plate 
placed beneath, and not extending as far as the teeth. We 
remove the centre of this wheel, and of the round plate, so 
that the rod of the large centre- wheel may not be injured. 
Upon the cross-bar of the frame we place a pinion of 12, or 
any other suitable number, whose pivots are carried by two 
bridges, one of which is placed above, and the other beneath 
the cross-bar. This pinion works into the wheel of 48, 
fixed upon the pillar-plate. The bridge should be near the 
pillar-plate, but should not touch it, as this would stop the 
movement ; this is the reason of the elevation of the wheel. 
The pinion is only placed there to transmit the movement 
from the bottom to the top of the cross-bar, and should 
be long enough to work at the same time into the three 
wheels of which we shalls peak. At the middle of the cross- 
bar, and at the top of the hole which has been pierced in it, 


we fix with a screw a rod of tempered steel, which should 
be exactly perpendicular to the pillar-plates, and in the 
prolongation of the line passing through the two holes of 
the large centre- wheel. Upon this rod we place three con- 
centric wheels, each mounted upon a socket, with space 
enough between them for a slight play. These are of the 
same diameter as the one fixed on the pillar-plate. The 
first has 48 teeth ; the second 52 ; and the third 48. The 
first carries the minute-hand by a socket, the second bears 
the silver or plated brass dial, and the third bears the 
hour-hand. If we give but 48 teeth to the wheel which 
carries the dial, this dial will be an hour in advance at each 
revolution. This effect is analogous to the satellite wheels 
of M. Pescqueur. 

An explanation yet remains to be given, to facilitate the 
execution, and to render regular the movement of the lever. 
One of the two branches is shorter than the other; the 
movement is placed on the shorter branch ; the other should 
produce an equilibrium. This equilibrium is easily obtained 
by placing the arrow on the two points, 3 and 9, and after- 
wards on 12 and 6 ; but this is not sufficient; a small weight 
must be placed under the point of the arrow and in the 
direction of its length, supported by an adjusting screw, so 
that it can be moved with a key, in order to place it nearer 
to or farther from the point of suspension, at will. This 
weight serves to rectify the equilibrium. We perceived the 
indispensable necessity of this, after finishing the construc- 
tion of which we have just spoken. 

We marked the minutes on a large dial of one foot in 
diameter, and, after having placed the minute-hand upon 
the small dial, we perceived a difference of twelve minutes' 
loss in one half of the revolution of the large dial ; which 
loss was exactly counteracted in the second half of the 
revolution ; this made us conclude that the equilibrium was 

168 the watchmaker's manual. 

not exact. We then decided to add the supplementary 
weight, by which we succeeded in regulating the movement 
perfectly, so that the minute hands exactly accorded ; after 
which we removed the little hand of the small dial. 

When the chronometrical lever is to be used against a 
glass which serves as a dial, the glass need not be pierced ; 
a round plate of wood is turned, in whose centre a small 
rod of tempered and polished steel is adjusted, which must 
be strong enough to support the weight of the lever without 
bending, but as fine as possible in order to avoid friction. 
Before this rod is tempered its outer end should be screwed 
to place on it a brass screw-nut, in order to prevent any 
shock from detaching this lever from its place. This screw- 
nut is removed to detach the lever when the watch is wound. 
Three or four round pieces of blotting paper are then cut 
of the same size as the wooden round-plate ; one of these is 
then glued on the glass with powdered quick-lime diluted 
with skimmed milk, and is left to dry ; a second and a third 
paper is then glued with isinglass, and, when the whole is 
dry, the round plate is glued on it with common glue. 
This is left to dry, after which the lever is adjusted on it. 

This lever is a very convenient instrument for obtaining a 
country-clock. A traveller can enclose it in a box and take 
it with him ; it will go during the journey, and, when it 
is ended, he can place it at the centre of a dial arranged for 
it. When he leaves, he can carry it in the same manner, 
and can place it in his house, where it will continue to mark 
the hour without any irregularity. 

New Mechanism of a Repeater invented by M. Lerot. 

The mechanism of M. Lerot is remarkable for its simplicity 
and certainty. The numerous pieces of a repeating watch are 
reduced in it to four, the mechanism of which is very ingeni- 


ous. By adopting this system, these watches can be sold at 
a low price, and the pieces are not exposed to the accidents 
and errors which result when they are much complicated. 

A large steel wheel, whose diameter is a little less than 
that of the dial, and concentric, bears twelve teeth or arms 
upon its circumference, constructed like those of cog-wheels ; 
these arms fall successively on the handle of the striking 
hammer, when they pass in their turn and come in contact 
with it. This wheel, which is wholly independent of the 
movement of the watch, turns by a little crank which is 
placed in the pendant, and whose axle, guided in the direction 
of one of the radii of the dial, carries a pinion ; this pinion 
works into the crown-teeth with which the lower surface of 
the contour of the rim of the large steel wheel is furnished. 

When the hour is to be struck, this crank is turned until 
it encounters a stopwork ; this movement also turns the 
steel wheel, whose arms leave the hammer inactive; the 
crank is then turned in the contrary direction. At each 
turn made in the latter direction, it passes a tooth of the steel 
wheel, and the hammer strikes a blow. The number of 
blows thus struck agrees with the time marked by the hand, 
as a stop- work is encountered which prevents the further 
rotation of the crank. 

The effect is certain, as the stop-work is a ratchet-piece, 
fixed in the minute-wheel-work upon the hour-wheel, so 
that it is impossible for the hammer to strike more blows 
than are indicated by the hand. The quarters are easily 
reckoned by the course which the crank takes after having 
struck the last blow ; this course is represented by the arc 
described until the crank shall have reached its stop-work. 

Two inconveniences attend this mechanism : The first 
consists in the use of the little crank which always projects 
from the pendant of the watch ; the second is the impossi- 
bility of estimating the quarters in the interval which elapses 



between the hours of twelve and one, on account of the 
arrangement of the stop-work, and of the arm which props 
against it. 

But these defects are easily remedied ; the crank can be 
replaced by a milled head turned by the fingers, and the 
stopwork may be broken into a wheel-click to permit it 
to lie flat when the knob is turned in one direction, and to 
rise up when it is turned in a contrary manner. 

Description of a Second- Watch, indicating the precise instant 
of observations, by M. Jacob. 

The mechanism by whose aid the second-hand, after 
having been stopped and again set in motion, places itself 
suddenly on the diameter where it would have been if it 
had not ceased to move, is fixed on the second- wheel. 

The second- wheel is riveted on a pierced pinion , a part of 
which is elongated. A second wheel, very slight, and card- 
ing an axle long enough to pass through the second- wheel, 
is loosely adjusted into the pinion of this wheel ; a ferrule, 
fixed by a screw on the part of the axle of the second wheel 
which extends beyond the pinion, holds the second-wheel 
in a frame on this axle, so that the two wheels can turn 
independently of each other. 

A small arm is placed upon the second-wheel. A rack, 
placed as a satellite on the second wheel, carries a pin which 
is long enough to rest on this arm; a spring presses a 
click upon another pin which may be considered as the 
prolongation of the first, and permits the rack to move 
about half-way round its centre. This rack works into a 
pinion turning freely between the two wheels, so that when 
the spring causes the rack to turn, the latter turns the pinion 
until a rack- detent, which carries the pinion, rests on the 
arm of a very slight spring, placed on the second-wheel ; the 


resistance of this point of support preventing the pinion 
from turning, the rack then turns until its pin meets the 
arm of the second-wheel, the two wheels being thus united 
and placed in frame on the axle of the second wheel, the 
hand carried by this axle marks the second and its frac- 

If the second wheel be checked at the instant of an obser- 
vation by a mechanism which we shall presently describe, 
the second-hand will be fixed on the precise instant of 
observation ; the second- wheel continuing to move and 
drawing along a pinion, this pinion will cause the rack to 
turn, which w T ill push back the click ; and thus, when the 
second wheel is freed, the spring will turn this second wheel 
until the pin of the rack meets the arm of the second- wheel, 
and the second-hand will retake the identical second or 
fraction of a second, which will be marked by the second- 
wheel which has not ceased to move. As each revolution 
of the second-hand is indicated by that of the minutes, the 
second-hand marks the fraction of the minute that has 
elapsed ; thus, when the second-wheel shall have made a 
revolution while the other wheel is stopped, the mechanism 
will find itself in the position in which it was before the 
hand was stopped, and ready to mark the fractions of the 
subsequent minute. 

At the end of each revolution of the second-wheel, a pin 
which is placed on the other wheel lightly touches a spring, 
and disengages a pinion ; and the spring which presses the 
rack forces this pinion to make a turn, after which it comes 
again to rest on the spring, and the rack finds itself at its 
point of departure. 

To remove all uncertainty in the use of this watch, M. 
Jacob placed a small second-dial by the side of the dial of 
-observation, the hand of which does not stop; the two hands, 
having been set in motion at the same second, should always 

172 the watchmaker's manual. 

continue together ; this addition simply consists in working 
with a third wheel into a pinion of the same number as that 
of the second-wheel, carrying a hand upon the prolongation 
of its axle. 

Description of the Mechanism used for stopping or setting in 
motion the second-hand. 

The cog-wheel, bearing twenty-four teeth, is formed of 
two arcs of twelve teeth, placed above each other. This 
cog-wheel, which turns loosely on a plate-screw, is held 
back by a jumper-spring. The arc which is nearest the 
pillar-plate is free to fall on an arm of a piece which moves 
loosely on a plate-screw, while the upper arc always passes 
without touching it. When the. knob of the watch is 
pressed, a spring, bearing a click at its extremity, falls on 
the tooth of the cog-wheel, and makes it leap forward at the 
instant in which the tooth ceases to retain the arm, the 
following tooth passing above. The piece of which we have 
spoken, being pushed by the spring, touches the wheel 
which carries the second-hand and stops it. When the 
knob is no longer pressed, the spring returns to its first 
position, and the click is ready to force the following tooth 
to leap forward, and, by acting again on the knob, the cog- 
wheel lifts up the piece and frees the hand. 

Apparatus designed to give the duration of any phenomenon, 
expressed in Minutes, Seconds, and Fractions of a Second. 
By M. Henri Robert 

This chronometrical instrument is worthy of attention ; 
it is a small apparatus composed of a circular balance, a 
cylinder-escapement, a wheel, a barrel, and a detent; the 
whole is mounted on a pillar-plate on which two dials are 


engraved; one indicating the minutes and the other the 
seconds and their fractions. 

The spring contained in the barrel is designed to set the 
whole system in motion in a short time; it must be of 
small extent, and its force need not be great, as it is not 
prolonged by a succession of gearings, but acts directly by 
the medium of a single wheel, on the escapement. 

The simplicity of the execution of this mechanism en- 
ables the inventor to offer it at a low price ; this is an essen- 
tial point, as the true merit of M. Eobert consists less in 
having invented a new instrument than in having rendered 
the use of chronometrical apparatus possible for many ob- 
servations for which the instruments already known are 
not used, because their high price renders them inaccessible 
to many. 

The second-apparatus of which we speak is arranged in 
such a manner that when the spring is extended, and the 
hands placed on the hour, it is ready to be set in motion to 
inscribe the duration of an experiment upon the dial ; 
when this experiment is finished the movement is instantly 
suspended to preserve the note of the total duration of 
the observation. 

This arrangement of habitual rest — the action being mo- 
mentary, and dependent on the will of the observer — has 
several advantages ; it dispenses with the necessity of 
remembering the position of the hands at the beginning 
and end of experiments, which it is difficult to do with pre- 
cision when the eye should fix itself on the dial and observe 
the phenomenon at the same time. 

We do not think it is necessary to enter into further de- 
tails with respect to the construction and uses of this chro- 
nometer ; the most essential point is to notice its utility and 
its real merit. We shall only say that it recommends itself 
by its ingenious construction and its moderate price ; and 

174 the watchmaker's manual. 

that the accuracy of its movement is guaranteed by the 
skill and scientific knowledge of the inventor. 

Description of the Second- Watch of M. Robert. 

This watch is designed to mark seconds and fractions of 
a second ; its hand is instantaneously moved and stopped 
by the finger of the observer. The train is so calculated 
that this hand finishes its revolution in two minutes. The 
dial is divided into one hundred-and-twenty parts of a 
second each; the pusher which acts upon the mainspring, 
and causes the train to move or stop at will, penetrates 
into the interior of the case, and rests against the head 
of another spring, a, which is strong enough to raise up 
the pusher, together with a bolt which is forced by a 
small spring to constantly rest upon the head of a spring. 
The rack has an end-piece which is in contact with this 
spring. This rack is propelled by the mainspring, with 
which it communicates by means of a mesh moving be- 
tween two screws, one of which is carried by the rack, and 
the other by the spring. 

Effect. — When the pusher is pushed to the bottom, the 
rack is reversed ; the mainspring is stopped ; the balance 
is checked in its movement by the bolt, which approaches 
it. The hooked end of this bolt comes in contact with 
one of the two pins carried by the balance, and the watch 
is at rest. 

As soon as the finger frees the pusher, the spring lifts 
it up together with the bolt, and the train moves; but 
if the pusher is again pressed slightly, the bolt extri- 
cates itself from the spring, which falls, and stops the 

Thus the pusher exercises a triple function ; when pushed 
to the bottom it impels the mainspring ; when slightly 


pressed, it stops the balance ; and when left to itself, it per- 
mits the piece to go. 

M. Eobert uses a very simple escapement, invented by 
M. Dachemin. This is a cylinder escapement, but the diffi- 
culty of the ordinary wheel is avoided, it being simply a 
flat wheel, whose teeth are cut in an inclined plane. When 
the tooth falls upon the outer surface of the cylinder, it is 
exactly the same as in the common escapement ; but there 
is not, as in the latter, an interior dead-beat ; the cylinder 
acts against the flange of the tooth and causes the train to 
retrograde. This escapement being alternately dead-beat 
and recoiling, the inventor has given it the name of mixed 

Another construction possesses the peculiarity of only 
going while the observer presses a lateral button. In this 
the pusher simply acts as a key, serving to impel the 
spring of the first-mover through the medium of the 
rack. This first-mover is similar to that of the train of a 

The train is arranged in such a manner that the hand 
which is at the centre of the dial completes its revolution 
in one minute, while that of the small hand of the eccen- 
tric dial lasts six minutes. When the lateral button is 
pressed, the mainspring is acted upon by a small bolt, and 
a small spring which serves to raise it. 

When the button is free, the spring of the first-mover 
which keeps it elevated permits another pin to impede 
the movement of the balance by its hooked end, against 
which one of the two pins of the balance props itself; 
but when the button is pressed, the spring acts upon this 
ratch, and removes it from the balance, and the watch goes 
until the finger abandons the button, when it stops instantly. 
Thus this piece goes when the button is pressed by the 
observer, and stops as soon as he frees it. 

176 the watchmaker's manual. 

Detent for Alarm- Watches by M. Robert. 

In this detent, the three pieces of the ordinary detent are 
replaced by a single arm. The instant of the alarm is fixed 
by the fall of the hooked end of this arm into a notch 
made in a disc ; this disc belongs to the alarm- wheel, and 
turns with it upon the hour- wheel, completing its revolu- 
tion in twelve hours. The notch is made in such a manner 
that the striking- work acts at the instant in which the 
hand reaches the figure of the clock. When the spring is 
relaxed, the detent is elevated by the cog-wheel ; but when 
the spring of the alarm is wound up, the cog-wheel no 
longer suspends the detent in air, and the hooked end rests 
on the circumference of the disc until the notch encounters 
it and permits it to fall. 

Chronometrical Indicator and Portable Alarm- Clock. 

The method employed by M. Eobert in his portable 
alarm-clock and indicator, consists in a double second-hand ; 
one of these hands instantly stops when the finger acts on 
a detent arranged for this purpose, — the fractions of the 
seconds being reckoned in fifths upon the dial. This hand 
remains stationary until the observer has noted the time 
it has marked, when, on moving the detent in the contrary 
direction, the hand leaps forward and rejoins the other, 
which has continued to move, and does not quit it until 
the same process is repeated for a new observation. 

By the aid of this instrument, all the observations in 
which the measure of time is required by astronomers, 
engineers, or mechanics, can easily be made with the utmost 
certainty and precision. 

The indicators are small travelling-clocks composed — 


1st, of a movement designed to measure the time ; 2d, of 
a mechanism accessory to this movement, constructed in 
such a manner that a hand stops and marks on a dial the 
second and its fractions expressed in fifths, at the instant 
in which this mechanism acts on a detent, after which this 
hand leaps forward over the arc of the dial which marks 
the duration of its rest ; 3d, of an alarm-train which strikes 
at an hour fixed in advance, and which can be used in the 
morning as an ordinary alarm-clock, and in other cases as 
a warning to notify the observer when engaged in other 
labors that the hour for making the observation has arrived. 

This kind of striking-work may be varied to suit dif- 
ferent tastes and wants ; for persons who rarely have occa- 
sion to use it, it serves as a simple alarm, like those gene- 
rally in use, being composed of a train which is wound up 
whenever the alarm is to strike. 

But this alarm may be made to produce three effects 
for those persons whose habits or business require them 
to rise uniformly at the same hour, as it will strike every 
morning at the same hour while the indicator remains un- 
changed. When one does not wish to be awakened, he 
has only to turn a hand towards the word silence, but if he 
fears that he will not be awakened by the usual alarm, he 
turns the same hand towards the word great alarm, and the 
noise will be so great that it cannot fail to awaken the sound- 
est sleeper. 

4th. Of a striking-train similar to those of common 
mantel-clocks. This arrangement is better adapted to the 
simple alarm than to that producing three effects. In other 
respects, all the combinations used in clockmaking are com- 
patible with the indicator. 

Alarm Mechanism of M. Henri Robert. 

To appreciate the utility of the invention of M. Robert, 


178 the watchmaker's manual. 

we must first review the mechanism commonly used to 
cause the alarm to strike at the proper hour. The case of 
the watch contains a bell and hammer ; this bell is set in a 
rapid reciprocating motion by a train, which is moved by a 
barrel whose spring is wound when the alarm is required to 
strike at a later hour. A detent serves as a stop-work to 
this train, which is made to act by an ingenious machine ; 
a central disc, placed beneath the hour-wheel, raises it up 
by continually rubbing on the end of a pin fastened to this 
wheel. This disk bears a notch on its circumference. The 
instant of the departure of the striking-work is determined 
by the fall of the pin into this notch, when the notch 
presents itself under the pin by the revolution of the hour- 
wheel. The detent then disengages the striking-train, and 
the bell is struck. The moment of departure depends on 
the position of the notch of the disc. This notch is carried 
to the required hour by turning a hand which draws along 
this disc ; and the striking- work acts when the hour-hand 
is above the alarm-hand. 

This mechanism is inconvenient, as the alarm-train con- 
stantly presses the hour-wheel, and impedes the movement, 
whether the alarm is or is not wound, thus requiring a 
greater force for the motive-power ; besides which, the 
instant of the action of the striking- work is uncertain, as the 
radius of the disc which bears the notch is very short, while 
the movement of the pin that falls in it is slow, and the least 
eccentricity of the dial will occasion a great difference in 
the time of striking ; thus the alarm often strikes a quarter 
of an hour too soon or too late. 

The alarms of the common clocks are constructed a little 
differently. The notched disc is fastened to the hour-wheel 
and turns with it ; a ratch-lever, pressed by a spring, rubs 
by its extremity on the circumference of the disc, and this 
extremity, which is beveled, falls into the notch when it 


comes beneath the level, thus extricating the striking- 

M. Kobert has adopted this last mechanism with a modi- 
fication ; but the principal objection still exists, as the spring 
constantly presses the hour-wheel. 

In the construction of M. Robert, the detent has two arms, 
one of which presses the disc, but only when the watch is 
wound ; in the other case a cog-wheel raises the detent so 
that it has no longer any action on the movement ; thus the 
movement of the watch can only be affected by the alarm 
when the barrel of the striking-work is wound. 

Besides, the instant of departure is more precise in this 
alarm than it can be by the ordinary detent, because the 
arm of the lever falls into a notch in the circumference of a 
disc whose diameter can easily be made large enough, and 
which is also concentric to the axis of rotation of the hands; 
the pieces, too, are not so numerous. In ordinary alarms, 
the detent acts by causing the hour-hand to rise and fall ; 
the ratch of this detent is placed in a direction perpendicular 
to the dial, thus increasing the thickness of the watch. 

The detent of M. Robert moves in a plane parallel to the 
dial, and his watch is therefore more convenient to carry, 
less complicated in its mechanism, and surer in its effects. 

It is one of the principles of horology, to prefer a constant 
resistance, though it may be somewhat strong, to a variable 
resistance which can change the duration of the vibrations, 
and to give to the piece an equal movement ; in this respect 
the watch of M. Robert, whose detent only affects the move- 
ment when the alarm-spring is wound, would seem to be 
irregular in its effects, since, when the alarm is wound, the 
movement is under the influence of an unusual pressure. 
But this variable resistance is not objectionable in this case, 
as it is not applied to the escapement, nor even to the last 
motive powers of the train ; it is onlj 7 when the first-mover 


is exposed to this slight accidental resistance that there can 
be any variation in the oscillations of the balance, and this 
mode of construction is certainly preferable to that which 
necessitates a greater motive-power which must finally 
encounter a variable resistance. 

For these reasons, we regard the mode of construction of 
the alarm-watches of M. Eobert as superior to that of 
ordinary alarms, as : 

1st. It diminishes the sum of the resistance, and, conse- 
quently, the force of the motive-power. 

2d. It is a simplification of the pieces beneath the dial. 

3d. It secures greater precision in the action of the strik- 

4th. It diminishes the thickness of the watch. 


I. — The Suspension of the Pendulum. 

One of the most essential things in a pendulum is that 
it shall be suspended in a manner best adapted to its move- 
ment; and the condition is, that its oscillations may be 
made as though around an axis which is the prolongation 
of that of the escapement-piece. 

In general, no precautions are taken to obtain this result, 
and an unskilful apprentice is often intrusted with this part, 
which is, nevertheless, quite delicate and important. To 
arrive at this result, by direct and mechanical means, M. 
Robert prepares the surface which bears the suspension 
upon the turning-lathe, in order to render it parallel to the 
pillar-plates of the movement. The silk passes between two 
turned cylinders whose bases, also turned, rest upon the 
surface parallel to the pillar-plates of the movement, in such 
a manner that — the surfaces of the cylinder being perpendi- 


cular to the pillar-plates — the axis of rotation of the pen- 
dulum is also placed in this manner. This method is much 
less difficult than the one in general use, as the exactness 
depends on the fidelity of the execution of a turned piece, 
instead of the extreme skill which a workman must possess 
to pierce two holes in a straight line on the surface of a 

U. — The Bearing. 

The bearing, or the part of the pendulum which receives 
the action of the fork, is usually a quadrangular rectangled 
prism, which enters into the crossing of the piece called the 
fork — and should enter freely without play into the fork — 
the least imperfection conduces to a defective transmission 
of force. 

The cylindrical bearings of M. Robert do not present this 
difficulty ; they are easily made on the lathe, and, if the fork 
opens parallel, the action is effected with precision. 

Besides, the contact takes place in the plane which divides 
the weight of the pendulum into two equal and symmetrical 
parts ; this condition is necessary in order to prevent the 
oscillations from experiencing any perturbation which might 
affect their duration. 

III. — The Pendulum Ball. 

The two surfaces of a flat pendulum-ball should be planes 
parallel to that of oscillation ; without this condition, the 
pendulum-ball will continually vary by reason of the re- 
sistance which the air opposes, and by careful observation, 
the surfaces of the pendulum-ball may be seen, during an 
oscillation, to form angles differing from the plane of 
oscillation ; this is a cause of irregularity. 

182 the watchmaker's manual. 

To remove this difficulty, M. Eobert replaces the flat 
pendulum-ball by a cylinder or sphere which always pre- 
sents a like surface to the air ; in fact, the cylinder, in its 
section by a plane perpendicular to that of oscillation, by 
offering a larger surface, experiences a little more resistance 
from the air ; yet this consideration, although true in the 
abstract, cannot be of importance in machines of this kind, 
as the most minute observations can hardly detect a dif- 
ference, and in truth, this difference only causes a slight 
absorption of superfluous force in these constructions. 
Besides, the inconvenience of a pendulum-ball which 
trembles in its action is much greater. 

IV.— The Fork. 

In well-executed clocks, a slide is fixed in the fork by 
means of an adjusting-screw; this part thus becomes a com- 
plicated machine which it is difficult to make with precision. 

M. Robert produces the backward and forward movement 
necessary for the escapement-piece, by an arbor-adjustment, 
and an eccentric piece, thus rejecting the adjusting-screw 
with its surroundings. 

The essential quality of the fork is the greatest possible 
lightness, and a perfect equilibrium ; these conditions are 
easily obtained by the eccentric apparatus, while the ad- 
justing-screw does not possess them. 

V. — The Execution of the Escapement. 

The escapement- wheel is made by the artisans who com- 
mence the movement, and when the latter is in the state 
termed rolling, the workman who is to cut the wheel, 
already riveted on its support, in receiving it has no other 
guide to centre it on the wheel-cutting-machine than its 


outer circumference. This operation requires a very precise 
and skilful man ; but, as this cutting is ill-paid, it is neces- 
sarily done quickly, which is often one cause of imperfec- 
tion ; for the wheel, when badly centred, cannot have an 
exact division, even when there are no causes of inequality 
in the tool employed in this work. 

Besides this wheel is taken from a plate of sheet-brass, 
which is never hard enough, and is often of a bad quality ; 
these and other imperfections necessarily produce a bad 
escapement- wheel. 

M. Robert chooses the best brass, which, after reducing 
to a suitable thickness, he tempers by hammering to the 
necessary degree of hardness, but not beyond this, as when 
it is too hard it is often broken roughly, which causes great 

This wheel is pierced at the centre with a hole ; it is then 
crossed and mounted on a tool, made expressly for this 
purpose, on which it is turned and cut ; the outer circum- 
ference being exactly concentric to that of the central 

The verges in ordinary watches, and the anchors in clocks, 
are often injured in a very short time by the friction of the 
wheel. M. Eobert has been convinced by the experiments 
and observations of ten years, that, beside the quality of the 
material of the wheel, several other causes exist which tend 
to the destruction of the escapement, and that one of the 
chief of these arises from the cutting of the wheel. This 
especially happens when the wheel is cut with a new cutting- 
file ; the points of the teeth of this file are covered with 
very fine asperities, extremely hard and easily broken off; 
these asperities soon rub off in the operation of cutting, and 
become incrusted in the teeth of the wheel, thus leaving 
there particles of steel which will soon destroy the escape- 
ment by their friction. This cause of its destruction, which 



is certainly one of the most serious, has never before been 

Various methods have been used by clockmakers, to 
prevent the destruction of the escapement. The best and 
the surest consists, 1st, in passing the teeth of the wheel 
through diluted nitric or sulphuric acid — these acids quickly 
destroy the atoms of steel which the cutting-file has deposited 
on the wheel, and also the particles of oxyd of copper which 
are often found in the material ; — 2d, in then polishing them 
with soft wood and pulverized water-stone, and afterwards 
with charcoal. This is the simplest and surest process. 

The wheel thus finished is mounted on its support which 
is turned smoothly to receive it ; it is not held on this sup- 
port by the riveting made by the hammer in the usual 
manner, but by a bezel-setting made on the lathe, or some- 
times by screws. These methods are not new in themselves, 
as they are practised by the best Parisian clockmakers, but 
the difficulty consisted in introducing them into ordinary 
clock-work without a sensible augmentation of the price, 
and in this M. Eobert has rendered an essential service to 

Clocks running a Month. 

The calibers of the clocks in commerce are still the same 
as those which were used sixty years ago, when the form 
of the teeth, and the imperfections of the work absorbed 
much motive-power; and it has generally been observed 
that there is much superfluous force in these machines, and 
that, in many cases, it is necessary to put in springs which 
are so slight that they roll round, and their bands cling 
together by the falling of the oils, thus rendering the 
drawing very unequal. 

A spring should have a mean force in order to be good ; 


when too strong, it is apt to split or break, and when too 
slight, it has signal inconveniences ; it is therefore necessary 
to arrange and number the train to suit the spring which 
may be applied to it. 

To cause his clocks to run a month, M. Robert places the 
teeth of the barrel of the movement towards the large pillar- 
plate ; the teeth of the two barrels crossing each other, he gains 
thus more than two turns of the spring ; on the other hand, 
he brings the long rod from the centre of the wheel, which 
permits the barrels to be more highly numbered, all other 
things being equal, and finally, he makes the movement- 
wheel somewhat larger and more highly numbered than 
is usual. 

He has thus succeeded in obtaining superior effects with- 
out changing the routine of the artisans, and without sensibly 
increasing the price of the works. 

Alarm- Striking- Work. 

M. Robert adds a small accessory mechanism to the 
striking-clocks, when required, which strikes one blow a 
minute before the hour is struck, thus permitting it to be 
easily counted in the night. This mechanism is very simple 
and inexpensive, and can be easily adapted to most clocks. 


Ordinary clocks, when constructed with the improvements 
which we have described and with the care which they 
always require, both in respect to precision of execution, 
and to the harmony which should exist between the different 
parts of the machine, will doubtless be satisfactory for 
general uses, but we must admit that their movement does 
not yet accord nearly enough with well-made second-clocks 

186 the watchmaker's manual. 

to be able to count on their exactness in observations 
requiring the greatest precision. 

But, as the defects of these clocks are well known, by 
removing the causes which produce them and remedying 
their inconveniences by the resources of art, we shall finally 
obtain machines of great precision. For instance, if we 
replace, 1st, the bases of light, hygrometrical wood, which 
are distorted by the slightest atmospherical changes, by a 
heavy base of marble ; 2d, the light, ill-mounted case of 
wood, alabaster, or copper, by a strong metal frame, fastened 
solidly upon its marble base ; 3d, if we require that the 
dimensions of the escapement shall be proportioned to the 
machine ; an essential condition, as any disproportion con- 
duces to variations and destruction ; 4th, that a suspension 
formed by a silken thread shall be replaced by two steel bars 
whose solidity permits a very heavy pendulum, these bars 
possessing great advantages when well-made ; 5th, that we 
also reject the rod formed of an iron wire, at the extremity 
of which the pendulum-ball is suspended, and the assem- 
blage of pieces which is a ridiculous parody on the compen- 
sation gridiron pendulum ; 6th, that we substitute simple 
constructions, and that the surfaces in contact with the air be 
arranged in the manner best suited to the movement of the 
clock, so that it may not experience any variation ; 7th, that 
the correction of the effects of the temperature shall be pro- 
duced by simple and certain means. We shall thus obtain 
pieces of great precision, which, although they may not 
rival the best second-clocks, will so nearly resemble them 
that no difference can be perceived, except by careful 
astronomical observations. 

Pendulums used in Regulators. 
Besides the pendulum of fir and brass, M. Kobert often 


uses a simple fir ruler, whose lower part, which receives the 
pendulum-ball, is even larger than the pendulum-ball itself, 
and is compressed between the two brass discs which com- 
pose it, and which are called circular followers. 

He also uses, in preference to every other construction, a 
pendulum with two branches, in the execution of which he 
has sought precision in the effects of the compensation and 
the other qualities which should accompany it. The cor- 
rection of the effects of the temperature is produced by a 
single rod of zinc that removes all the difficulties atten- 
dant on the numerous adjustments of the gridiron-pendulum 
while it preserves its advantages. 

Escapement with movable Rollers, by M. Perron. 

The manner in which the escapement- wheel works in this 
construction is very curious. The teeth of this wheel are 
cut at the end in inclined planes, upon which the arms of 
the anchor act successively, in order that the motive-power 
may restore to the pendulum the motion which it loses by 
resistances. To diminish the frictions, M. Perron places a 
movable roller at each end of the anchor which changes the 
frictions. This is the Graham escapement reversed, as this 
celebrated artist also placed inclined planes at the ends of 
the arms of the anchor. The escapement of M. Perron is 
carefully executed in other respects ; to avoid abutments, 
adjusting-screws are arranged at the anchor, which remedy 
this inconvenience. As to the priority of invention, we 
should say, that several years have elapsed since clockmakers 
projected the passing of a part of the inclined planes of the 
anchor upon the teeth of the escapement- wheel. M. Duclos 
did still more, he carried the entire planes on the teeth of 
the wheel. 

M. Grille also took a patent for a dead-beat escapement in 

188 the watchmaker's manual. 

his alarm-clock, in which, he employed a system of wheels 
and inclined planes. 

The escapements of M. Duclos are recoil, but their recoil 
is less than that of M. Perron ; M. Duclos has also used 
dead-beat. Those of M. Gille are dead-beat, but M. Perron's 
are recoil, as he causes the inclined planes to act on the 
movable rollers of the anchor ; while they are not concentric 
to this anchor. 

M. Perron places under the pendulum-ball a horizontal 
bi-metallic band fixed to the suspension rod, so that the 
influences of the temperature, distorting this band, may 
raise or lower the pendulum-ball in such a manner as to 
displace the centre of oscillation on the rod, and to give to 
it an invariable distance from the suspension. 

Clock Indicating the Days of the Month, by M. Gille. 

The clock of M. Gille has a dead-beat escapement, and 
indicates the months, days of the week, and days of the 
month upon distinct dials, whose. hands skip at midnight. 
The most remarkable point in this mechanism is the very 
simple adjustment of the parts which cause the skipping of 
the hands, especially that of the days of the month, which 
skips over the number thirty-one when the month has but 
thirty days ; also skipping the twenty-ninth of February 
except in the bissextile years. 

Yarious methods were before employed in order to obtain 
this result, but the mechanism was very complicated, having 
generally a wheel with 366 teeth, which, made an annual 
revolution, one of these teeth being useless in the common 
years. This apparatus required much room, was adjusted 
with difficulty, and was very costly. That of M. Gille can 
be lodged in a very small space, as it has but three pieces 
more than an ordinary clock indicating the days of the 


month, while the highest numbered wheel has but thirty- 
one teeth. 

The large dial of the clock is pierced at the centre to 
permit the passage of the axles of the hour and minute-hands, 
and is also pierced at three other points of its surface for the 
passage of axles to the centres of three small dials for the 
days of the week, days of the month, and names of the twelve 
months. Each of these three dials is furnished with its indi- 
cative hand, the skipping of which is produced by the gene- 
ral mechanism of the piece. 

First, the hand of the days of the week is mounted on an 
axle which carries a star-wheel with seven points, and the 
detent which causes it to turn one notch at midnight also 
causes the hand to pass over one-seventh of the circumfer- 
ence, thus passing from one day to the next. 

The hand of the second dial — that of the days of the 
month — is mounted on an axle which carries a wheel of 
thirty-one teeth ; this is the wheel upon which the mechan- 
ism of M. Gille acts in order to render one, two, or even 
three teeth of this same wheel useless, when the hand is to 
skip as many numbers at a time. For this purpose, the axle 
of the days of the month carries a sort of rack armed with 
four unequal pins. The limb of the month-wheel is not 
toothed, but carries pins implanted like those of the striking- 
hammer, except that these pins are of different lengths and 
are twelve in number. A pin is caught at the end of each 
month, making the month-wheel skip one notch ; the result 
is, that according as the month has 30 or 31 days, such or 
such a pin of the rack acts, thus determining the skip. 
The month of February is furnished with a pin which 
causes the hand to skip three days at once, the short pins 
are for the months of 31 days. 

As regards the bissextile years, there is a small wheel 
which revolves once in four years, and which carries a 


larger tooth, filed in a curve, in order to elevate the wheel 
on the 28th of February, so that the pin of that date, which 
is the longest, and which is always raised up by that of the 
rack, can pass, thus indicating 29 for the following day. 

This mechanism is simple, ingenious, and easy of execu- 
tion ; its functions are guaranteed, and as it requires little 
space it will be generally adopted instead of the numerous 
pieces and the annual wheel formerly used. As clocks are 
now regulated by the mean time, and as equations serving 
to give the true time are rarely needed, the annual wheels 
will seldom be used in horology, and a mechanism of this 
kind, which dispenses with their use, will be very con- 

Compensation-pendulum of M. Duchemm. 

The variations in length which a pendulum experiences 
by the influence of the changes of temperature, cause alter- 
nate delays and advances in clocks; these effects, which 
change the uniformity of the movements of clocks, were 
long considered as an irremediable evil ; and the idea was 
ingenious that first suggested the use of this same dilata- 
tion to counteract these effects by a suitable adjustment of 
bands of different metals. When the dilatation of metals in 
the same variation of atmosphere was perceived to be dif- 
ferent, experiments were made to render this property avail- 
able in securing a constant length to the pendulum. For 
this purpose, vertical rods of two metals were used, joined 
together by horizontal cross-bars, in the form of a gridiron, 
in such a manner as to raise the pendulum by the elon- 
gation which one of these metals experienced, precisely as 
far as the elongation of the other lowered it. This required 
that the total length of the bars of the first metal, supposed 
to be placed at the ends, when compared with the length of 


those of the second metal, should be in exactly the same 
proportion as the respective dilatations of these two metals. 
The two symmetrical and parallel rods of the same metal 
should be counted as but one in this calculation ; by this 
the pendulum seems insensible to the variations of tem- 
perature, and its centre of oscillation remains at the same 
distance from the suspension, whether the weather be warm 
or cold. 

But although this rule is exact in theory, it is difficult of 
application, as numerous experiments are necessary to obtain 
the exact proportion required, and each time the defects are 
only evinced by long experiments, which consist in sub- 
mitting the pendulum to alternate proofs of extreme tem- 
peratures, then taking it apart to file the rods and unite 
them again in different proportions; this is difficult and 
expensive, and renders the compensation-pendulum costly 
and difficult of execution. 

Now, the lengths of the bars of the gridiron are doubt- 
less determined in advance by the law of the linear dilata- 
tion of each metal, and these bars may easily be cut in 
lengths according with this rule ; they should be made of 
zinc or brass, and steel, and be cut and joined together in 
conformity with the lengths required by the rule. This 
rule is, that the bars of steel shall be to those of brass as 5 
is to 3, and to those of zinc as 6 to 17. 

To fulfil these conditions, the pendulums of brass and 
steel should be of nine bars, but those of zinc and steel 
require but three or five bars on account of the great 
dilatability of zinc ; the last system, therefore, is now gene- 
rally preferred. 

The pendulum thus formed will not be an exact com- 
pensator, for reasons which we shall presently state, but it 
will so nearly possess this advantage that when we consider 
that the clocks in our apartments are not subjected to great 

192 the watchmaker's manual. 

changes of temperature we may be satisfied with it. We 
recommend this method because it does not require addi- 
tional expense, and possesses advantages equal at least to 
those of the watch-compensations with bi-metallic arcs, in- 
vented by Breguet. 

But when the compensation-pendulums of astronomical 
regulators, and other pieces which are valuable on account 
of the uniformity of their movements, are to be made, we 
should not rely on the simple rule which has just been pre- 
scribed, for the following reasons : Metals are never homo- 
geneous ; even the manner in which they are worked, 
according as they are cast, hammered, or filed, changes the 
quantity of their dilatation ; and as the surest method of 
measuring this effect is that of making a pendulum, causing 
it to vibrate, and reckoning its oscillations in different tem- 
peratures, it is evident that a precise compensation-pendulum 
can only be obtained by submitting it to successive essays, 
correcting it, etc. 

But M. Duchemin has succeeded in avoiding these diffi- 
culties by a method at once sure and simple. His pendulum 
is of precisely the same form as an ordinary gridiron-pendu- 
lum of five bars of zinc and steel. He makes these bars 
of suitable lengths in conformity with the known rule ; but 
he has discovered a method of varying the bars of zinc in 
their place at will, in order to find the precise compensation 
by experiments made upon the movement of the pendulum 
without taking it apart. 

It is difficult to explain clearly the adjustment of the bars 
without figures, we will but say that the rods of zinc are 
only connected to those of steel by cross-bars which support 
adj usting screws ; and that these screws can be made to act 
upon different points of the rods, and, consequently, can 
lengthen or shorten them, according as the compensation 
may be found to be too great or too small. The pendulum 


remains mounted in its place ; it is only stopped for a 
moment to move the screw and is then immediately set in 
motion without changing the general movement of the 
piece, the compensation alone being varied. This process 
is so easily executed that it is unnecessary to apply to a 
clockmaker to effect the change. 

Compensation-pendulum of M. Jacob. 

M. Jacob, a Parisian clockmaker, has also endeavored to 
•find a method of substituting for the gridiron pendulum 
another performing the same condition — that of rendering 
the apparatus insensible to the variations of temperature. 
He avails himself of the unequal expansibility of the metals 
by heat, but the arrangement of his apparatus is new, and 
the joint responsibility which he has established between 
the zinc and the steel seems to fulfil perfectly the design of 
the author. This adjustment is made as follows: 

The suspension-rod is of steel, cut in the form of an oval 
cylinder, and of a length suited to the duration required 
for its oscillations. At the lower part of its length, it is 
encircled by a sort of zinc cover or case formed of two 
tubes of this metal, which are joined on their edges by 
several adjusting-screws in order to fix the apparatus solidly 
bjr small cross-bars. The system of the steel rod and its 
zinc cover are free and independent of each other ; but to 
hold back this zinc cover and prevent it from sliding on 
the suspension rod, the. lower end of the steel rod is cut with 
a thread and furnished with a screw-nut upon which this 
cover rests ; this screw-nut serves to obtain mean time in 
the usual manner. 

The top of the cover is in the form of a screwed cylinder 
and carries a screw-nut, which, being underneath a ferrule, 
serves as its support ; this ferrule serves as a point of sup- 



port to two steel rods which, by their lower end, are fixed 
to the pendulum-ball and support it ; it being understood, 1st, 
That the pendulum-ball is entirely independent of the steel 
rod, and that its zinc cover only serves it as a support ; 2d, 
That the length of the zinc cover is calculated, according to 
the law of dilatation, to produce a greater effect than is 
needed, so that to regulate it, it will be necessary to shorten 
it by means of the screw-nut. His ingenious apparatus 
produces the following effect : 

Let us suppose that, after having adapted the pendulum 
to a good clock, and regulated the length to a constant 
temperature, we wish to adjust the compensation. 

We raise the temperature by the usual methods and find, 
for instance, that the clock gains more or loses less time than 
before ; we therefore conclude that the heat lengthens the 
steel suspension-rod, which should produce a delay, but that 
the screw-nut serving as a support to the pendulum-ball on 
the zinc cover is also lengthened, and that the pendulum- 
ball has been elevated in the same proportion ; so that it 
has raised more by the second effect than lowered by the 
first. The pendulum, therefore, has really been shortened, 
and the centre of oscillation brought nearer the suspen- 
sion ; the zinc part is thus too long compared with the 

To shorten this, we turn the screw-nut, which is beneath 
the ferrule of support of the pendulum-ball, in the direction 
proper to lower the latter ; this produces two effects, 1st, 
that of shortening the zinc tube which produced too great 
a compensation ; 2d, that of lowering the centre of oscil- 
lation, which would retard the clock ; but as this last effect 
would tend to derange the general movement, we wind up 
the centre of oscillation again by turning the screw-nut of 
the end of the suspension-rod. As the threads of the 
screws are the same, or very nearly so, the desired quanti- 


ties may easily be marked on both by means of an index 
and equal divisions on each screw-nut, so that the compen- 
sation alone may be influenced. 

We can thus adjust this compensation -pendulum, not 
only without taking the clock or pendulum apart, but almost 
without stopping it, or at least by stopping it for a single 
moment, so that we can moderate the compensation without 
trouble, expense, or time ; and nothing can be easier than to 
manage this apparatus and to obtain the highest degree of 
exactness by repeated essays, with the same facility as for a 
simple pendulum. 

One of the results which the clockmaker should guard 
against in the construction of compensation-pendulums, and 
the one which is most injurious to gridiron-pendulums, is the 
bending and sinking caused by the heavy weight of the 
pendulum-ball on the adjustment-rods which support it; 
this weight is perpetual, and it therefore follows that the 
compensation cannot be perfect. When the pendulum is 
first constructed it is impossible to regulate it ; the pieces 
must first produce their effect under the influence of the 
weight which draws them down. At the end of a certain 
time they are tried, and the regulation of the dimensions 
of the bars of the two metals is attempted ; repeated experi- 
ments are necessary for this, and at the end of a long time, 
a year or more, a correct pendulum will finally be obtained. 
The weight of the pendulum still acts, but the band of the 
metals has learned to resist it. 

We shall not attempt here to compare the compensative- 
pendulums of MM. Duchemin and Jacob ; these two mechan- 
isms, although constructed on the same principles, are of 
different natures ; one only attempting to obtain a sure and 
easy method for the regulation of the gridiron-pendulum, 
while the other has invented a new pendulum which we 
will call the cover-pendulum, to distinguish it from the first ; 

196 the watchmaker's manual. 

both inventions are worthy of praise, and either can be 
chosen with the certainty of making a good choice. 

M. Jacob is also known as the inventor of an indicator 
which has been well received ; and which is declared, 
in a year's trial, not to have lost or gained more than 
half a minute per month. The pendulum-rod is of wood, 
properly chosen and prepared", so that neither the length 
nor the form may be changed by the variations of tem- 
perature, or the humidity of the atmosphere. We know, 
indeed, that the temperature does not lengthen the wood, 
and that the torsion of the rod, by the influence of the 
humidity, may be avoided by the application of a suitable 

Sphere- Clock, hy MM. Soyez and Inge. 

This apparatus is formed of a terrestrial sphere of metal 
or any other material, hollowed out, and containing a clock- 
movement in its interior which causes the globe to turn on 
its axis ; the zones being of an equal weight in the whole 
length, in order that the rotary movement of the globe may 
be also equal. 

Its axis, fixed by its ends on the half of the meridian, 
which is left as a point of support, is held on the horizon, 
the point where the half of the meridian reaches, to obtain 

Upon the middle of the axis, an ordinary horarjr move- 
ment is also fixed, either with or without striking work, but 
whose minute-wheels are less ; the globe making its revo- 
lution in twelve or even in twenty -four hours, if required. 

At the top of the movement, and fixed by this means to 
the middle of the globe, is carried the pinion which belongs 
to the axle of the large hand in the ordinary movements 
at the top of the pillar-plates, so as to reach the extremity 


of the radius of the sphere, and thus to obtain a more power- 
ful lever. 

A wheel, whose cogs are twelve or twenty -four times more 
numerous than those of the pinion of the large hand (sup- 
posing a movement for each hand), is fixed in the interior 
of the globe, by three levers, upon three interior points of 
its circumference. This wheel works into the pinion of 
the large hand, and being attached to the globe, thus com- 
municates the action to it by this point of contact with the 

The globe is movable on three points, namely : 

1st, The two poles on the axle near the horizon and 
meridian circles. 

2d, Upon the centre of the great wheel, the axle of which 
is fixed to the end of the movement. 

The globe thus makes its revolution in the twelve hours 
inscribed in the great circle of the equator, and in that of 
the horizon and the meridian. 

The hours and minutes are marked on the equator ; by 
this method, each meridian and each point of the sphere 
passes successively and regularly under each hour and each 
minute ; thus indicating the hour at every part of the world 
at a single glance. 

It should also be remarked that the hours should be traced 
from the right to the left, in order to give the true position 
of the earth. 

Universal Clock, indicating the Actual Time beneath every 
Meridian, by M. Duclos, of Paris. 

This clock shows the hour of each meridian, and the 
general effect of the division of the day for the different 

The equator is drawn upon a circular and immovable 

198 the watchmaker's manual. 

band, this is divided into three hundred and sixty de- 
grees by the intersection of meridians, which are numbered 
in tens, choosing any given place for the point of depar- 
ture. The hundred and eighty degrees of west longitude 
are marked from right to left, while the hundred and eighty 
degrees of horizontal longitude are marked from left to right. 

The most remarkable places of the globe are indicated 
above this division, according to their respective location 
(in longitude alone) ; these may be more or less numerous, 
according to the diameter given to this equatorial band. 

A second circle, parallel to this fixed band, is placed above 
and somewhat in the interior; this bears twenty -four princi- 
pal divisions, in which the twelve hours of the day, and the 
twelve hours of the night are marked. The divisions of the 
minutes are placed beneath, in such a manner that the 
lower border of this circle corresponds with the upper 
border of the equatorial band. 

This hour-circle revolves horizontally once in twenty- 
four hours, moving from east to west, according to the 
apparent diurnal revolution of the sun around the earth ; 
consequently each hour presents itself successively beneath 
each meridian, and all the meridians correspond continually 
to the hour which they should indicate as soon as this corre- 
spondence has been established by setting the clock at the 
hour of the first meridian, at which point a principal indi- 
cator is fixed. 

The movement is communicated to the hour-circle, and to 
every part of the circle which invests it, without any apparent 
train in the interior of the model, which may be transparent; 
no piece of clock-work can be perceived. 

All of this movable part is fixed through the centre of the 
hour-circle on a perpendicular axle ; this axle is prolonged 
and passes through an obelisk which is placed between 
figures or columns. 


A movement of clock-work is placed horizontally in the 
pedestal of the clock; one of the motive-powers of this 
movement revolves once in twenty -four hours, and the long 
arbor which it carries occupies the centre of the pedestal. 
This long arbor, which passes through the upper part of the 
pedestal, receives a socket inserted with a strong friction, on 
which the lower extremity of the axle is mounted, the other 
extremity being fixed to the centre of the hour-circle. 

The movement of clockwork, whose caliber is arbitrary, 
provided that one of the motive-powers revolves once in 
twenty-four hours, and that its regulator is a balance, needs 
not to be described here any more than the escapement, 
which should be chosen from those best known. A remon- 
toir is adjusted beneath the pedestal, which can be turned 
without a key. The whole piece can be moved without 
stopping it. The inventor proposes to make this clock in 
different sizes, with striking-work, and the days of the 
month ; he also intends to apply the mechanism that has 
just been described, to indicate the actual time under every 
meridian without a dial, by the correspondence of two con- 
centric circles ; one of which will remain stationary while 
the other will revolve in twenty-four hours. 

Alloy for Horology. 

Mr. Bennet, an English clockmaker, has discovered an 
alloy which is well suited to the manufacture of the sockets 
of pivots of ordinary watches. 

He has succeeded best with the following composition : — ■ 

Pure gold, Parts, 31 ^ 

Pure silver, " 19 f , Q0 

Copper, " 39 ( 

Palladium, " 11 ) 

Palladium readily unites with the other metals; the 

200 the watchmaker's manual. 

alloy liquefies at a lower temperature than is required to 
melt the gold separately, and, after cooling, is harder than 
hammered iron. It is of a reddish-brown color. It is as 
fine grained as steel, and is worked almost as easily as brass, 
but its friction is much slighter on ordinary pivots. Its 
most valuable property is this ; that the oil it absorbs is not 
decomposed, but remains pure, in a fluid state. It has still 
greater advantages over sockets of fine stone, as it is not 
apt to break, is susceptible of a perfect polish, and is much 
less costly. 

Method of Measuring Mean Temperatures. 

M. Jurgensen, a celebrated clockmaker of Copenhagen, 
who is known by a treatise on detached escapements, and 
by the excellence of his chronometers, has conceived the 
idea of employing these chronometers in the determination 
of the mean temperature of twenty -four hours. We know 
that to preserve a watch from the variations of temperature, 
we must adjust to the balance a band in the form of an arc 
of a circle, composed of two metals, whose unequal dilata- 
tion opens or closes the curvature, in such a manner as to 
retard or accelerate the movement. 

Now, in order to apply it to the measure of mean tem- 
peratures, the concavity of the arc must be placed inside ; 
this doubles the variation caused by the temperature. M. 
Jurgensen has added besides a second arc to render the effect 
still more sensible, and thus obtains a variation of thirty- 
one and a half seconds for a degree of temperature. 

It is evident, therefore, that if the instrument is com- 
pared with a regular chronometer, one will know how far 
the temperature has been above or beneath a given tem- 

The movement of this instrument, however, must first be 
regulated to a fixed temperature, as that of zero for instance. 


Method of Hermetically Covering Mantel- Clocks. 

Every one has probably remarked the dust that pene- 
trates into the interior of mantel-clocks, despite the balloons 
and bell-glasses with which they are generally covered, and 
that the quantity is greater in proportion to the carpets 
with which the rooms are furnished, — the inexhaustible 
receptacles of a fine and impalpable dust which is not the 
less real because not perceptible to our senses. 

However firmly closed our clocks may be ; however well 
made may be their glass and crystal coverings, they will 
not prevent the introduction of this dust, which tends to 
penetrate them still more when the air of their interior 
produces an equilibrium with that of the rooms. 

We may easily j udge of the effects which the introduc- 
tion of this dust will produce in time on the delicate trains 
and movements of costly clocks, when we see the thick 
coating of dust which is deposited every day on the furni- 
ture of carpeted rooms, and those wherein numerous assem 
blies collect. To remedy this, M. Robert covers the edge 
or the lower part of the bell-glasses or balloons, not with a 
thick velvet or a double chenille, but with an elastic 
cushion, which forcibly enters into the conical part of the 
pedestal, so as to press strongly against the pedestal in its 
whole circumference, in order to prevent the air from pass- 
ing between the two parts, at least unless impelled by a 
great pressure. 

The pedestal is hollow, or in the form of a box, com- 
posed of a circumference, a bottom, and a cover; it is 
divided into two parts by a diaphragm or pocket of gummed 

The bottom and the cover are both pierced with an aper- 
ture ; that of the bottom establishes a communication be- 



202 the watchmaker's manual. 

tween the exterior air and the part of the pedestal beneath 
the diaphragm, while that of the cover establishes it be- 
tween the air of the bell-glass and that of the upper part 
of the pedestal. 

In consequence of this arrangement, which is as ingeni- 
ous as simple, an equilibrium is produced between the out- 
side air and that of the bell-glasses, according to the varia- 
tions of temperature in the rooms, without any penetration 
of dust ; since, when there is a dilatation of the air con- 
tained in the interior, the taffeta diaphragm yields and de- 
scends into the lower part of the pedestal ; while if the air 
is condensed, it rises until the equilibrium is again esta- 

Inconvenience of the oak wood used in the construction of the 
Cases of Clocks and Astronomical Instruments. 

A letter to the editor notices an important observation 
made by an astronomer relative to the effect produced by oak 
wood on the metals which come in contact with, or near it. 
The pieces of a costly clock were twice unaccountably covered 
with rust, though the other instruments in the same observa- 
tory were not thus affected. The clock was fastened between 
two pieces of wood, the front being mahogany and the back 
oak ; these pieces were joined together by bars of copper 
screwed into their lower extremities. Suspecting that the 
evil sprang from the influence of the oak wood, these rods 
were taken out, when it was perceived that while that part 
of their length which had passed into the mahogany was 
bright, that which had penetrated the oak was covered 
with an oxyd, or salt of copper. A chemist, who was 
called to examine this case, attributed the whole evil to the 
influence of the oak wood. Small holes having been 
pierced into the piece of wood by means of a drill, some 


of the particles taken therefrom were heated in water 
over the flame of a taper, and this water instantly red- 
dened litmus paper. It was needless, in fact, to have re- 
course to this process, as pieces of litmus paper, intro- 
duced into the holes made into the wood, were deeply 
reddened in a few seconds, proving that there was an ex- 
tremely volatile acid in the oak wood ; the same experi- 
ments failed to discover any trace of acid in the mahogany. 
The chemist was of the opinion that the influence of the 
oak could only be remedied by varnishing or veneering it. 
Other examples of the same effect on astronomical instru- 
ments have been cited. Nor will this action of oak on 
metals seem strange when we reflect that the bark of this 
tree contains tannic acid, and that it also bears the ex- 
crescences which, in certain species, take the name of galls 
and produce acid. 



We do not intend to give here a list or description of 
the numerous tools employed in clockmaking, as a large 
volume would hardly suffice for this purpose, but shall limit 
ourselves to the description of some ingenious specialties 
of utility. 


1st. — Method of Straightening the Pinions. 

When clockmakers have rounded and filed a pinion 
thin enough, they blue and temper it. This usually warps 
the rod of the pinion, which becomes crooked on the two 
points which served to turn it, and the workman is then 
obliged to straighten it with the file. If, on the other 
hand, the difference is small and the size of the rod permits, 
he straightens the rod by means of an edged hammer on a 
smooth hand-anvil by striking in the hollow in order to 
elongate this part, or, which is preferable, he places a very 
smooth file in the vise in such a manner that its cut side 
may be placed above. He then rests the hollow side of 
the rod on this edge, and strikes the opposite part with the 
head of a smooth hammer ; the cuts of the file, being very 
fine and close, perform the functions of small chisels or 
edged hammers, and the straightening is made with greater 
speed and regularity. 


This being done, the workman turns and rounds the 
points, and turns the rod and polishes it in the same manner 
as the leaves of the pinion. 

Pinions may be procured in the shops ready made and 
polished, and of different lengths and numbers, which can 
easily be adjusted to the watches most in use ; but these 
pinions are seldom round, and a careful workman should 
examine them in this respect before using them, in order to 
rectify the errors or to assure himself that none exist. The 
instrument of which we shall speak will be useful in both 
cases. Figures 1 and 2 (PL VI.) represent it ; in profile in 
Fig. 1, and in front in Fig. 2. The same letters indicate 
the same pieces in both figures. 

This instrument is simply a support of a finishing-lathe. 
The rod, A, enters into the rest of the lathe, which we have 
not thought necessary to engrave, and is fixed at the proper 
height by the screw of the holder. The plate, B, which is 
placed at right angles and riveted on the upper part of the 
rod, A, is brought near the turning-tools of the lathe ; this 
is pierced with several holes, E, cut with the same thread 
of the screw, to receive the screw, C, which is introduced at 
the proper point by means of the thumb and forefinger. 
This screw is of steel, pierced in its axle, into which is ad- 
justed a small piece of brass resembling the head of a pin. 
The rest of the machine is of brass. The screw is placed 
in one of the holes, E, which is the most convenient for the 

The tool is represented of its natural size, and is used in 
the following manner: The workman, after having fixed 
a screw-roller on one of the rods of the pinion, places it 
between the two turning-tools of the lathe, and turns it 
slowly with a horse-hair drill-bow which he holds in his 
hand, gradually advancing the screw until its point renders 
all the leaves of the pinion even. If the rod is crooked, 

206 the watchmaker's manual. 

he straightens it again by the method which we have in- 

Clockmakers had previously used a similar method, but 
one less certain. They took a brass point, a large pin for 
instance, rested it on the support of the lathe, and brought 
it near the leaves of the pinion ; but, having no means of 
fixing the distance in an invariable manner, the friction was 
not sensible enough to work accurately. 

2d. — Lathe for Rounding Pivots. 

A good lathe for rounding pivots is a valuable tool, 
especially in the present state of clockmaking. The holes 
made in the two puppets to receive the turning-tools should 
be exactly opposite each other, and in a straight line through 
their whole extent, so that if a turning- tool were passed 
from one puppet into the other, it would glide there with 
as much ease as if one of the holes only formed the con- 
tinuation of the same cylinder. It is therefore necessary 
that the part of the turning- tool of the lathe which • receives 
the extremity of the axle opposite to that which bears the 
pivot to be worked should be exactly in a straight line with 
the notch made in the extremity of the other turning-tool, 
parallel to the axle of this turning-tool ; for when this does 
not take place, the pivot is cut at the bottom, or is conical, 
or breaks when it is rounded. 

M. Vallet has remedied these inconveniences by the con- 
struction which we are about to describe. Figure 3 (PI. VI.) 
represents this instrument in front, fixed into the vise by the 
foot, A, The two puppets, B, C, do not differ from the 
puppets of ordinary pivot-lathes ; the} 7 carry the two turn- 
ing- tools % D, E, which are fixed in the proper position by 
the screws, F, Gr, which rest upon the cushions, H, H, as in 
ordinary lathes. Each puppet carries a shaft, I, K, whose 


use we shall presently show. Each pike of the lathe carries 
a kind of wheel, L, J, divided into twelve large teeth, and 
the two shafts, I, K, enter exactly into the empty space left 
by two teeth, in order to fasten the turning-tooi perfectly, 
so that it cannot turn, while the upper screw, F or Gr, hinders 
it from advancing or retreating. 

The turning-tool, D, is terminated on the inner side of the 
lathe, by a steel turning-gauge, M, which is fixed by a strong 
screw to the end of the turning- tool. This plate, M, is 
pierced with a hole towards the extremity of one of its 
diameters. This hole, which is perfectly cylindrical and 
parallel to the axle, receives a pike, P, which serves first to 
mark the corresponding holes in the turning-gauge, K, of 
which we shall presently speak, and then to support one of 
the extremities of the axle, the pivot which is to be rounded 
being placed at the other extremity. 

The pike, P, enters cylindrically and closely into the hole 
of the turning-gauge, M ; its outer part is conical and 
pointed. It is tempered blue and then adjusted. When it 
has served to mark on the turning-gauge, K, the twelve 
holes of which we shall presently speak, its point is slightly 
filed, and a shallow hole is pierced in its centre, which after- 
wards serves to receive the extremity of the axle of the piece 
which bears at its other extremity the pivot that is to be 

The other turning-tool, E, carries between the two puppets 
two pieces, N, O, whose construction should be understood. 
The part of the turning-tool concealed by the pieces, N, O, 
is turned cylindrically as a pivot smaller than the turning- 
tool, but large enough to receive a screwed hole and a 
strong screw. The turning-gauge, 0, entirely covers the 
species of pivot of which we have just spoken. The 
turning-gauge, N, has one hole of the size of the screw 
which consolidates the whole ; the head of this screw is 

208 the watchmaker's manual. 

sunk into the turning-gauge, as it might sometimes be 
injurious if it should project. 

The turning-gauge, N, has, on its circumference, twelve 
notches, varying in size and depth according to the size of 
the pivots to be rounded. These notches should be carefully 
made ; they should be exactly parallel to the axle of the 
turning- tool, and perfectly semi -circular. 

To make these notches in such a manner that they will 
be exactly opposite the pike, P, it must be remembered that 
this pike is at first pointed and very sharp. The turning- tool, 
D, is brought in contact with the pike, I, by a tooth of the 
wheel J ; the pike, E, is likewise connected with the pike, K, 
by a tooth of the wheel, L ; the head of the pike, D, whose 
adjusting-screw, F, is not fastened, is struck, and a point is 
marked on the turning-gauge, N". The place of the wheel, 
L, is changed, and, consequently, the turning-tool, E, turns 
one-twelfth ; another point is then marked, and so on until 
the whole twelve points have been marked. A hole, 
parallel to the axle, is pierced at each point, by means of 
drills proportioned to the size of the pivots to be rounded. 
These holes being made, the turning-gauge, N, is filed in facets, 
in such a manner as to remove half the cylinder which this 
hole has formed, making it so that the plane of this facet 
may be perpendicular to the vertical plane which shall pass 
through the axle of the turning-tool, and that the notch 
which has formed the uncovered hole shall divide the facet 
into two equal parts. Much care is necessary to obtain a per- 
fect execution, but this is indispensable to a successful result. 

The turning-gauge, 0, is filed in facets parallel to the 
axle of the turning-tool ; it carries twelve facets whose 
distance from this axle is proportioned to the size of the 
pivot before which they present themselves. The middle 
of each facet should correspond to the middle of the notch 
before which it is placed. These facets are designed to 


support the pivot-file or burnisher, which should be rested 
upon them in such a manner that the file may be parallel 
to the axle when the pivot is finished, so that it may be 
perfectly cylindrical. 

3d. — The Pivot- Compass. 

Berthoud demonstrated the importance of arranging the 
size of the pivots in watches in such a manner that the 
wheels which have the most rapid movement may have 
the finest pivots. He also proposed an instrument for 
attaining this end, but it was not satisfactory, and was there- 
fore abandoned. 

M. Vallet, being convinced of the importance of an 
instrument of this nature, has perfectly succeeded in the 
following invention. 

Figure 4, PI. VI., represents this instrument in elevation. 
Figure 5 gives a bird's-eye view of it, and Figure 6 shows 
the mechanism. The same letters indicate the same object 
in the three figures. 

The machine resembles a watch-case, A, A, supported by 
three feet, B, B, B, in order to raise it to a convenient 
height. The mechanism is concealed by a dial, C, divided 
into 360 equal parts, numbered in tens, which a slender 
hand, D, passes over, to indicate the opening of the compass. 
The whole is covered by a convex-glass, E, resembling a 
watch glass. Upon the side, we perceive two arcs of a circle 
F, R; R, G-, which are the feet forming the compass-piece, in 
polished steel, and which only separate when some body is 
passed between them. This instrument is so susceptible that 
a hair will suffice to turn aside one of the feet, and the hand 
will instantly indicate the diameter of the hair on the dial. 

The instrument is constructed in such a manner that the 
hand will pass over the whole circumference of the dial, 


when the movable foot is turned aside three lines ; a line 
is therefore divided into 120 equal parts, with mathematical 

Figure 6 shows the mechanism as disclosed by the removal 
of the dial. One of the feet, Gr, of the compass is fixed in 
the case by a screw, H, and two chicks. The other foot, F, 
is movable ; it carries within the case an arm of a lever, K, 
whose centre of motion is at the point, I. This arm of a 
lever is riveted to a vertical axle, which moves on two 
pivots which roll in the pillar-plate, and in the bridge, S. 
This same axle carries a rack, L, whose teeth, 1ST, work into the 
leaves of a pinion, M, of fourteen teeth, the pivots of which 
are also carried by the pillar-plate and by a bridge. A 
spiral-spring, O, strong enough to bring back this slender 
mechanism to its place, is fixed by one end to a ferrule 
carried by the pinion, M, and enters by the other end into 
the screw-ring, P. The whole is arranged in such a manner 
that when the two feet of the compass touch each other, the 
hand, D, rests on the number 360. 

To find the size of the pivot which is to be made, it is 
passed between the two feet at the point R, and is re- 
duced until the hand indicates the point at which it should 
stop. In order to give greater facility for opening the 
compass when the pivot is presented, the end of the fixed 
foot is imperceptibly turned off, so that the thickness of 
the movable foot slightly exceeds that of the fixed one. 
By this means the compass opens without any resistance 
when the pivot is rested against the movable foot. 

4th. — Compass for Turning Cylindrical Rods. 

In the construction of the compass for rounding pivots, 
M. Vallet experienced much difficulty in turning cylindri- 
cal rods by the aid of the calipers which were then used. 


The invention of the pivot-compass, which we have just 
described, suggested the idea to him of applying it to the 
turning of rods cylindrically. 

Figures 7 and 8, PI. VI., will suffice to show this useful 
instrument. Figure 7 shows the tool in front ; a plate, A, 
A, of well-hammered brass, whose form is indicated in the 
figure, shows in the upper part a rim divided into equal 
parts, which are marked in fives by figures. This plate is 
first turned round, and is then detached to give it the form 
of the figure. A hand, a, is placed at the centre of the 
tool, which marks the degrees of opening of the compass 
on the rim, b. This hand is fixed on the extremity of 
the pivot of a steel rod, which is in a frame on the back of 
the tool, between the plate, A, which constitutes it, and a 
small bridge fastened on this plate by a screw and two 
chicks. A ferrule is adjusted with a strong friction on the 
prolongation of the upper pivot; this receives the inner 
end of the small spiral-spring, d ; the hand, a, is also placed 
above with a strong friction. 

Two feet of a pair of compasses, constructed like those 
of the pivot-compass, are represented in Figure 8 on a 
double scale ; the foot, G, is exactly similar to that of the 
compass (Fig. 6), and is fixed in the same manner. The 
other foot, F, differs slightly from that of the pivot com- 
pass ; it does not carry any rack, but its second arm of a 
lever, H, carries the screw-ring of the spiral -spring, or, to 
speak more correctly, is pierced parallel to the plate, so as 
to perform the functions of a screw-ring. The second foot 
of this tool is carried, like that of the pivot-compass, by a 
small axle and two pivots, one of which rolls in the plate, 
and the other in the bridge, D. 

The mechanism of this instrument may be easily under- 
stood. When the point, R, is in contact with a rod placed 
on the lathe, the two feet of the tool separate, and the 

212 the watchmakee's manual. 

spiral-spring is carried to the left ; this causes the hand to 
move on the rim, and marks the degree of opening. By 
conducting the tool along the length of the rod, the exact 
difference may be perceived, and the inequalities corrected. 
At the top of the plate a knob, E, is riveted, which serves 
to hold it by the fingers when it is worked. 


The workmen who were occupied in the construction of 
the cylinder-escapement had long demanded tools which 
would assure to them a perfect regularity in the manufac- 
ture of the teeth of the cylinder- wheel. They had already 
succeeded in perfecting the cylinders, but they had not 
taken the same precaution for the wheel. 

M. Yallet perceived, — 1st, that the inclined plane of every 
tooth should be perfectly equal in each one, in order that 
the lifting should be constantly the same ; 2d, that the teeth 
should all be of an equal length, in order that the fall should 
invariably be the same ; 3d, that the back of each tooth 
should be an inclined plane, in order to give to each tooth the 
same thickness towards the point, so that each should exer- 
cise the same friction on both surfaces of the cylinder ; 4th, 
that the small columns which support the teeth should be 
uniform, and well-polished, so that the cylinder could not 
reach them in any case, as this would produce great irregu- 
larity in the movement of the watch. 

1st. — Tool for Uniformly Inclining the Teeth of the Cylinder 

Wheels. PI. YI. 

Figure 9 shows the tool seen in elevation and profile from 
the side, a, 6, of Figure 10. 


Figure 10 shows the same tool seen in front, from the 
side of the artisan during the working. 

Figure 11 is the elevation and profile of the same tool, 
seen from the side, c, d, of Figure 10. 

Figure 12 shows the same tool, seen in front, from the 
side opposite the workman. 

Figure 13 is the same tool, seen above, or a bird's-eye view. 

The same letters designate the same pieces in the five 

This tool is all of brass, with the exception of the screws, 
and a few pieces which we shall mention. 

The frame, A, A, is nearly square ; it bears an opening, 
L, L, L, L, in which a piece of the same form and the same 
thickness as the frame moves, but which is shorter than the 
notch, in order to give it the facility of ascending and de- 
scending when impelled by the adjusting-screw, Gr. The 
four steel bands, /,/,/,/, two of which are fixed on the 
front, and two on the back of the tool, each by two screws, 
form the slide between which the piece, B, moves. This 
piece, B, carries a bridge, M, at the extremity of which a 
puppet, 1ST, is riveted, which receives a small turning-tool, 
P, that is fixed at a suitable point by the adjusting-screw, 0. 
This bridge is fixed on the plate, B, by two adjusting- 
screws and one or two chicks. 

The piece, B, bears upon its other face (Fig. 11, 12, and 
13) a piece, Q, upon which another puppet, E, is riveted, 
which receives the turning-tool, T, fastened by means of 
the adjusting-screw, S. 

It is almost superfluous to add, that the two turning-tools, 
P and T, should be exactly opposite, and that a small, shal- 
low hole should be pierced at the end of each to receive 
the ends of the two pivots of the cylinder- wheel. These 
two turning-tools are of steel. 

The frame of the tool, A, A, bears a rack, D, and a driv- 

214 the watchmaker's manual. 

ing-wheel, E. A horizontal opening is made beneath the 
rack, D, in the frame, which receives a rectangular piece 
riveted with the rack. The whole is fastened by a screw, 
g, which traverses, — 1st, a steel plate which we see in 
front of the rack ; 2d, the rack and the rectangular piece ; 
3d, another steel plate, J (Fig. 12), which serves as a screw- 
nut. By this means the rack can be moved to the right or 
left, according as it is impelled by the driving-wheel, E, 
which is moved by the knob, F. 

The frame of the rack bears a piece of steel, C, U, in the 
upper part, which is called the branch; this moves circularly 
on the screw, h. This piece is of the form represented in 
the figure; it is thinned off in the parts approaching the 
turning-tools from C, as the dotted lines indicate. This 
branch passes between two pieces of hard-tempered steel, 
one of which, I, I, is fixed on the body of the frame, A, A, 
by twp screws, and the other, V (Fig. 13), in the form of a 
bridge, is fixed upon the first by two screws. 

A small piece of steel, bearing a little raised arm, is 
placed above the piece, I, I, as may be seen in Fig. 10. 
This piece bears an oblong hole (Fig. 13), and is fastened 
by a screw ; it can be advanced or drawn back at will by 
means of a pin, which may be seen in the hole, and which 
prevents it from turning. This piece serves to hold back 
the file which, if it were free, might spoil the tooth follow- 
ing the one which is worked. 

This tool is placed upon the ordinary centre-lathe. The 
turning- tools of this lathe enter into the holes m, and n, 
which are seen in the two profiles (Fig. 9- and 11). These 
two holes should be placed at the two extremities of a right 
line parallel to the upper surface of the frame, a, c. 

This being understood, we will describe the operation. 
The workman places his finger on the end, U, of the branch, 
to cause it to rise, after having placed the tool on the lathe ; 


he then places the cylinder- wheel between the two turning- 
tools, P and T, and brings it forward in such a manner that 
it lightly touches the piece, B, which he raises in order that 
the wheel may rest the greatest part of its circumference 
on it, and thus be better supported. He next advances or 
draws back the branch, in such a manner as to support the 
tooth, and to raise it more or less in order to incline the 
plane more or less. 

All being thus arranged, he files all the part which pro- 
jects beyond the pieces I and V, and then passes to a 
second tooth without disarranging anything except the 
branch, which he detaches from the tooth just worked, in 
order to pass it beneath the following one. By this method 
the teeth will all obtain the same inclination. 

2d. — Tool Designed for Two Uses, — 1st, to Reduce the Teeth or 
the Hammers to an Equal Length ; 2d, to Form the Inclina- 
tion of the Back of the Tooth. 

The tool we are about to describe is likewise of brass, 
with the exception of the screws, and a few pieces which 
are of steel, and which we shall point out. 

Figures 14, 15, and 16 (PI. VI.) represent the tool in its 
natural size, and in three different positions. 

Figure 14 gives it in such a manner as to show the 
small lathe in front. 

Figure 15 gives a bird's-eye view of it when it is placed 
on the vise and is ready to work. 

Figure 16 represents it in front, in the vise, as it is pre- 
sented to the artisan during the working. 

The same letters indicate the same pieces in the three 

The frame, A, of the tool has a vertical grooving in its 

216 the watchmaker's manual. 

lower part, in winch a slide, B, moves, which can be raised 
or lowered at will by the adjusting-screw, C. 

The part, B, of this slide bears a horizontal grooving, in 
which another slide, F, moves, which advances or re- 
treats to approach or recede from the frame, A, by means 
of the adjusting-screw, E, and is fixed at the proper 
position by the screw-nut, K, which presses the piece, 
a, against the lower part of the slide, B, by drawing the 
piece, F, which rests on the upper part of the same piece, 
B. The upper part of the slide, F, has a fork, M, which 
receives a tenon, M, that forms a part of the small lathe, 
D, D. 

This small lathe, D, D, has two puppets, whose turning- 
tools are of steel, constructed as in the small lathe described 
in the preceding tool. The adjusting-screw, R, S, serves to 
fasten them. The screw that rests against the frame of the 
tool is designed to advance or remove the turning- tools of 
this frame as may be required. 

The frame is surmounted by a thick piece of steel, H, 
which bears an arm, T, shown in Fig. 16. This piece is 
tempered hard, and is fixed on the frame by two strong 
screws (Fig. 15). We see (Fig. 14) that this piece, H, is 
notched to permit the passage in this aperture of the teeth 
of the wheel, and a small steel rest, I, I (Fig. 16), which is 
moved by the adjusting-screw. The tooth of the wheel 
reposes on this rest during the working. 

This understood, the tool is worked in the two cases 
in the following manner : — 

To Form the Inclination of the Bach of the Tooth. 

The wheel is placed between the turning-tools of the 
small lathe, D, D, in the proper direction, its crown passing 
into the notch, I, so that the tooth resting by its arm upon 


the small rest, I — the wheel presents the back of the tooth 
to the upper part of the steel-piece, H; that is, the in- 
clined plane formed by the first tool (described Fig. 9, 10, 
11, 12, 13) must rest on the small piece, I. The lathe is 
then raised by the aid of the adjusting-screw, C, and is in- 
clined to the suitable position by the screw, G. 

This done, the tooth is found, the point of which presents 
the smallest surface, and the wheel is raised until the file, 
guided by the steel-plate, H, reaches this surface ; and by 
making all the teeth to pass in succession, an equal thick- 
ness is given to this point, and the back of all the teeth are 
equally inclined. 

To Reduce the Teeth or Hammers to an Equal Length. 

The cylinder- wheel is placed on the small lathe, between 
the turning- tools, P, Q, in the inverse direction to that 
which we have mentioned above; the lathe, D, D, is re- 
moved by the screw, G, so that the tooth rests by its arm 
on the small support, I, the point of the tooth or ham- 
mer being in air. All the teeth are then passed succes- 
sively by drawing back or advancing the lathe until the 
shortest, which is on a level with the upper part of the steel- 
piece, H, shall be encountered. This point found, each 
tooth is passed in succession on the same rest, I, and all 
that part is filed away which projects beyond the piece, H; 
in this manner an equal length is secured to all the teeth. 
The file cannot slide against the wheel during this opera- 
tion, as it is held back by the projecting arm, T. 

3d. — Tool for Polishing the Columns of the Cylinder Wheels. 

This tool is of brass, like the preceding ones, with the 
exception already indicated. It is engraved here in its 


218 the watchmaker's manual. 

natural size, the same letters representing the same pieces 
in the three figures. 

Figure 17 shows the tool in elevation placed on the rise 
by its foot, Gr, and seen from the side of the workman. 

Figure 18 shows the same tool seen on its opposite sur- 
face, in order to explain the adjustment and the utility of 
the slide-rest, E, E, which Figure 19 shows in front, as seen 
from the end, H. 

The tool is a small chuck-lathe, whose frame comprises 
the body of the lathe, A, the foot, Gr, the puppet, B, which 
carries the steel turning-tool, C, which is fixed at the proper 
point by the screw, I, and the second puppet, M, to receive 
the neck of the arbor, H, L. . 

This second puppet is formed of two parts; of which 
the one, M, of brass is of the same piece as the rest of the 
frame ; and of a second part, P, of steel, which is fixed by 
two screws on the puppet, M. 

The slide, F, E, H, is fastened on the frame of the tool 
by the two screws, S, S, which are screwed into the frame. 
These two screws pass freely, and without play, into two 
oblong holes, K, E, so that the part, H, E (Fig. 19), which 
turns at right angles towards the puppet, M, can easily ap- 
proach or recede from this puppet by means of the adjust- 
ing-screw, F, when the two screws, S, S, have been loosened, 
which are fastened after the slide has been drawn to the 
proper point, relatively to the wheel which is to be 

It is, doubtless, superfluous to remark, that the holes 
pierced in the puppet, B, in the second puppet, M, in the 
steel plate, P, and in the head of the slide, E, E, at the 
point, H, should all be in the same right line perpendicular 
to the surface of the plate, P. 

The mandrel of the chuck-lathe is of tempered steel, and 
only extends, properly speaking, from the point, J, to the 


turning-tool, L, which is received in a hole pierced at the 
end of the turning-tool, C. 

This mandrel is conical in the part which passes through 
the plate, P ; it is cylindrical in the rest of its length, 
although of different diameters. The centre of the mandrel 
is pierced with a cylindrical hole through a great part of 
its length, reckoning from the point, J. A set of cylindri- 
cal cutting-files, which enter closely by their handle or rod 
into the hole of the mandrel, are fastened in it by an adjust- 
ing-screw, a. A roller, N, of brass, is placed on the ex- 
tremity of the mandrel at L, and is fastened by the adjust- 
ing-screw, 0. 

The cylinder- wheel is placed flatwise against the front of 
the slide at the point H, at the side of the cutting-file ; the 
slide is then advanced, or drawn back, by means of the 
adjusting-screw, F, until the base of the cylinder, which forms 
the cutting-file, comes exactly beneath the tooth, so that it 
does not leave any projection or unevenness against the 
tooth, and that this tooth seems placed flatwise on the top 
of the small column which supports it. The tool being thus 
arranged, a horse-hair drill-bow is placed on the roller, and 
the cutting-file is turned with one hand, while the other 
guides the wheel in such a manner as perfectly to form both 
the small column and the aperture in the form of a U, 
beneath the tooth or the hammer. 


This tool, which is seen in perspective in PI. Y., Fig. 10, 
is described by Berthoud as follows : 

" The part A is made of two pieces which form a jaw 

220 the watchmaker's manual. 

resembling that of the levers for equalizing fusees, with the 
exception of opening perpendicularly to the arm, C, in 
order that the different sizes of the squares of the fusees may 
change the centre, A, of the lever, C, as little as possible. 
The square of the fusee enters into the square hole, A, and 
this jaw is closed by means of the screws, B, b, so that the 
square of the fusee is drawn along with the lever. The arm, 
A, C, of the lever, is in equilibrium with the ball, D, when 
the slider, E, F, is removed. 

" The arm, C, is graduated in its length in such a 
manner that when the slide, E, with the weight, F, which it 
carries, is placed on any division such as 3, 7, 12, etc., to 25, 
we shall have the number of drams which must be placed 
at D to produce an equilibrium with the weight, F. 

u rp graduate this arm, I fixed the jaw, A, upon the 
square of a fusee ; this square was of a medium size, the 
fusee turned freely in its frame without a chain or com- 
munication with the spring; I then brought the arm, A, C, 
into perfect equilibrium with the weight, D ; I suspended a 
small balance-plate at D, on a small grooving, d, made in the 
lathe with the point of a burin, in such a manner that its 
distance from the centre, A, of the lever was exactly four 
inches ; and to prevent the weight of the plate from destroy- 
ing the equilibrium, I attached a small piece of brass to 
the other extremity of the lever, C, which gave equilibrium 
to the balance-plate. All being thus arranged, I replaced 
the slide, E, with its weight, F; I then put one dram in the 
plate and moved the slide, E, until it was in equilibrium with 
the weight of this, when I traced a division and marked 1. 
This done, I added one quarter of a dram to the weight 
in the plate, and moved the slide until it was in equilibrium 
with this weight ; then marking a division extending across 
one quarter of the width of the arm, to designate the 
quarter of a dram. I again added a fourth of a dram and 


found the equilibrium, then marked a division extending 
across half the width of the arm, to designate half a 
dram, then added the same quantity again, and marked a 
division of three-fourths. This done, I added one fourth 
of a dram more to the weight in the plate and marked 2 
across the entire width of the arm, to designate two drams ; 
and, thus adding quarters of drams in succession, I gradu- 
ated the whole length of the arm. 

"It is evident from the construction of this instrument, 
that if it is adjusted to the square of a fusee mounted in its 
frame with the spring and chain, and the slide, E, is moved 
to any division, 5 for instance, to produce an equilibrium 
with the spring, this number will designate the force of the 
spring, in equilibrium with 5 drams placed at the distance 
of 4 inches from the centre of the fusee ; for the force of the 
spring represents here the weight that was placed in the 

We mentioned this instrument in Chapter Eighth, when 
speaking of the means of finding the weight of a balance by 


This improvement (see Figs. XL, XII., XIII, XIV., XV., 
XVI., PI. V.) consists in having found the means of substi- 
tuting a file (Fig. 11) that is flat on one surface which is cut 
very smooth, and the other surface of which is round and 
polished. The small figure, m, indicates the transverse sec- 
tion of this file. We have substituted this file, E, for the 
file, Q, which is generally used by the finishers of teeth, and 
the section of which is shown in the small figure, n. This 
file is represented here in its natural size ; it is cut with 
much difficulty on the two circular surfaces, a, b 7 c, c£, which 

222 the watchmaker's manual. 

renders them very costly ; besides which, however many 
one may have, he is never sure that the assortment will be 
sufficient. The files of which we speak are easily made ; 
five or six, at the most, are sufficient for a full assortment ; 
only vary in respect to size, and they are inexpensive. 

In making use of a flat file for rounding the teeth by the 
aid of a machine, we see that it must imitate in its move- 
ment the hand of the workman that rounds them with the 
ordinary file, and that simultaneously communicate a back- 
ward and forward, and a nearly semi-circular movement. 
These two movements are difficult to obtain at the same 
time, and a workman must possess great skill in order to 
succeed in them without a machine ; this operation, there- 
fore, is rarely executed with regularity. 

To succeed in giving to the file these two indispensable 
movements, while using the ordinary machine for finish- 
ing teeth, we employ a mechanism, which we place on the 
hand which carries the rounding-off-file, in order to com- 
municate to the latter a semi-circular and alternate move- 
ment by the backward and forward impulse which the 
workman necessarily gives to the hend. We make no 
other change in the instrument. As this mechanism is 
little known, we shall describe it in detail. 

Figure 13 represents the section of the hand, taken in the 
middle of its length. 

Figure 12 shows the top of the hand which carries the 
rounding-off-file. The same letters indicate the same pieces 
in both figures. 

The wheel, A, has eleven teeth ; these are cut, and it is 
held back by the catch, B, which is continually impelled 
between two teeth by the spring, 0. This wheel is moved 
by a wheel-click-pin, placed on the upper part of the 
machine ; this passes through the hand by the notch, D, and 
comes to encounter the tooth of the wheel. This wheel 


is inclined when the hand goes forward, and resists when 
it moves backwards ; it is only then that the wheel turns. 

The details of the wheel-click-pin are shown in Fig. 14. 

The number of the teeth of the wheel, A, appear arbitrary 
at first sight ; yet if attention is given to the effect which it 
should produce, it will easily be perceived that the number 
of teeth should be uneven. For this, the number eleven 
seems suitable, in order that the wheel -click-pin may en- 
counter but one tooth, and that the rotary movement of 
the file may be made imperceptibly. 

The lever, E, F, has its centre at E ; it is moved by a pin, H, 
which is fixed vertically on the ratchet-wheel, A, and which 
enters into the notch, Gr, Gr, of this lever. This pin procures 
to the lever an alternate swinging movement from the right 
to the left, and from the left to the right, in proportion as 
the wheel turns. The centre, E, of the movement of this 
lever can approach or recede from the wheel, A, at will, by 
means of the adjusting-screw, L, which causes the piece, I, 
to move in the slide, K, K, which is fixed on the hand. 
By drawing the centre, E, nearer to, or further from the 
wheel, A, the extremity, M, of the lever is caused to describe 
a lesser or greater arc ; b}^ this means a rotary movement is 
given to the file which is greater or smaller, according as 
may be required in the different operations of rounding off 
the teeth, as we shall see in an instant. 

This lever, E, F, carries a rack, M, at its extremity, 
whose teeth are beneath, so as to work into the pinion, U, 
whose axle carries the rounding-off-file. One of the pivots 
of this pinion rolls into the bridge, T, the other passes through 
the bridge, Y, and emerges to carry squarely the apparatus, 
X, Y, which bears the file, Z. The thumb-screw, a, serves 
to fix the apparatus on the square part of the axle of the 
pinion. The adjusting-screw, b, raises or lowers the sup- 
porting-plate, Y, in which the file is fixed by its extremity 

224 the watchmaker's manual. 

as ill a handle, by the thumb-screw, c. The adjusting-screw, 
b, causes the file to approach or recede from the axle of the 
pinion, as may be required in one of the three cases which 
may be presented in the rounding off, as we shall presently 

The number of the teeth of the rack, M, is arbitrary ; it 
is in proportion to the number of teeth given to the pinion, 
and should be such as to cause the pinion to make more 
than a semi- revolution in its movement. 

The rack carries two bridges ; one, Q, is fastened by two 
screws, the other is a little riveted block which is seen near 
the letter G; between these two bridges is the cylinder, P, 
whose pivots roll in these bridges ; this is designed for the 
following purpose. The rack is at the extremity of the lever, 
E, F, which is so flexible on account of its length, that it 
would be thrown out of gear if we did not take the pre- 
caution of covering it by a bridge, S, which confines it in 
the gearing, while the cylinder, P, is placed on the rack to 
diminish the friction. 

Figure 14 represents separately the wheel-click-pin which 
sets the whole mechanism in action ; this is fixed on the 
frame of the machine for finishing the teeth, beneath the 
hand. The end, A, of the pin passes through the longitu- 
dinal aperture, D, of the figure 12, to cause the ratchet-wheel 
to turn. This pin is hinged at the point E (Fig. 14), and 
cannot move backward, as the end, B, rests upon the solid 
part of the tool, and is always kept in this position by the 
spring, C. When the file recedes, a tooth of the ratchet- 
wheel encounters the pin in front, the latter is immovable, 
and the pin is forced to recoil. When, on the contrary, 
the file advances, its pin touches the tooth of the ratchet- 
wheel from behind; it inclines, while the ratchet-wheel does 
not move ; and when the pin has passed beneath the tooth, 
it rises up again and is brought back to its position by the 


action of the spring, C. We see at E, F, a part of the 
frame of the ordinary machine for finishing teeth. 

This new hand is used in the following manner: — When 
the teeth are ready to be rounded off, the hand is set on the 
tool, after having placed the pin and fastened it by the pin, 
E (Fig. 14), in front of the rounding- wheel : a file is chosen 
whose width easily encircles two teeth without touching 
either of the others during its semi-circular movement, and 
the file is advanced or drawn back by means of the 
adjusting-screw, b (Fig. 13), until it can exactly round the 
half of each tooth ; and it ;s clearly evident that, when the 
wheel has made a revolution, all the teeth will be rounded. 

It would also be possible, with the same machine, to round 
each tooth by a single stroke, and by a single movement of 
the file, while, in the preceding operation, two are required 
for the rounding of each ; but for this it would be necessary 
to use a file so narrow as not to touch the two adjacent teeth 
in its circular movement. A circular rounding would be 
obtained by this operation, but the form would be defective 
and it would not accomplish its purpose. . 

We have proved that these teeth should be rounded in 
an epicycloid. Heretofore one could not be assured of ob- 
taining this exact form in practice ; but the curve which we 
give, by the aid of the hand which we have just described, 
approaches so nearly to it as to show no perceptible differ- 
ence, and it would probably be possible to give the pre- 
cise form to the teeth by the absolute perfection of this 

If the form of the pinion, or the position of the wheel, 
demand that the teeth shall be still more a point-tool, to use 
the expression of the workmen, the file must encircle three 
teeth instead of two, the same precautions being taken as 
in the first example. 

Figure 16 indicates the course of the file in the three 


226 the watchmaker's manual. 

cases which we have just surveyed. Care must be taken 
that the arc described by the rounding-orY-filc be greater 
in proportion to the greater number of teeth which it 
encircles in its course. To demonstrate this, take the 
three circumferences, G, H, I ; A, E, F ; D, B, C ; the first 
of which encircles one tooth, the second two, and the third 
three. It is evident that when the radii include three teeth, 
they form a greater angle than when they include but two, 
and still greater than when they include but one ; for this 
angle, whose apex is beyond the circumference at the point, 
K, has for a measure the difference of the half of the convex 
arc from the half of the concave arc comprised between the 
radii. This difference increases with the number of teeth 
included ; that is, the convex arc increases while the con- 
cave arc diminishes as they form together the entire cir- 
cumference described by the movement of the file. 

As the rounding-off-file describes a larger arc in propor- 
tion as it encircles a greater number of teeth, we could not 
give it a uniform course ; it was therefore important to cause 
it to describe larger or smaller arcs as might be required. 
This we have done by making the point, E (Fig. 12, 13), 
the centre of motion of the rack, E, F. Figure 15 will 
serve to demonstrate this truth. 

Let us suppose C, D equal to the diameter of the circle 
described by the pin, H (Fig. 12), which impels the lever 
that carries the rack ; we still suppose A to be the centre 
of the lever, A E, A F, the two radii of the arc described 
by the lever in its swinging movement, which pass by the 
two extremities of the diameter, C, D ; the rack will then 
describe the arc, E, F. If we change the centre to B, the 
diameter, C, D, being still the same, the radii, B G and B F, 
which pass by the points C and D, will include the arc, Gr F, 
described by the lever ; and this arc is the measure of the 
angle formed by the lever, when its centre is at the point B ; 


but this arc, Gr F, which is the measure of the angle, Gr, B, F, 
is smaller than the arc, E, F, whicli is the measure of the 
angle, E, A, F. The arc described by the extremity of the 
lever is therefore greater in proportion, as its centre ap- 
proaches the centre of the wheel which carries the pin, H, 
and smaller in proportion as it recedes from this centre ; but 
the greater or smaller is the arc described by the rack, the 
greater or lesser will be the movement of the pinion into 
which it works, and, consequently, the greater or smaller 
will be the arc described by the file. The hand (Fig. 12) 
cannot therefore pass from the mechanism designated by the 
letters I, K, K, L. 

The experiments required for finding the exact point 
indispensable for obtaining the kind of teeth that may be 
wished will not occupy much time ; experience has taught 
us that much more is often required, in the old system, for 
finding a suitable rounding-off-file, which one may not 
always possess. 

In the tools for finishing the teeth, there is no regulator 
for presenting the tooth at the precise point on which the 
file should act. The tongue, a, which the file carries as a 
regulator is used for this purpose, but if this tongue be too 
thick or too thin, the file acts more on one side than on the 
other, and the wheel is unequal. Our system had not even 
this resource, and we perceived the need of a certain regu- 
lator ; the support (PL II., Fig. 17) which is used in ordinary 
tools for teeth, seemed to us to be suited to this purpose. 
This support enters as a slide by its two arms, A, B, into the 
box which slides on the branch of the lathe which supports 
the wheel. The arbor of the wheel enters into the hole, D 
of this support and rests against the plane of the round plate, 
E ; it is confined in front by a piece which comes to rest on 
the other surface. 

We have formed our regulator of this same support with 

228 the watchmaker's manual. 

some few changes, as represented in Figure 16. The form 
is the same ; we have simply enlarged the branches to adapt 
the regulator to them. The arms, A, B, are larger, in order 
more easily to make two notches, C, D, in them ; in the 
notch, D, a sliding-piece of brass moves, which carries the 
axle of the slide, E, F, and which can ascend or descend 
by means of the adjusting-screw, Gr, to fasten the teeth of 
large or small wheels ; the notch, C, is designed to receive 
the neck of a screw whose head is behind, in order to pre- 
vent the end of the slide, E, from moving from the plate. 
The slide, E, F, is straight and carries a box, H, which 
slides along its length, to which the catch, I, is fastened ; 
this box is moved by an adjusting-screw, K, to present to 
the file in a suitable position, but always diametrically 
opposed to the action of the file, the teeth which are to be 
rounded. The slide is constantly pushed upward by the 
spring, L, which presses against a pin, M ; the catch, I, is 
freed by pressing the finger on the end, E, while the wheel 
is turned with the forefinger. We have designed this 
piece on a large scale, in order that all the parts might 
be distinct. This same mechanism can be easily applied 
to the piece which supports the crown-wheels. 



We have thought it advisable to add to the preceding 
chapters descriptions of some patents which have fallen into 
forfeiture, and which may convey some useful information, 
or suggest some available ideas. We must apprise our 
readers that we only transcribe them as documents which 
it is sometimes necessary to consult. 

Patent of invention, taken for five years, for a mechanism 
designed to correct the striking -tvork of clocks, by M. Robert 
Houdin, of Paris ; dated May 22, 1840. 


The weight of a hammer tends to carry it beneath a 
detent when the latter is sufficiently raised to require its 
effect, when otherwise, it rests inactive above it ; the pins 
fixed on the minute-hand-pin raise a second detent, as usual, 
every hour and half-hour ; this, in its turn, raises the first 
detent by the aid of a longitudinal piece, yet not high 
enough to permit the entrance of the first-mentioned 
hammer beneath it. 

A pin, fixed on the hour-wheel and representing noon, at 
each turn of the wheel, raises the second detent by means 
of another pin which is fixed on this piece, somewhat 
higher than usual ; the hammer then, by its weight, falls 
beneath the detent and hinders it from falling back into the 

230 the watchmaker's manual. 

notches of the notch- wheel, and the striking- work continues 
to strike until a pin frees the hammer and permits the detent 
to stop the train after twelve has been struck ; if the twelve 
of the striking- work, and the twelve of the movement agree, 
but twelve blows will be struck as the hammer will then 
be raised. 

September 18, 1840. Patent of addition and improvement. 

These new arrangements, like the former, are designed 
to cause the striking- work to accord with the hands once in 
twelve hours, in case that it miscounts. 

The advantage of these arrangements is, that when the 
striking- work miscounts it is corrected at noon or at mid- 
night, as the notch-wheel is then forced to cause as many 
strokes to be struck as may be necessary to strike the true 
hour ; thus, if when the hands point noon or midnight, the 
notch- wheel is in a position to cause half-past twelve to be 
struck, the arrangements already described will make it 
strike eighty-nine strokes in order to make it agree with 
the hands. 

Whatever may be the advantage of having a clock which 
cannot miscount during more than twelve hours, the result 
thus obtained presents the inconvenience of causing the 
spring of the striking-work to go faster than that of the 
hands, and .thus demands, in a piece liable to miscount, a 
more frequent winding of the one than the other ; besides 
which it is very annoying to be awakened at midnight by a 
prolonged striking. 

To avoid these inconveniences, we would substitute for 
the preceding arrangements, these which we are about to 
describe, and which are designed to stop the striking-work 
when it has struck twelve hours, and to cause it to wait for 
the hands when they mark half-past twelve. 


The modifications which produce this stoppage of the 
striking-work consist in the elongation of the beak of the 
detent, in which elongation a notch is made, in which 
the ordinary detent begins or ends ; and in the placing 
of a pin on the crown of the notch-wheel immediately before 
the notch that follows the projecting arc which causes twelve 
to be struck ; when the twelve strokes have sounded, this 
pin, which is terminated by an inclined plane, elevates the 
detent still more by sliding beneath its blade, so that the 
pin of the cog-wheel, which passes freely into the notch of 
the elongation of the detent during the striking of twelve 
as well as the preceding hours, then comes to prop against 
the solid part of the detent, placed beyond the notch, thus 
checking the striking- work after it has struck twelve hours, 
whether it has or has not miscounted. 

A pin is fixed on the flat of the hour-wheel which, at 
twelve or half past, attacks a projection placed on a detent, 
and raises the detent far enough to permit its blade to pass 
above the pin of the notch-wheel and to fall back into the 
notch beyond it ; this replaces the pieces in their normal 
state, and permits the striking-work to act as usual, because, 
when it has not struck twelve hours, the detent acts as if its 
beak had not been lengthened, the pin of the cog-wheel 
passing freely into the notch. 

When the clock miscounts, the discord will last until the 
clock shall have struck twelve hours, when it will be cor- 
rected, as then the blade of the detent, raised by the pin of 
the notch-wheel, will draw the end of the beak of the detent 
upon the course of the pin of the cog-wheel, and will hinder 
all further movement of this wheel until the hands, which 
continue to move, mark twelve, or half-past twelve. The 
pin of the hour-wheel then attacks the detent by the pro- 
jection, and thus raises the detent far enough to cause the 
blade to pass above the pin of the notch-wheel, thus per- 

232 the watchmaker's manual. 

mitting the striking-work to move in unison with the 

Patent of invention, for five years, for improved movements of 
Clock-work, by M. Brocot, of Paris ; dated October 9, 1840. 

The first arrangements of this patent relate to the methods 
of regulating the length of pendulums, and obtaining their 
compensation. M. Brocot, the inventor of the improve- 
ments which we are about to describe, perceived that 
he had been anticipated in the discovery of the principle of 
pendulum-compensations by M. Wagner, he therefore only 
claims the application of the material conditions of this 
principle, which consist in making the great dilatability of 
zinc subservient to the compensation of the pendulum. 
We shall first occupy ourselves with various constructions 
in which this last condition is applied to obtain a double 

In the simplest form, the lower extremity of a rod of zinc 
is linked to a vertical piece which is fixed on the back 
pillar-plate of the mechanism, while its upper extremity 
props against a lever whose centre of motion is at its junc- 
tion with the vertical piece. 

To this lever the pendulum is suspended, whose thread 
or flexible blade passes into a cleft of a circular piece ; the 
lower extremity of this cleft limits the length of the pen- 
dulum, which, in this case, we suppose regulated by a con- 
stant temperature. 

It is evident that if the temperature should increase, for 
instance, the pendulum will elongate, and, consequently, 
that its movement would slacken if the dilatation of the 
zinc rod did not elevate the lever, and with it the pendulum, 
whose length will thus remain the same if the upper end 
of the zinc rod is properly adjusted beneath the lever; and 


we will perceive that the nearer this extremity approaches 
the centre of motion of the lever, the higher will the point 
of the lever be elevated by the same dilatation, and the more 
will the pendulum be shortened. 

To secure the proper adjustment of the zinc rod, an 
adjusting-screw is screwed into a ring-screw fixed on the 
vertical piece, and is linked at its end to the zinc-rod. By 
turning this screw, in contrary directions, the upper extre- 
mity of the zinc-rod is drawn nearer to, or further from, 
the centre of motion of the lever, and is thus placed at the 
point at which the contraction or dilatation of the rod com- 
pensates the contraction or dilatation of the pendulum. 

The condition which permits the regulation of the com- 
pensation and the length of the pendulum at the same time, 
is effected by means of a wheel on the flat of which is a 
spiral groove into which enters a pin fixed upon a piece 
which is movable about a centre. 

It is evident that by turning this wheel, either directly or 
by means of a pinion furnished with a knob, the position 
of the system may so be modified as to regulate the length 
of the pendulum with the greatest precision. As the spiral- 
groove can be composed of a greater or less number of turns, 
it is much superior in this respect to the snail which is 
sometimes used and which cannot make an entire turn, for 
it is necessary to give a great movement to the spiral-groove 
to produce a sensible depression or elevation of the pin, and 
consequently, a corresponding change in the position of the 

The lever, which is movable about a centre and which 
props on the extremity of the zinc rod, follows all the move- 
ments of the system, as well as the pendulum which is 
suspended to it, and whose length is thus regulated by the 
position of the pin in the spiral-groove. 

We must also remark, that though the zinc rod in this 

234 the watchmaker's manual. 

construction seems fastened by its two extremities, the hole 
which the upper screw passes through is sufficiently oval 
to permit the elongation or contraction of this rod without 
inducing the distortion of the vertical piece. 

In case it is found inconvenient to regulate the length 
of the pendulum from the back of the movement, it 
can be done in front by substituting for the pinion 
another pinion whose rod passes through the two pillar- 
plates and is terminated by a square arranged to receive 
a key. 

In the third construction another application of the spiral- 
groove is made ; the pin is placed at the lower extremity 
of the movable piece on the same arbor as the lever ; but the 
movement of the spiral-groove still determines that of the 
piece, independent of the lever, and, by the medium of the 
zinc rod, that of the lever also. 

A fourth construction may be substituted for this, which 
is also designed to regulate the length of the pendulum in 
front of the movement. As in the second construction, the 
piece has two branches, one rests by a pin on a snail or a 
spiral-groove, whose arbor passes through the two pillar- 
plates; the lever props on the zinc rod which transmits 
to it the movement communicated to the piece by the snail 
or the spiral-groove. 

A fifth and a sixth construction represent arrangements 
having the same design, but in which neither the spiral- 
groove nor the snail is employed ; for there is substituted 
an inclined plane which is adjusted to the piece, and 
against which a screw props itself, the movement of which 
causes the inclined plane to slide over its point and deter- 
mines the movement of the piece about the centre; this 
movement, by the medium of the zinc rod, determines that 
of the lever. 

The seventh construction is solely designed to regulat j 


the length of the pendulum by means of the spiral-groove. 
It is composed of a potance whose horizontal branch carries 
the pendulum, while the vertical branch is maintained in its 
position bj a collet which serves, at the same time, as an 
axle to the wheel by a pin placed on the pillar-plate; a pin, 
fixed on the potance, rests in the spiral-groove, the rotary 
movement of which, determiaed by a pinion, raises or 
lowers the potance, and, consequently, lengthens or shortens 
the pendulum. 

Several of the preceding constructions have a click-spring 
which works into the teeth of the wheel, or into those of 
the pinion which carries it. This click is designed to show 
the degree of motion communicated to the wheel, and to 
cause it to retrograde when it has exceeded the point in a 
preceding operation. 

The second arrangement of the patent of M. Brocot is a 
striking-work which offers the advantages of the striking- 
work of the notch-wheel and rack without their incon- 
veniences, as it can never miscount, either when the hands 
are moved forward or backward, or when the mechanism 
is placed in one of those conditions which causes the 
miscount in ordinary clocks. 

Upon the arbor of the striking- wheel is mounted a ratchet- 
wheel of ninety teeth, representing the number of strokes 
which the piece should strike in twelve hours. The detent 
is formed of two branches, one of which is bent and is con- 
centric, in its outer circumference, to the ratchet-wheel at the 
same time that it is below the bottom of the teeth of this same 
wheel, when in a state of repose. Two pins are placed oh the 
minute-wheel which raise the detent at every half-hour. 

A lever is movable upon the same arbor as the ratchet- 
wheel and independently of this wheel, a part of which has 
sufficient weight, when nothing opposes it, to place a pin 
upon a snail which is fastened on the arbor of the minute- 

236 the watchmaker's manual. 

wheel. Upon one arm of the lever is a click whose pin is 
placed between two teeth of the cog-wheel, during the 
repose of the striking-work. When a pin places itself 
beneath a branch of the detent it raises the latter ; another 
branch, bearing a claw at its end, frees the preparation and 
produces what in clockmaking is called the delay. The 
same pin still continuing to raise the detent, the pin of the 
click is extricated from the teeth of the wheel at the same 
time that another pin and the ess are raised by the branch 
of the detent, until the motion at which the pin of the 
minute-wheel ceasing to act beneath another branch, the 
detent falls by its own weight, together with the click, 
whose pin works again into the teeth of the ratchet-wheel. 
In this fall of the two pieces, the detent, placed on the axle 
of the ess, has freed the striking- work, which is then put 
in motion. 

To describe clearly the action of this mechanism, we must 
remark that the two pins, though placed on the same 
diameter of the minute-wheel, are not at an equal distance 
from the axle of this wheel, so that the one of them, which 
is to cause the striking of the half-hours, does not raise the 
detent as far as does the other, which causes the striking of 
the hours ; and that, in consequence, although the other 
effects may be the same, the first pin never raises the ess 
above the lower part of the outer branch of the lever, and 
always leaves a pin there. When the detent escapes from 
the pin of the minute- wheel, this pin, which had rested on 
the lower portion of the lever during this movement, falls 
back upon another portion and determines the arrest of the 

The outer edge of the detent is arranged in such a manner 
that, when the hands are turned back, the minute-wheel, 
which is susceptible of a slight movement on its arbor, recoils 
when one of its pins encounters this edge, and slides along 


the inclined plane, forcing the detent, which is flexible, to 
recoil, until the pin passes beyond the lower edge of the 

It is evident that this striking- work cannot miscount, as 
the action of the snail is conjointly with the hour- wheel. 

In the second, third, fourth, and seventh constructions, 
the spiral-groove is in a frame between a part reserved for 
the escapement-bridge and a short plate. By this arrange- 
ment the escapement-bridge can be taken down without 
fear of affecting the regularity of the clock. 

First Patent for addition and improvement. Nov. 14, 1840. 

This patent relates to more precise methods for regulating 
the length of the pendulums than those already described. 

In these arrangements, which do not exclude the condi- 
tions of the compensation before patented, the spiral-groov- 
ing is replaced by an adjusting-screw of a very fine thread. 
In the most simple application of this, a screw, passing 
through the bearer of the spring-band, which serves as a 
screw-nut, permits the raising or lowering of the latter, by 
means of a knob, and consequently, the shortening or 
lengthening of the pendulum. When this effect is obtained 
by acting in front of the clock, the knob becomes a wheel 
working at right angles with the pinion, whose rod, passing 
through the mechanism, projects on the side of the dial and 
receives from a key the movement which determines that 
of the screw, through the medium of the wheel. 

In a second construction, the precision can be carried to 
exactness by the application of the principle of the dif- 
ferential-screw of M. de Prouy. 

One half of the length of the screw is grooved with a 
thread differing from that of the other half. But this dif- 
ference is very slight ; a hundred threads of the part a, for 

238 the watchmakek's manual. 

instance, corresponding to ninety-nine threads of the part a'. 
The part a has its screw-nut fixed on the escapement-bridge, 
while the screw-nut of the part a' is screwed into the spring- 
band clasp. 

At each turn of the screw, the clasp descends in a quantity 
equal to the thread of its screw ; but at the same time the 
screw winds up a quantity equalling the thread of the fixed 
screw-nut, which is a hundredth less than that of the spring- 
band clasp ; this clasp will therefore be lowered to the 
distance of the hundredth part of the thread of the larger 
screw by an entire turn, and consequently, to make it pass 
over a space of the tenth part of an inch, the screw may be 
caused to make several hundred turns ; a condition which 
permits the length to be determined with mathematical 

In these constructions, a click-spring works into the 
teeth of the pinion ; this is designed to show the number 
of divisions which have been made for regulating the length 
of the pendulum, and to enable it to retrograde when the 
point has been exceeded in a preceding operation. 

Second Patent for addition and improvement. June 20, 1842. 

These new and final arrangements consist : 

1st, In more precise methods of adjustment of the systems 
before patented. 

2d, In an economical process for obtaining the same 

3d, In a new method of facilitating the regulation of 

In the first improvement the spring-band clasp was only 
cleft in the middle for the passage of the suspension-spring; 
much care was necessary in the adjustment of this clasp in 
its frame. 


In the new arrangement the clasp has three clefts ; that 
of the middle still receives the suspension-spring, while the 
two others, made nearly at the edge, form by drawing them 
a little aside, two springs which press on the inner cheeks 
of the frame and produce a good and indestructible adjust- 
ment. In the same manner the clasp was tapped, and an 
easy adjustment without play was impossible; these inconve- 
niences have been remedied by prolonging the arm of the 
clasp ; by cleaving this arm, and then reclosing the cleft a 
little, a good adjustment is obtained; the same effect will 
be produced by cleaving the clasp longitudinally and then 
reclosing the cleft a little. This method seems preferable 
to us, as it is less expensive. 

A suspension-spring with a double band is also used, this 
possesses the advantage of avoiding torsion, and of carrying 
the balance more regularly, but it is very difficult to adjust, 
at least with economy. 

The inventor of these constructions had before employed 
simple springs, but his balances sometimes turned ; this led 
him to suppose that hy hollowing out the centre of the band 
1 he would obtain the same result as with the suspension- 
spring with two bands ; reiterated experiments have con- 
vinced him that this hollowed band possesses the same 

The indicator of M. Brocot, which shows how many 
divisions have been lost or gained, is well adapted to the 
regulation of the lengths of pendulums ; but the numerous 
inquiries which have been made of him to know how many 
divisions should be made in order to regulate a certain 
variation in a given time, have caused him to make some 
experiments which have been entirely successful. A figure 
placed on the dial, and adapted to the length of the pen- 
dulum, indicates the number of divisions which should be 
made for one minute of variation in twenty -four hours, and, 


consequently, the proportional number of these divisions 
for a greater or less variation. 

Patent for Importation, for ten years, by M. Gallard Davies, 
of London, for Clocks running a year without being wound, 
dated February 15, 1841 ; forfeited February 2, 1844. 

My invention consists in the application of a system of 
watch-movement to the fourth and to the last arbor of a 
system of clock-movement ; this permits me to make a clock 
which, in running during twelve months, will require to be 
wound but a single time ; this invention also consists in 
placing the second or the third wheel, or the second and 
third of the said system of clock- wheels, beneath the dial 
and in front of the large pillar-plate, or behind the small 
pillar-plate, or in any case at the outside of the frame. By 
this combination I can obtain a small and portable clock, 
which will only require to be wound once in a year, with a 
single barrel or motive-power for each part of the said clock ; 
that is, one for the movement of the said clock, and one for 
the striking- work ; while those which have before been made 
to run during this time have always been excessively large 
and troublesome by reason of their construction. 

The barrel contains the main-spring, arranged for six 
revolutions, and carries at its circumference the great- wheel, 
divided into one hundred and forty teeth. The second wheel 
has one hundred and ten teeth with a pinion of ten leaves, 
and receives its movement from the great- wheel. 

The third wheel has ninety teeth ; this, although one of 
the principal wheels of the clock, is not placed between the 
two pillar-plates, or in the frame of the clock, as has here- 
tofore been the custom, but quite at the outside of the large 
pillar-plate, and immediately beneath the dial of the cloc'c, 
thus gaining much space. 


In the large pillar-plate, at the circumference of the 
second wheel, a hole is pierced which receives the small 
pinion of ten teeth, that forms the arbor of the third 
wheel. This arbor and this wheel are fixed to the large 
pillar-plate bj two rackets. The arbor of the third 
wheel receives its movement from the second wheel. The 
clock-movement being put together, as we have just said, 
the frame containing a part of the watch-movement, com- 
mencing with the centre- wheel, is fixed to the large pillar- 
plate, by two screws, in such a manner that the pinion of nine 
leaves, forming the arbor of the first or of the second centre- 
wheel, is encountered by the third clock-wheel, which impels 
it and causes its movement. 

It is useless to describe the other watch-wheels, as any 
system with any escapement, commencing with the centre- 
wheel, can be employed ; and when one is sure of having 
put the motive-power which the third wheel possesses, in 
connexion with that of the great-wheel or fusee of any 
ordinary watch, the dimension of the watch system to be 
employed can be easily determined from it. 

The wheels which regulate the velocity relative to the 
hands, and which are technically called the movement, are 
the same as those generally used. 

The arm itself is moved by a small pin which slides into 
a groove made in the dial ; the other end of the pin is 
inserted between the fork. 

It is unnecessary to say more on this article which does 
not form a part of the improvements of the patent. Other 
means may be employed for the regulation of the velocity. 
It suffices to say that, when it is unimportant that the clocks 
should be smaller than those just described, the second part 
of my invention need not be employed ; that is, the placing 
of the second or third wheel with a fusee and chain ; in this 
case the first part of my invention, that is, the application 



of a system of watch-movement to the fourth or the last 
arbor of a system of clock-movement, will be sufficient. 
But I claim as my invention: — 1st, The application of a 
system of watch-wheels (commencing with the centre- wheel) 
to the arbor commanded by the third wheel of a system of 
clock- wheels ; the centre-wheel of the watch system being 
that which is placed on the said arbor, and the wheels being 
arranged in the manner before described, permit me to cause 
the clock to run during twelve months without winding 
more than once. 2d, The manner of placing the wheels 
as has been said before, in order to save space. 

Patent for ten years, for a System of Public Clocks, called 
Polygnomones, by M. Malo, of Paris. Dated July 19, 
1841 ; annulled, by order of the king, September 10, 1.844. 

Several particular properties of this mechanism produce 
a result which the inventor describes as follows : With a 
polygnomone one can, 

1st, Eetrace the hour indicated by a regulating clock 
upon an unlimited number of dials. 

2d, Place these dials at considerable distances, either from 
each other or from the regulating-clock. 

3d, Maintain the most perfect concordance in the indi- 
cation of the hour among all the dials and the regulating- 

A polygnomone is composed : 

lst x Of a motive-power ; 2d, of a regulator ; 3d, of one 
or several groups of conductors, and of dials carrying their 
minute- wheel-work. 

The motive-power is a train entirely distinct from the 
regulating train, it serves to set in motion the conducting 
wires, and, consequently, the hands of the dials. 

Its action is periodical ; it is regulated and moderated by 


the regulating-clock. The motive-train is composed: 1st, 
of a barrel ; 2d, of an intermediate- wheel ; 3d, of a pinion 
carrying a lever with two arms and a crank. The lever is 
held in check by the leaves of a pinion carried by the 

The power of the motive-train is proportioned to the 
resistance to be surmounted ; that is, to the number and the 
dimensions of the dials, 

The regulator is a common clock ; its dimensions are 
rendered somewhat indifferent by the intermediate levers of 
which we shall presently speak ; but this clock must contain, 
or be able to conduct, a pinion of four, six, or eight leaves, 
and each leaf of this pinion must be replaced by the following 
leaf in the interval of a minute. The effects of the motive- 
power and the regulator are combined in the following 
manner : 

The pinion makes a revolution in six minutes, and, con- 
sequently, each of its leaves takes the place of the preceding 
one in the interval of a minute ; and, as the lever is held 
back by one of the leaves of the pinion, it will be disengaged 
at each interval, will make a semi-revolution on its axle, 
and will be again checked by its opposite arm by the follow- 
ing leaf of the pinion, and so on from minute to minute. In 
the same time in which these movements are accomplished, 
the crank passes alternately from one position to another. 

The extremity of this crank enters into a small socket 
connecting two ends of iron- wire, one of which is placed in 
the prolongation of the other. These wires are forced to 
move in the direction of their length, following the swing- 
ing impulse which they receive from the crank. 

I have said that the dimensions of the regulating-clock 
are somewhat indifferent ; I have also said that the dimen- 
sions of the motive-power increase in proportion to the 
number and the size of the dials ; a great disproportion 

244 the watchmaker's manual. 

between the motive-power and the regulator results from 
these two circumstances, and if, on the one hand, the motive- 
power having to conduct several hundreds of dials would 
represent, for instance, the force of a man working without 
interruption, and if, on the other hand, the regulator was no 
larger than an ordinary apartment-clock, it would be neces- 
sary, under penalty of seeing this regulator broken by the 
shocks of the lever of the stop-work of the motive-power, 
to avoid all immediate contact of these two parts of the 

For this I use one or several intermediate levers ; the lever 
of the stop- work, instead of acting directly upon the pinion 
of the regulator, strikes the leaves of an intermediate pinion 
which carries four arms which are shorter and lighter than 
those of the lever. Each of these four arms strikes, in its 
turn, a second pinion carrying four arms still lighter and 
shorter than the preceding ones ; each of these four arms is 
checked by the leaves of the pinion carried by the regu- 
lating-clock. In this manner one can accurately regulate 
the movement of a polygnomone, however colossal it may 
be, by means of a simple watch-movement. It suffices for 
this to place between the double lever and the pinion, a 
proper number of intermediate pinions, as the intensity of 
the forces of these levers always continues to weaken until 
the last, which holds all the others in check by means of the 
pinion of the regulator. 

The conductors are simply iron wires, arranged in such 
a manner that, however numerous they may be, all repeat, 
in the same time, the backward and forward movement 
communicated by the crank. The principal wire attached 
to this crank is subdivided into several other wires, from 
which spring still others, and so on to the last, which 
end in the minute- wheel-works of the dials, the hands of 
which they impel from minute to minute by means of the 


escapement-pieces to which they communicate their back- 
ward and forward movement; this is transformed into a 
rotary movement to turn the hands, by means of a pecu- 
liar escapement which I shall presently describe. The 
changes in the direction of the wires are obtained by 
elbowed levers, whose points of support rest on blades of 
tempered steel, precisely like the points of support of 
the beams of a balance. At the extremity of each con- 
ducting- wire is placed an adjusting-spring designed for two 
purposes : 1st, to keep the conductors constantly extended ; 
2d, to bring back the escapement-piece to the extremity of 
the lifted piece opposed to the traction of the wire. 

To regulate the motion of the crank in rising, another 
wire is placed opposite the first, and in the same direc- 
tion, at the extremity of which a spring or counter- weight 
acts, whose power produces an equilibrium among all the 
springs of which we have just spoken ; or, which is still 
better, instead of the spring or counter- weight, another 
system of conductors or of dials analogous to the first is 
placed beneath the second wire, taking care that the sum of 
all the aggregate resistances of the second wire shall be in 
perfect equilibrium with the sum of all the resistances of 
the first wire. The impulse-crank will thus have no other 
resistance to overcome than that of the friction of the wires 
and the minute-wheel-works, which is but trifling. The 
dials and their minute-wheel-works may have two hands, 
for hours and minutes, and may be of any size. 

In the minute-wheel-work, the escapement-piece which I 
have mentioned is fixed with an arbor on which it turns. 
To the arm or lever of the escapement, which forms part 
of the same piece, is attached the conducting- wire as well 
as the adjusting- wire, drawn by a spring. 

Three small groovings, whose union forms a Y, are made 
in this piece which they traverse in a zigzag manner. 

246 the watchmaker's manual. 

A wheel, carrying two pins, receives the action of the 


1st. To regulate the action of the motive train, a fly of 
a certain weight is added, which, at the end of its course, 
will transfer its acquired force to a spring which pre- 
serves it during the minute of repose, and then restores it 
to the fly to aid its departure, and so on from minute to 

I also employ for the same purpose, in some cases, a 
heavy pendulum whose oscillations from minute to minute 
perform the functions of the fly. 

2d. The minute- wheel- works of each dial should be so 
arranged that the hands of the dial can always be set at the 
hour if deranged by any accident. 

3d. Instead of a weight, I can employ any other power 
if necessary, whether air, water, or steam, to set the polyg- 
nomone in motion. 

Applications of the Polygnomone. 

The polygnomone, furnishing the means of indicating the 
hour in all the rooms and halls of a building, will be espe- 
cially applicable to hospitals, barracks, schools, manufac- 
tories, hotels, and public buildings in general. 

Its use may even be extended to the entire district of a 
city, in which each room of every house may have its dial. 

Patent for Invention, for five years, for a Dead-heat Escape- 
ment-wheel, by M. Delor. Dated September 28, 1842. 

The principal piece of this escapement is the arbor of the 


balance, which carries two rollers serving, in turn, as lever 
and dead-beat, while this balance describes its arc of vibra- 

The escapement-wheel is of tempered steel, in the usual 
form, and cut in an inverse direction. 

The arbor of the balance is placed at a suitable distance for 
working into the escapement- wheel. A tooth seizes the lever 
of the upper roller and carries the lower roller on the next 
tooth ; this lower roller holds the wheel in repose while the 
balance makes its vibration. 

The two rollers form a cylinder, horizontally, whose 
diameter is the half of the distance from one point of the 
tooth of the escapement-wheel to the other point, without 
regard to the size of the wheel and the number of the teeth. 
The distance between the two rollers is eight degrees ; it is 
through this that the wheel escapes to the right and the left. 

This escapement, which is easily executed and very suc- 
cessful, sustains its motion and its regularity better than the 

Patent for Invention, for five years, for a Balance marking the 
fixed Seconds, by MM. Berolla, of Paris. Dated Oct 15, 
1842 ; annulled by order of the king, May 21, 1845. 

This mechanism is composed of a ratchet-wheel of sixty 
teeth, and of a click ; the whole being placed at the centre of 
the pendulum-ball of the balance ; a lever, which is placed 
higher, works into the teeth of the wheel by an end armed 
with a small spring ; the other end of the lever comes 
to the top of the small fork of the pendulum, and the 
vibrations of the balance are maintained by this lever, 
which, after having forced one tooth of the wheel placed at 
the centre to escape, conducts the balance to the right and 
left as usual. There are two banking pi is which hinder 

248 the watchmaker's manual. 

the lever from making a longer course than is necessary to 
cause the escaping of the tooth; the lever sustains the 
vibrations of the balance by these pins. This mechanism 
is applicable to every description of balance, and to all 
clocks, and can be placed in the interior or at the exterior 
of the balance ; there is a second-dial and hand at the centre 
of the balance. 

The most important point of this invention is the lever ; 
which is conducted to the right and left by the little fork 
of the pendulum, and which, after having caused the second- 
wheel to move, moves the balance as usual. 

Patent for Invention, for five years, for Tools suited to the 
Manufacture of the Wheels of the Cylinder- Escapement, by 
M. Rogier. Dated August 27, 1844 ; expired July 28, 

This invention is designed to enable all workmen to 
manufacture cylinder-escapements with facility, and consists 
in processes of execution, and tools of the greatest simplicity 
for the construction of the escapement- wheel. 

One of these tools is designed to disengage mechanically 
the semi-circular spaces of the teeth of the wheel when the 
wheel is cut ; the other is used to facilitate the regularity of 
the extreme inclination of the teeth. 

PL V., Fig. 17, 18, represent the elevation and plane of 
the space-column tool. 

Fig. 7, 8, 9, the principal parts in detail. 

The design represents the apparatus on a scale large 
enough clearly to show the forms and arrangement. A is 
the fixed part of the space-column tool; it is placed by the 
ear, downward at a, between the jaws of the vise. 

The puppet, b, is penetrated by the cylindrical turning- 
tool with friction, which is then received by the opposite ex- 


tremity, into a conical collet fastened into the body of the 
upright, A. 

A small screw, #, passing through, the axle, e, serves as an 
abutment against the upright, A. 

The axle, e, is terminated by a cylindrical cutting-file, h, 
whose diameter is determined by the space to be preserved 
between each tooth. 

Beneath the frame, A, is fixed a slide, B, which is pro- 
longed at right angles outside the frame, A. Two thumb- 
screws, t, 4, secure the maintenance of the slide, B, when its 
position is regulated, permitting it, however, to receive the 
backward and forward movement communicated to it by 
means of the screw-nut, j\ and the adjusting-screw, K. 

The vertical prolongation of the slide, B, assumes the 
trapezoidal form, to serve as a guide to the division-plate, 
C ; this division-plate has a vertical reciprocating motion, 
the course of which is regulated by the screw, m, which 
slides freely into the collet, m, screwed against the frame, A. 

This division-plate, designed separately in Fig. 7 and 8, 
is loosened towards the top for the passage of the cutting- 
file, h ; it is fastened flatwise in a circular form to regulate 
the position of a disc, n, also cut sloping at the top for the 
passage of the cutting-file ; this disc is furnished with two 
slides with screws, s, to vary its position, a crank-pin, o, y, 
is inserted at the centre, and a second pivot, p : y, is fixed 
near the circumference. 

A face-plate, g, pierced towards its circumference with as 
many holes as there are teeth in the escapement- wheel, is 
also pierced at its centre to receive the central crank pin, o, 
of the disc, n ; the holes towards the circumference alter- 
nately serve as a stop-work to the disc, n. 

This division-plate, q, receives the escapement- wheel, E, 
flatwise, whose semi-circular spaces it is to clear ; it is kept 
in its place by a coating of wax, and, in order to set it 


250 the watchmaker's manual. 

concentrically, it is adjusted on an axle in such a manner 
that it can turn quite round ; a little Spanish sealing-wax 
is placed on the divider, q, which is fixed against the wheel, 
and the whole is put on the lathe. The division-plate, q, 
is gently warmed to melt the wax, it is turned with the 
drill-bow, and then, by lightly resting a piece of wood 
against the divider, it is easily placed concentric to the 
escapement- wheel, R, and on the side of the teeth. 

The plate and the wheel, united in this state in a single 
piece, are removed from the arbor which passes through 
them, and the divider is adj usted on the space-column tool ; 
for this, the centre of the escapement-wheel is placed on the 
central pivot, o, of the disc, n, while the hole of the divider, 
q, which will cause the clearing at the necessary point, is 
placed beneath the crank-pin, p ; the placing is regulated in 
other respects by the relative change of position of the disc, 
?i, by means of two screws, s. 

The escapement- wheel is thus placed beneath the cutting- 
file and ready to be cleared of an entire tooth, and of about 
two thirds of the following one, only preserving a strength 
sufficient for the column ; for this, the axle of the cutting-file 
is worked by means of the drill-bow ; and the division-plate, 
C, furnished with the escapement-wheel, is then pressed 
upward in proportion to the working of the cutting-file. 

The operation of the space-column tool should be preceded 
by the previous division of the escapement or cylinder- 
wheel ; the number of teeth which must be arranged on this 
wheel is calculated to make it beat about fifteen thousand 

The same tool is Used to round the column beneath the 
inclined-plane by removing the division-plate, C ; the wheel, 
which is still joined to the division-plate, #, is placed against 
the piece B, the position of which is regulated by the 
adjusting-screw, &, and the screw-nut, j ; the cutting-file is 


then turned, which successively rounds the bottom of each 
inclined-plane in proportion as the wheel, R, is displaced by 
the other hand, in order to present all the teeth alternately. 
This operation is very easy ; it is only necessary to 
remark that the wheel, R, rests against the plate, q, opposite 
to that which is indicated by the design. 

Inclined- Plane Tool. 

This tool is also designed on a large scale. 

Figs. 19, 20 show the elevation and plane. 

A', the fixed part of the tool which is placed in the jaws 
of the vise. Two puppets, B, B, are fixed on this piece, A, 
by a common screw, each traversed by a distinct turning- 
tool, c, c, these turning-tools slide with friction into the fixed 
sockets of the puppets, and the screws, a' a', retain them in 
the proper position. 

A detent of tempered steel, D, pivoting upon a piece, 
£, sliding against the upright, A', can take any inclina- 
tion, which is given it by means of graduated parts ; the 
opposite extremity of this detent is terminated by a small 
handle, c, and is fixed into a movable notch adjusted 
against the upright, A, and retained at the desired height by 
the thumb-screw, d. The piece, Z>, is regulated to the suitable 
position by the adjusting-screw, e. 

The cylinder- wheel, R, mounted on its arbor, is placed 
between the two turning- tools, c, c' ; a spring, f, maintains 
the wheel, R, in its position by its pressure, by resting 
under one of its teeth, and all that part of the tooth which 
projects beyond the upper level of the detent, D, should be 
removed by the file. 

It is evident that, by the previous inclination given to 
this detent, if the wheel is successively turned, in order to 
cause it to present all its teeth to the slide, g, of the detent, 

252 THE watchmaker's manual. 

D, the inclined plane of the teeth of the escapement-wheel 
will be filed in a regular manner; 

The length of all the teeth of the wheel can also be 
equalized, as seen in Fig. 21 ; a slide, j\ whose position is 
regulated by the adjusting-screw, Z, is surmounted by a piece 
of tempered steel, m, in the form of a fork, in order to receive 
the steel spring, p, which is maintained at the interior by the 
small screw, n ; the position of this spring is such that, in 
placing the wheel between the two turning-tools, c, c', the foot 
of the tooth rests on this spring-band, while the top of the 
tooth is level with, or exceeds the upper level of the piece, m. 

By turning the wheel by the hand, the shortest tooth is 
found, the position of the spring is regulated with respect to 
this tooth, which is placed on a level with the first, and by 
this method an equal length is secured to all the teeth. 

The screw, r, holds the slide, j] immovable when its 
position has been determined by the adjusting-screw, I. 

The working parts of these tools are movable, and are 
regulated according to the diameters and the number of 
teeth of the wheels. 

Patent of M. Merle for a Movement of Clockwork. 

The improvements of M. Merle relate to the adjustment 
of anchor-escapements on their rod, and to the barrel of the 

The part which concerns the adjustment of anchor- 
escapements, says the inventor, is designed to remedy the 
inconveniences of the systems which necessitate the bending 
of the conducting fork of the balance, and of those which 
require the use of a heavier balance than usual. 

It consists in the idea of adjusting the anchor on its rod, 
in such a manner as to be able to cause the rod to turn in 
the hole of the anchor to a required degree, in order to give 
the necessary inclination to the fork without being obliged 


to bend or to twist it, and of checking it in its position by a 
thumb-screw, still preserving to the anchor the possibility 
of a slight friction on its rod. 

The anchor, instead of being fixed on a square, is adjusted 
on a round rod, in which a circular notch is made to receive 
the extremity of a screw designed to maintain the anchor on 
its rod, or rather the rod in the required position so as to 
guide the fork fixed at the other extremity of the rod to the 
right and left. 

It is evident that, when the movement of the balance is 
to be regulated, it will not be necessary either to bend the 
fork to the right or left, or to raise the pendulum from one 
side to the other; it will suffice to loosen the screw in order 
to permit the rod to turn, and thence to direct the fork, and 
consequently the balance, a little more to the right or left. 
The slight friction permitted the anchor on its rod, is 
designed to facilitate the connexion of the anchor with the 
escapement- wheel. 

The improvement made in the barrel consists in the idea 
of adding to it a second set of cogs, in order to simplify the 
striking-movement. In fact, by this second set of cogs, the 
necessity of employing two barrels is obviated ; that is, one 
for the striking-work and one for the movement, since one 
of these two sets of cogs, which the single barrel will carry, 
will correspond to the trains of the striking- work, and the 
other to the trains of the movement ; and the striking- work 
and the movement cannot stop without each other, as the 
winding of the barrel will serve for both by reason of the joint 
action on the two trains by a single agent. 

Patent of M. Allier, for Clocks running Six Months and a 
Year without being wound up. 

"As my method," says M. Allier, "is applicable to all 

254 the watchmaker's manual. 

kinds of clockwork, I use every kind of striking-work 
without distinction. 

" I suppress the other movements, the barrel-movement, 
the time-wheel, and the pinion of the centre-wheel ; only 
preserving the centre- wheel, the third wheel, and the escape- 

" My centre- wheel is supported by a bridge at the interior 
of the large pillar-plate ; the arbor, which passes through 
the wheel, carries a steel arm which is adjusted above. 

" In front of the pivot of the centre-wheel, I place a small 
barrel surmounted by an arm which seizes that of the 
centre-wheel. The arbor of my small barrel is a pinion 
which is carried, outside the large pillar-plate, by a wheel 
adjusted with friction by the rod of the striking- wheel, 
between the pillar-plate and the notch- wheel ; it is sustained 
by a spring so as to permit the clock to strike to set it at the 

" The pressure-spring, which is placed between the notch- 
wheel, and the auxiliary-wheel, gives to this wheel the 
power of winding the small spring, in order to make the 
clock go. 

" By a certain process, I suppress the pressure-spring and 
make a slide-spring which is adjusted in my little barrel, 
which, when the small spring is all banded above, lets 
the striking- work go and slides with friction into my 
small barrel. The arbor-pinion of my small barrel is 
sustained outside the small pillar-plate by a bridge; its 
other pivot rolls in the steel ferrule which is adjusted to 
the pivot of the centre-wheel, and which holds the arm of 
this same wheel. 

" The clock is wound continually from half-hour to half- 
hour, as the small spring constantly draws uniformly on 
the trains of the movement and gives a constant force. 

" I make my clocks go by a similar process ; instead of 


placing my small barrel- movement independent of the 
centre-wheel, I fix it on a rod and it serves as a wheel as I 
make a set of cogs equal to that of the centre- wheel ; I pierce 
my pinion, which forms an arbor and works with the wheel 
which winds the small spring, which is held by a slide so 
as to permit the clock to strike. 


"I place in a barrel-remontoir, to which I give the force 
and the number of teeth necessary to keep the spring of 
the striking-work wound, which also winds the small spring 
of the movement, as may be seen from the previous de- 
scriptions ; I cause the large barrel-remontoir to work with 
a wheel which I substitute for the ratchet-wheel of the strik- 
ing work barrel, which is adjusted on the arbor of the same 
barrel, and which keeps it wound during the time required 
for the clock to run, whether a year, thirteen, or fourteen 
months: I usually fix on a year because it is a certain 
period, which always preserves constant force. 

" On the same principle of constant force, I make watches 
with no more motive-power than that of twenty -four hours, 
with but five wheels, which run for a month and several 
days; these are as well regulated as the most accurate 
marine chronometers. 

" My escapement-wheel is more highly numbered than 
others ; I place a time- wheel before the centre- wheel, and 
adjust a small barrel to the centre-wheel as in my clocks, 
and thus obtain the time with perfect regularity. 

Patent for Addition and Improvement 

" The change which I have made consists in the suppres- 
sion of the auxiliary- wheel which is between the notch- 
wheel and the small pillar-plate ; when this is done, the 

256 the watchmaker's manual. 

great-wheel works with two pinions which simplifies the 
work and gives more force to the escapement. 

"Besides, I remarked that the suspension with a silken 
thread was subject to the hygrometrical variations of the 
atmospheric air ; to remedy these variations, I propose to 
use a metallic suspension which can be easily regulated by 
a knob which is turned to the right or left, to put an 
eccentric piece in motion which will communicate the 
movement to the balance by means of a lever, to lengthen 
or shorten it. 

"The wheel of the striking-barrel acts upon the pinion 
of the striking-wheel ; the striking-wheel acts upon the 
pinion of the pin-wheel. 

"In the first arrangement, the arbor of the striking-wheel 
carried, at the extremity of the back pillar-plate, an auxiliary 
wheel which acted upon the pinion of the small barrel. 

"In the last arrangement, the striking-wheel acts upon 
the pinion of the pin-wheel and also with that of the small 
barrel, which gives greater force and regularity as this is 
effected by a first-mover. 

" The small barrel of the centre is surmounted by a 
finger which connects itself with another, fixed on the rod 
of the centre-wheel. 

" The spring of the small barrel is grappled by a slide- 
spring, moving with friction into the small barrel. The 
other gearings of this mechanism are the same as those 
described in the first patent." 

Patent of M. Jacot for a Movement of Clock-work. 

"The numerous inconveniences which the vibratory 
movement of the pendulum presents," says M. Jacot, 
" whether by the dilatation or contraction of the metals, 
which is caused by the changes of temperature, or by the 


constant percussion which takes place in order to effect 
this movement, have induced me to seek a surer method by 
which to avoid these difficulties. 

" The action of the spring or motive- weight in watches or 
clocks, is checked momentarily by the shock which each 
oscillation of the balance produces ; this results in a sensible 
deterioration of the whole machine, and especially in those 
parts most exposed to the immediate contact with the shock. 

" This invention does not change the gearings, the motion 
of the hands, or the ordinary movement, but instead of the 
spiral-springs of watches or the pendulums of clocks, it 
employs an eccentric piece, whose movements are relative 
to the velocity of the balance, which turns constantly in the 
same direction, moved by the alternate force of the eccentric 

" This rotary movement of the balance is governed by 
the centrifugal force which, acting at the extremity, opposes 
a resistance at the centre, regulated by a spring whose 
pressure is increased or diminished by means of screws, in 
order to obtain a fixed number of revolutions in a given 

" This mechanism is composed of a barrel of eighty teeth ; 
a centre-wheel of sixty teeth, and pinion of ten leaves; 
a third- wheel of sixty teeth, and pinion of six leaves ; a 
second- wheel of sixty teeth, and pinion of ten leaves ; and 
a fourth wheel of sixty teeth, and pinion of ten leaves. 

" This last wheel acts upon a pinion of twelve leaves 
which impels the eccentric bar and causes it to describe an 

" This bar, being pivoted loosely at each end, produces 
an alternate movement, and communicates a rotary move- 
ment to another wheel of one hundred and eighty teeth, 
which works into a pinion of six leaves, fixed on the 

258 the watchmaker's manual. 

" This balance is a steel bar, cleft at one of its extremities, 
and pierced to receive a lever ; this lever carries a metal 
weight at one side. The centrifugal force compels the 
weight of the lever to throw itself outside when the balance 
has acquired a certain velocity, and the other extremity 
effects a friction against a cjdindrical piece of steel, or any 
other metal, fixed to the pillar-plate, and having the arbor 
of the balance for its centre. 

" A small spring is fixed by a screw on the same side 
of the balance and on the bar itself, which serves to 
regulate the effect of the centrifugal force in acting on the 

" A steel piece, carrying a weight designed to establish 
the equilibrium, is fixed by a screw to the opposite extremity 
of the balance. 

" The impulse being given to the whole series of the 
train by the weight or spring, will continue to increase the 
velocity until the friction opposes a resistance equal to the 
action of this weight or spring. By placing the eccentric 
piece at the end of the rotary movement of the train, it 
becomes itself an alternate movement, and thus produces a 
fall at each end of the ellipsis which it is forced to describe, 
acting in some sort like the balance of a clock every time 
that the pallet comes in contact with the rencounter- wheel ; 
but this fall is not left to itself but is raised up again by 
the balance; each oscillation equalizes the movement, and 
the shock becomes almost insensible on the pinion of the 

"The eccentric piece both governs the balance and is 
itself governed by it ; and the balance is governed by the 
centrifugal force, for, the number of turns being fixed, it 
cannot increase without finding a proportional resistance, 
and cannot possibly diminish as long as the .spring or 
weight acts on the gearings." 


Patent of M. Rabinel for an improved Watch. 

By this new pillar-plate, extra flat watches are obtained 
which have more force than the ordinary Breguet pillar- 
plate watches ; the click and spring- work of these watches 
is enclosed in the shell of the barrel. The barrel is held by 
a steel-bridge of the thickness of the hour- wheel, this bridge 
is placed beneath the dial. 

The bridge which carries the barrel, and on which the 
click and spring- work is placed in ordinary watches, is not 
found in this ; that of the centre-wheel, which is no longer 
at the centre, is, with the others, on a level with the barrel. 
The barrel determines the depth of the watch. 

The motive-force is communicated to the centre-wheel 
by two pinions placed on the pillar-plate, between this wheel 
and the barrel. 

The bridge on which the centre-wheel turns holds 
these two pinions in a frame when the depth of the watch 
permits; when this is not the case it is suppressed and 
replaced by the small bridge which only holds the pinion 
of the centre ; the other, which we shall call the pinion- 
wheel, is held by a screw, which is screwed into a steel-stud 
riv t?d in the pillar-plate; the head of this screw does not 
extend beyond the pinion- wheel ; this wheel is of steel. 

The arbor for setting the hour is at the centre. 

ISTo change is made in the number of the wheels, although 
there are two more pinions ; that of the centre carries ten 
teeth, and the pinion- wheel thirty ; the number of the latter 
is unimportant. 

Patent for Addition and Improvement. 
In certain watches in which the inventor has not thought 

260 the watchmaker's manual. 

it advisable to put his click and spring-work arbor, he has 
replaced it by the Breguet arbor modified, using the same 
barrel-system of the ordinary flat watches. 

This improvement only relates to the barrel-arbor ; it 
permits the use of higher springs, and a longer winding-up 
arbor than in the common flat watches. 

The octagon of the arbor enters into that of the ratchet- 
wheel ; these two pieces thus jointed and riveted forming 
but a single piece. 



The art of cleaning and repairing watches demands as 
much care as that of making them, and the workman who 
cannot execute a new watch will certainly be incapable of 
mending one well that is broken or worn. We shall not 
attempt to describe here the art of repairing, which would 
demand several volumes in itself, and we should not then 
be certain of including every case which might be presented. 

Crespe, of Geneva, has devoted a 12mo. volume of three 
hundred pages to a single kind of repeating- watch, with- 
out describing all the difficulties which may be encoun- 
tered in it. Volumes on volumes would be required to treat 
of all the pieces of clockwork with the same details. "We 
can therefore only speak here of generalities. 

With this view, we advise the repairer of watches to 
examine each piece of the machine with scrupulous care, to 
assure himself that the teeth of the wheels and the pinions 
are precisely alike and perfectly rounded, that the pivots 
are cylindrical and well polished, and that their ends do not 
rub upon the plate, that the holes are not too large and have 
not become oval ; that the escapement, whatever it may be, 
is well made, that the wheels have sufficient play to avoid 
friction ; that the balance turns horizontally and does not 
rub on any piece ; that the spiral-spring is flat and is turned 
in such a manner that the coils do not rub on each other, or 
on the pillar-plate or balance ; that the gearings are good, 

262 the watchmaker's manual. 

etc., etc. In all these cases, as well as in those which we 
have not mentioned, the defects should be remedied, and 
the machine rendered as perfect as though it had just been 
made, this will insure its regularity. 

The cleaning of clocks and watches is more difficult and 
demands more minute care than ordinary workmen imagine. 
They often rub the pieces with a brush and Spanish white, 
and remove the gilding in a short time. The whiting which 
they use fills the teeth and the leaves of the pinions, and 
they are not always careful to remove it, so that the watch 
is often dirtier when they have finished than when it was 
brought to them. Care in respect to the details we have 
mentioned, added to a thorough knowledge of the construc- 
tion of the watch, will insure success in this art to the 


The time that elapses between the departure of the sun 
from and its return to a meridian, is called by astronomers 
the natural or solar day. These days are not uniformly 
twenty-four hours in length, as the movement of the sun is 
variable, consuming a few seconds more or less each day in 
its departure from and return to the meridian. For this 
reason, astronomers have suppposed fictitious days of equal 
length, which they call mean time ; this is that which is 
indicated by clocks. The time measured by the meridian, 
that is, by the noon of the sun, is called true time, and the 
difference that occurs daily between the noon of the sun 
and the noon of the clock, that is, between the true time 
and the mean time, is called the equation of time. To mark 
this variation, equation tables are arranged which indicate 
the precise difference between the true and the mean time 


each day in the year, and serve as a guide in the regulation 
of clocks and watches. 


The longer a pendulum is, the slower are its vibrations, 
and, on the contrary, the shorter it is, the faster are its 
vibrations ; it is, therefore, necessary to lengthen the pen- 
dulum to make the clock run slower, and to shorten it to 
make it run faster ; this is done by means of the screw nut 
underneath the pendulum ball, or if this is inaccessible 
through the form of the case, by turning an arbor in the 
dial with a key, or by other constructions which produce 
the same effect. 

The hands of a clock should never be turned backwards 
more than half an hour, and even this should be done with 
care, stopping at once in case of resistance. The minute 
hand should never be turned backward when the clock is 
on the point of striking ; as, in this case, the clock will 
strike at the moment of turning the hand, then strike again 
when the hand has reached the same place on the dial to 
which it was turned, thus causing a discord between the 
striking-work and the hour. When this occurs, the minute 
hand should be turned forward till it is within about two 
minutes of the hour, then turned backward till the clock 
strikes, then again turned forward till it strikes a second 
time, which will put the hands in accord with the hour. 

When the striking work of a clock is not in accord with 
the hands, that is, when it strikes one at twelve, the hour- 
hand should be turned separately till the right hour is 
struck, when the minute-hand should be turned to its place 
on the dial. 

Clocks are regulated to mean time, either by a regulating 

261 the watchmaker's manual. 

clock, or by the passage of the sun in the meridian. For the 
latter, the variation of the true from the mean time is found 
from the equation tables ; then, supposing, for example, that 
on the 6th of October the sun is twelve minutes in advance, 
at the instant that the sun passes the meridian, the clock is 
set at twelve minutes before noon. It is then tested daily 
by comparisons made in the same manner, by the aid of 
the equation tables, and the regulation made in accord- 
ance with the variation, until a uniformity of movement is 
attained. Equation clocks are constructed, which follow 
the variations of the sun by the aid of machinery arranged 
for that effect. 

In setting up a clock, great care should be taken that it 
should be exactly perpendicular, and firmly secured in its 
place, so as to prevent all possibility of jarring, as the regu- 
larity of its vibrations, and consequently, its accuracy, de- 
pend on this in a great degree. 

When a watch is not regulated, it is commonly said that 
it varies, yet there is a great difference between a watch 
that is not regulated and one that varies ; for a watch may 
be perfectly constructed and run regularly, yet not be regu- 
lated to the mean time, as may be seen by comparing it 
with a regulating clock, from which it will deviate in a 
uniform ratio from day to day ; while one that varies 
from this irregularly, being sometimes faster and sometimes 
slower, is, on the contrary, a watch that varies. When 
these variations amount to several minutes in the course of 
the day, the regulator will have little effect on them, as the 
evil lies in the mechanism itself, and can only be remedied 
by the hand of a watch-maker. 

To judge of the accuracy of a watch, it must be set by a 
regulating clock, and left to run for twenty -four hours in 
the same position, noting at intervals of six hours, or there- 
abouts, the variations it has made from the clock. If it 


loses or gains time at a uniform rate, say one minute in 
every six hours, it is a proof that the mainspring acts 
uniformly upon the train, and the latter in turn upon the 
balance. After the watch has been thus tested for several 
days, it is worn for a time, and the variations noted as 
before ; if these continue in the same ratio, it is a proof that 
the watch runs well, and tjaat to regulate it, it is only neces- 
sary to have recourse to the regulator, which is turned 
forward or backward, according as the watch is required to 
go faster or slower. The distance which this must be turned 
varies in different watches, and can only be determined by 
actual test. 

But if the watch, after having varied four minutes in 
twenty -four hours while suspended in one position, varies 
more or less than this when worn, it is evident that it varies 
from some defect in the mechanism, and can only be cor- 
rected by the skill of a watchmaker. 

To set a watch to the hour, the arbor of the minute-hand 
is turned with the key till the watch indicates the correct 
hour and minute, care being taken to turn the hour and 
minute-hands together. 

When the repeater indicates one hour and repeats 

another, the hour-hand is turned separately to the hour 

and quarter which has been repeated ; if this turns easily, 

it may be concluded that it has been put out of place acci- 

| dentally ; this having been done, both minute and hour- 

! hands are turned to their places on the dial. But if the 

j hour-hand turns with difficulty, the derangement of the 

hands and the repeating has been caused by the pieces 

beneath the dial, and requires the aid of a watchmaker. 

When the hands of a watch are in advance of or behind 
the hour, they must be turned to their place by the nearest 
way, whether forward or backward ; there is no more harm 
in the one than the other. Many persons, who have let 


266 the watchmaker's manual. 

their watches run down, in the fear of spoiling them, turn 
them forward eleven hours rather than backward one ; but 
in this manner they do precisely what they seek to avoid, 
as in turning the hands so frequently, they loosen the canon- 
pinions which carry them, so that the least thing deranges 
them, and the watch runs while the hands remain stationary. 
When a striking, alarm, or any other watch is in question, 
the mechanism of which involves risk in the retrograde 
movement of the hands, and the minute-hand does not turn 
backward with ease, both hands had better be turned for- 

The hands of a repeater should not be turned while the 
watch is striking. When it strikes too fast or too slow, the 
defect is corrected by turning a small regulator placed inside 
the watch by the side of the cock. 

The seconds-hands of watches should not be turned at all. 
To set these to their place, the balance is checked, until the 
seconds hand marks the correct time, when the hour and 
minute hands are set right, and the watch again set in motion. 

Many causes contribute to the variation of watches ; heat 
and cold in watches without compensations, of which many 
are in use; inequality of the force of the main-spring; 
friction, jarring, thickening of the oil, etc. In view of 
these, care should always be taken to wind the watch at the 
same hour; as many watches lose time during the first 
twelve hours after winding, and gain the same amount 
during the successive twelve, and vice versa, the loss of the 
first twelve hours is thus compensated by the gain of the 
last ; whilst, if the watch is suffered to run more than twenty- 
four hours, the gain will continue without compensation, 
and the watch be subjected to greater variation. 

The watch should be carried as nearly as possible in the 
same position. In the fob, for example, it is usually sus- 
pended by a chain ; when not worn, it should therefore 


be hung on a nail, taking care that the case may rest on 
the wall, so that the vibration of the balance may not be 
communicated to the watch. 

A watch without compensation should be kept as nearly 
as possible in the same temperature, and care should be 
taken not to lay it on marble, or similar conductors. 

A watch should be cleaned once in three years. 

Earnshaw's Detached Escapement. 

For the following description of the Earnshaw escape- 
ment, now in general use for pocket as well as marine 
chronometers, we are indebted to Mr. Keed's excellent 
Treatise on Clock and Watchmaking. 

The balance-wheel is plain, or flat, made of steel, and 
sometimes of brass, the teeth have somewhat of the ratchet 
form, and are considerably undercut on the face, the number 
of teeth being twelve, and calculated so as to give half 
seconds, by the step of the seconds hand on the seconds 
circles in the same way as is effected in Arnold's. The steel- 
roller or main-pallet has an opening on it, the face of which is 
also much undercut, having a piece of some fine stone, such 
as hard ruby or sapphire, set into it, for the purpose of 
making the points of the teeth work smoothly on it, and 
prevent any wearing from their constant action. A stud is 
fixed to the potence- plate, and to this stud a detent-spring 
is screwed, and made very slender and weak near the stud. 
It is by yielding at this place that any motion can be given 
to the detent on which the wheel is locked ; and here is its 
centre of motion. When acting, a tooth of the wheel 
becomes locked on a flat side of the stone-detent, which is 
fixed in the thick part of the detent-spring, by means of 
which it presses against the inside of the head of an adjust- 
ing-screw which works in a fixed stud, so that when it is 

268 the watchmaker's manual. 

screwed in this stud, the detent will have less hold of the 
tooth, and vice versa. A delicate spring, called the lifting- 
spring, is attached to the inner-side of the detent-spring. 
The end of the detent-spring is bent a very little, so that the 
free end of the lifting-spring may bear only on the inward 
bent point. Concentric with the main-pallet is the small 
lifting-pallet, which is flat on the face, or lifting-side, and 
tapered or rounded off on the opposite side. When the 
mechanism is in motion, this comes with its face against the 
lifting-spring, which it would carry away with it ; but this 
cannot take place without taking along with it the detent- 
spring, and consequently the detent is carried out from 
locking the tooth, D, of the wheel. By this time, the 
main-pallet has got so far forward as to be in the way of 
receiving impulse from the tooth, B, and before it can 
escape, the lifting-pallet parts with the end of the lifting- 
spring, and leaves the detent and detent-spring immediately 
to resume their place. The detent will be then ready to 
receive the teeth, C, by which the wheel is again locked. 
The balance, having performed the vibration by the impulse 
given, returns, and with it the lifting-pallet, the tapered side 
of which will press the lifting-spring inwards, but cannot 
carry the detent-spring with it, this being prevented by the 
inside part of the head of the adjusting-screw; after passing 
the lifting-spring, it goes along with the vibration of the 
balance, on whose return the face of it will again meet with 
the lifting-spring ; unlocking then takes place, and so on. 
The unlocking here is performed by carrying the detent 
outward from the centre of the wheel, which is locked by 
the extreme points of the teeth. Mr. Earnshaw gives as a 
rule for making the inclination of the faces of the teeth and 
main-pallet, that they should be in a line drawn from the 
points of the teeth, as a tangent to a circle whose diameter 
is half that of the wheel ; and the same rule is used for the 


face of the pallet. The detent-spring lies above, and clear 
of the wheel, and the detent stone-piece may be either a 
semi-cylinder or an angular-piece. A flat side is, however, 
in either case, requisite for the wheel to lock on it, and the 
height or length of this stone should be a little below the 
under side of the wheel, so that the teeth may at all times 
have a sure hold on it. The diameter of the roller or pallet 
is larger than that of Arnold's, which allows the teeth of the 
wheel to give a more direct impulse to it. The diameter 
of the roller, however, if carried too far, would lessen the 
hold of the teeth on the pallet. Where a wheel of twelve 
teeth is used, it will give scope for getting in a pallet of 
considerable length. The proportion between the diameter 
of the balance-wheel and roller seems to be the same, or 
nearly the same, in Arnold's and Earnshaw's escapements. 



To complete this Manual for the use of American 
artisans, it only remains for us to give a brief history of the 
rise and progress of clock and watchmaking in America. 

At the beginning of the nineteenth century, the art of 
horology was unknown on this side the Atlantic, and though 
clocks and watches were imported to a considerable extent, 
the number then in use was small, indeed, in comparison 
with the present multiplicity of time-keepers. In some of 
the more pretentious dwellings might have been seen the 
heavily-cased English clock, the bizarre time-pieces of 
French and Swiss manufacture, and the German clock 
with its uncased dial and long swinging pendulum, yet a 
large proportion of the population eschewed these luxuries 
as beyond their means, and contented themselves with mark- 
ing the lapse of time by the hour-glass, the noon-mark, or 
the sun-dial. It was reserved for the ingenuity of American 
mechanics to devise the means of manufacturing these useful 
machines so cheaply as to place them within the reach of 
the million, and, at the same time, with precision enough to 
render them available for all practical purposes. 

Perfect as may be the theory of European clock and 


watchmaking, its practice has always been marked by a 
strange want of system. The different parts that go to 
make up these useful machines are manufactured in dif- 
ferent places by different workmen, then sent to other 
localities for adjustment and finishing, and, though with 
sufficient time and pains, these may be and are executed by 
skilful artisans with marvellous accuracy, it is obvious that 
this pains can only be bestowed upon a few costly time- 
pieces, while the majority will be liable to be more or less 
defective. The American mechanics have obtained the 
advantage of systematizing their work by manufacturing 
all the pieces in one establishment under the supervision of 
a single workman, then duplicating them rapidly by means 
of machinery. By this labor-saving process, they attain both 
cheapness and accuracy, since work executed by well con- 
structed machines must be more uniformly perfect than that 
which is made by handicraft, whilst the rapidity of the pro- 
cess of multiplication is so great that the cost of manufacture 
must be almost nominal in comparison with that of the 
latter. This advantage, which has lately been obtained in 
the manufacture of watches, has for many years secured to 
the mass of American clocks a world-wide reputation for 
their cheapness and accuracy. 

About the year 1800, Eli Terry of Plymouth Hollow, 
Connecticut, first commenced the manufacture of the famed 
American clocks, which now form so large a part of our 
exportations. This was on a small scale enough at first ; 
after manufacturing two or three clocks, he would sling 
them on his saddle and traverse the country till he had 
disposed of them to advantage, then return and resume his 
work. The movements of these earliest clocks were of 
wood, of a construction similar to the common English 
clocks ; the introduction of sheet brass was of later date. 
Ere long, the "wooden clocks" gained popularity by their 



convenience and cheapness, the manufacture was extended 
by the original projector; other manufacturing establish- 
ments were founded, and by degrees Connecticut and a part 
of Massachusetts became the seats of a flourishing clock- 
making business. Machinery was applied to the manu- 
facture, the wheels, instead of being cast separately as in the 
old method, a process of infinite delicacy and precision, 
were rapidly cut from sheet brass by this labor-saving 
device, the pivots were made of inexpensive iron-wire and 
the whole adjusted in the same establishments, thus affording 
facilities for cheapness combined with uniformity of execu° 
tion superior to those of any method hitherto pursued. The 
sheet-brass used in the manufacture of these movements also 
possesses many advantages over the cast brass, being finer, 
more easily wrought, and free from the inequalities so often 
caused by the hammer of the workman. 

Eli Terry, the father of the enterprise, continued in the 
business until his death a few years since, after which the 
manufacture was for some time conducted by his sons 
under the name of the Terry Manufacturing Company, now 
become extinct. Next in the ranks came Seth Thomas, 
of Plymouth Hollow, who died in the beginning of the 
present year, and whose manufacturing establishment, still 
conducted under his name, is the oldest now in existence. 

The clockmaking business, though carried on to some 
extent in New York, Massachusetts, and Maine, still remains 
principally confined to Connecticut. The following list of 
the principal manufactories of the state, with the approxi- 
mate number of clocks of their manufacture, will give some 
idea of the extent of the business at the present time. 

New Haven Co., New Haven . . . 150,000 

Elisha Welch Co., Bristol 100,000 

Seth Thomas Co., Plymouth Hollow . 75^000 

Waterbury Co., Waterbury . . . 50 ? 000 


Gilbert Co, Winsted .... 40000 

Ansonia Brass and Clock Co, Ansoma -W,uuu 

Pomeroy & Parker, Bristol -W,UUU 

Maurepas, Bristol 5,000 

The census of the state of New York, for 1855, gives the 
following statistics of clock manufacture : 

Manufactured Persons 
Number of factories. Capital invested. Eaw material, articles, employ- 

Eeal estate. Tools and material. 

Madison Co. . ftl A ,. 

Cazenovia, 2 3,200 2,200 1,100 4,610 5 

N N Y ew C Tork, 5 51,000 9,100 64,000 163,000 87 

"^,2 4,500 5,000 4,375 11,000 12 

Tompkins Co. ^ 

Tthara 1 500 

I,rn ' u 1 15,000 

Williamsburg, 1 

Besides these, there are five chronometer manufactories in 
New York, with a capital of about $17,000, employing 

forty-nine men. " . 

These clocks form an important item m our exportation 
Lar^e numbers are annually exported to Europe and South 
America, and the demand even reaches as far as China and 
Japan. The price usually varies from one to ten dollars, a 
fair average price being two dollars and a half. A lew 
higher-priced clocks and regulators, worth from two to three 
hundred dollars, are also manufactured in these establish- 
ments- but these are more usually supplied from Europe, 
the demand not being great enough to warrant the outlay 
necessary to produce that exquisite accuracy in time-keepers, 
which is required in comparatively few conditions. 1ms 
matters little, as these specialties in the art can be imported 
from tbose countries where labor is cheap, at a less cost 
than they could be manufactured here. Most of these come 




from England and Switzerland. As a master-piece in time- 
keeping machinery we may mention a turret-clock that has 
fallen under our notice, made by Thomas Levland of 
Prescot, England, and imported by Messrs. Tiffany and Co 
of New York, as a regulator in their establishment, the 
greatest variation of which, as tested by a transit instrument 
under the charge of Prof. Bull of the New York University 
has not exceeded nine seconds within the last ten months' 
This movement, compensated by means of a mercurial pen- 
dulum with a steel rod and glass bulb, and cased in a heavy 
carved rosewood frame of admirable workmanship, firmly 
secured to the wall by marble brackets, so as to obviate all 
possibility of external disturbance, affords a fine illustration 
in its perfection of the triumph of horologic science. 

Although these fine timekeepers are not usually exe- 
cuted in the large manufacturing establishments, there are 
several artisans in America who have made their manufac- 
ture a specialty, and whose work will compare favorably 
with the most celebrated European clockmakers. Chro- 
nometer-making has received special attention from these, 
and the American marine chronometers are acknowledged 
as equal to any in the world. 

The following statistical table, compiled from the last 
census (1850), will give some idea of the present state of 
clock-making in America : — 


in 1850. 


New Hampshire, 

Vermont, . 


Rhode Island, 


Connecticut, ' . 

. 837 


New York, 

. 173 


New Jersey, 

. 15 



. 105 


Delaware, . 




Maryland, . 
District of Columbia, 
North Carolina, 
South Carolina, 
Alabama, . 
Mississippi, . 
Louisiana, . 
Texas, . 






Ohio, . 





Iowa, . 













Although the same or even greater advantages must 
accrue from the duplication by machinery of the parts of 
watches as of clocks, no attempt has been made till within 
a few years past to adapt this process to the manufacture 
of these machines. "While we have supplied the world 
with American clocks, we have continued to import 
watches from England, France, Switzerland, and Germany, 
at a cost of over five millions dollars per annum, while 
the annual cost of repairing has amounted to as much 
more The value of the watches imported into the United 
States from 1825 to 1858, inclusive, as shown by the pub- 
lished returns of the Treasury department, is $45,820 00U, 
almost equally divided between England and Switzerland, 
at present the great European depots of the watch-trade ; 
while the number of watches supplied by the latter is 
almost three times as great as that of the former owing to 
the lower price and less substantial character of their work- 
manship. Coventry and Prescot in Lancashire and War- 
wickshire, England, and Locle and Chaux-de-Fonds m the 
northern Cantons of Switzerland, near Geneva, are known 
as the great central emporiums of watch manufacture. 
Denmark too, through the watches of Jurgensen has 
recently acquired a reputation in the art. It is but just, 


however, to say, that the greater part of the movements of 
all are made in Switzerland, where whole cantons are en- 
gaged exclusively in the manufacture, one hamlet taking 
one piece of the watch as its specialty, and another others. 
These pieces, after being cast, turned, and drilled, are sent 
to the finishers at London or Paris, where they are adjusted, 
cased, and set in motion. From this process it results that 
each watch will necessarily have a distinctive character of 
its own, and that it is only by the merest accident that the 
movements of two watches can be found in exact corre- 
spondence, or that a piece once broken can be replaced by 
another precisely like the first. From this want of system 
then, and not from any deficiency in theory, arises the im- 
perfections that are so annoying in the mass of imported 
watches. This fault, remedied with such success in the 
manufacture of American clocks, is now receiving the 
attention of American watchmakers, and, though the experi- 
ment has but just been commenced, it is safe to predict that 
it will prove a success, and that the time is not far distant 
when American watches will form as valuable an article in 
our commerce as have the American Clocks. Meanwhile, 
while availing themselves of the advantages of the iron 
fingers of machinery, our artisans will do well to study and 
improve upon the ingenious theories of European horolo- 
gists, in order to bring these delicate machines to that per- 
fection of which they are susceptible. 

Although it is only within a few years that the manufac- 
ture of watches has crystallized into a substantial form in 
this country, they have been made by individuals from 
time to time since the period of the first introduction of 
clocks. During the war of 1812, good watches were made 
by Groddard and others in Worcester, Massachusetts, 
some of which are still in existence ; but after the close 
of the war, the importation of watches was resumed, 


and the home manufacture failed for want of capital and 

In 1830, Henry Pitkin, of East Hartford, Connecticut, 
made an attempt to revive the enterprise, and manufactured 
about a thousand watches there and in Boston, but, not 
meeting sufficient encouragement, he at length relinquished 
the undertaking. Other spasmodic efforts at the manufac- 
ture of watches were made from time to time, but all proved 
unsuccessful; and, though watchmaking still remained a 
distinct profession, the watchmakers became a sort of inge- 
nious factotums, whose business it was to repair watches 
of foreign manufacture in addition to clocks, jewelry, and 
silverware, and not unfrequently locks, guns, etc. 

It was not until 1850, that A. L. Dennison of Brunswick, 
Maine, an ingenious mechanic and practical watchmaker, 
first suggested the idea of systematizing the manufacture 
of watches by making and adjusting the whole movement 
in a single establishment, and duplicating the pieces by a 
connected system of machinery, thus securing, not only a 
great economy of time, but also an exact correspondence 
in the parts of an infinite number of watches. Under the 
direction of Mr. Dennison and others a company was 
formed, under the name of the Warren Manufacturing 
Company, subsequently known as the Boston Watch Com- 
pany, and a manufactory was established at Eoxbury, 
Mass. ; but this locality was soon found unsuitable, as, the 
soil being light and dry, and the place one of the leading 
thoroughfares to Boston, the clouds of dust that were raised 
in consequence interfered with the operations of the work- 
men, and materially injured the delicate mechanism. The 
establishment was accordingly removed to Waltham, Mass., 
where extensive buildings were erected on the banks of 
the Charles Biver, and the manufacture continued until 
1857, when the original company failed, and the establish- 


ment and business passed into the hands of Royal E. Rob- 
bins and associates, who, uniting with the Waltham Im- 
provement Company, were incorporated during the 
winter of 1858-59, under the name of the American 
Watch Company, with a landed property of over one hun- 
dred acres, upon which it was proposed to erect houses for 
the artisans employed in the establishment, of which Mr. 
Dennison, the original projector of the enterprise, still re- 
tained the superintendence. 

Since this time, the American Watch Company has 
extended its operations, until more than two hundred arti- 
sans, men and women, are constantly employed, producing 
twelve thousand watches per annum, varying from the 
simplest form of the lever movement to the adjusted chro- 
nometer balance. These movements are of one uniform 
size, measuring one and thirteen-sixteenth inches across the 
dial, and are constructed after the English fashion, with a 
two-plate frame opening at the back, with dome-cap at- 
tached to the case. The English patent lever escapement 
is used, wisely modified after the Swiss method, by the 
omission of the main- wheel, fusee, and chain ; the power 
being communicated direct from the barrel to the train. 
This suppression of the fusee has long been advocated by 
the French theorists as securing greater simplicity, less 
friction in the transmission of the motive power, the use of 
a lighter spring which is surer and more uniform in its 
action, and more room for play in the frame for the other 
parts of the movement; and this construction, so vigor- 
ously defended by them, is now beginning to be accepted 
by the English horologists themselves, and is adopted in 
the system of the American manufacture. 

The chief distinctive feature in this system is the dupli- 
cation of every part of the watch by machinery, so that 
every movement is the exact counterpart of every other. 


These, with the exception of the jewels and the pivots that 
run in them, are cast by machinery, adjusted to a certain 
gauge, and so delicate as to mould tiny steel screws in its 
grasp, 100,000 of which are required to make a pound. 
The jewels are drilled with a diamond, and opened with 
diamond dust on a soft iron wire. The pivots that are to 
run in these are turned and polished, then tested by a gauge 
adjusted to the ten-thousandth part of an inch, and fitted 
to a jewel drilled one degree larger in order to afford the 
pivot sufficient play. Both jewels and pivots are carefully 
classified, and the sizes used in each watch recorded under 
its number, so that any that may be broken can be easily 
replaced. A steam-engine of twelve-horse power forms 
the pulse of the whole establishment, giving motion to a 
net-work of shafting that traverses the building. By this 
process, a far more extensive adaptation of machinery to the 
manufacture of watches than has hitherto been made has 
been successfully effected — four-fifths of the whole work 
being done by machinery, while but one-fifth is thus made 
in the European establishments — and manifold advantages 
are secured in the uniformity of the movement of the time- 
pieces, as well as in the facilities for repairing them when 
broken or out of order. The watches thus manufactured 
have proved themselves good time-keepers, and the cheap- 
ness of their execution affords earnest that they will follow 
in the wake of the American clocks in their journey over 
the world. 

We subjoin the following statistics of watchmakers in 
America from the last census (1850), premising that the 
number has increased largely since the enumeration. 




IN 1850. 

Maine, . 

. 45 

Louisiana, . 

New Hampshire, . 

. 37 



. 10 

Arkansas, . 


. 213 

Tennessee, . 

Rhode Island, 

. 41 

Kentucky, . 


. 28 

Ohio, . 

New York, 

. 708 


New Jersey, 

. 122 



. 712 


Delaware, . 

. 3 


Maryland, . 

. 93 

Iowa, . 

District of Columbia, . 

. 14 

Wisconsin, . 


. 69 

California, . 

North Carolina, . 

. 17 

Minnesota, . 

South Carolina, . 

. 36 

New Mexico, 


. 31 



. 6 

Utah, . 


. 14 

Mississippi, . 

. 26 






















Alarm. — A simple and ingenious machine adjusted to the clock, by 
means of which a hammer strikes upon a bell at a given hour or moment 
of the night, making a noise sufficiently loud to awaken a sleeper. 

Anchor. — Piece of the escapement, used in clocks and lever watches. 

Arbor, axle, rod, or axis. — Synonymous terms for the designation 
of a piece which turns upon itself by means of its pivots. 


Balance. — The balance is a bar, balanced by two weights, or a 
circular ring, with a rim concentric to an axle carrying two pivots, 
upon which the ring can turn freely ; it therefore remains in equili- 
brium with itself by its nature, whatever may be its position, and 
should keep up a uniform movement in whatever position may be 
given it. The balance, joined to the first known escapement — that 
of the verge and crown-wheel — becomes the moderator or regulator 
of the old clocks, watches, etc. The balance alone cannot produce 

Balance-Regulator. — The balance, when joined to the regulating 
spiral-spring, becomes the regulator of the modern portable clocks, 
known as watches, and also of the marine and astronomical portable 
clocks. The elasticity of the spiral-spring is to the balance what the 
weight is to the pendulum. 

Balance-wheel. — Crown, scape-wheel, rencounter-wheel. 

Balance-wheel, known also as verge and crown-wheel watches. 

282 the watchmaker's manual. 

Barrel. — A piece hollowed on the lathe, in the cavity of which a 
spring, bent in a spiral form, is placed, designed for clocks and watches. 

Bridge. — A piece bent at right angles at each end, so as to form a 
small frame to a part of the clock or watch. 

Burin, also " graver." 


Caliber. — The plate on which the arrangement of the pieces of a 
clock is traced — the pattern-plate. 

Centre of motion. — The point around which a piece revolves. 

Centre of oscillation. — This is, in the pendulum, the point about 
which all the force of the weight of the rod and the ball are united. 
This centre is below the centre of gravity. 

Centre of suspension. — The point around which the pendulum 

Centre- wheel, small, known also as " third wheel." 

Chain-guard. — Mechanism employed in watches, with a fusee to 
form a stop-work, strong enough to prevent the main-spring from being 
wound up too far, so as to avoid breaking that or the chain. 

Chick. — A synonym of " steady pin." 

Click. — A small lever movable on its centre, which pressed by a 
spring, acts upon a ratchet or saw-toothed wheel, or rack, to prevent 
its return, sustains the effort of the motive-power, and facilitates the 
winding of it. 

Click and spring- work. — The mechanism by means of which the 
motive-weight, spring of a clock, or barrel of a watch is wound. 

Clock. — The proper word used to designate any machine which 
divides and marks the fractions of time. Clocks are divided into several 
classes, according to the uses for which they are designed : — 1st, port- 
able clocks, commonly called watches ; 2d, apartment or mantel-clocks, 
usually known as clocks ; 3d, clocks for steeples or towers which are 
designated, belfry clocks. To these denominations epithets are added 
descriptive of the functions which they perform, as repeaters, alarms, etc. 

Cog-wheel. — A tooth or projection of a wheel which works into 
those of another weeel or pinion. This term is also applied indiscri- 
minately to all toothed wheels, as the term " cog " is applied indiscri- 
minately to teeth cut in every form. 

Compensation. — A mechanism by means of which we correct or 
destroy the variations of the clock which are independent of the 
machine itself, as the compensation in the pendulum or the balance of 


the variations caused by the dilatation or contraction of metals, by the 
different degrees of heat and cold. 

Concentric. — Those which have the same centre of motion. We 
say that two hands are concentric when they turn separately around 
the same centre ; thus the hour-hand is attached to a socket which turns 
on the arbor of the minute-wheel and carries the minute-hand. 

Condensation or Contraction. — Terms expressing the diminution 
of the volume of a body by cold. 

Contrate-wheel, also "fourth wheel." 

Cutting-file. — Circular files used to cut the teeth of the wheels and 
the pinions. The cutting-files are small wheels made of tempered steel, 
and are cut in saw-teeth. 

Cycloid. — Curved line formed by the revolution of a point of the 
circumference of a circle on a right line. 

Cylinder-wheel, also cylinder scape-wheel. 


Degree. — The 360th part of a circle. 

Detent. — Piece of the striking-work which checks or impels the 
train, in order that the hour may be struck, also the locking-spring of 
escapements, especially of the Earnshaw chronometer. 

Dilatation extension. — Terms expressing the increase of the volume 
of a body by heat. 

Dial-wheel, also " hour " and " minute-hand- wheel." 


Epicycloid. — The curve which should terminate the extremity of the 
teeth of the wheels, and the leaves of the pinions, in order that the 
action of the wheel may be uniform — an indispensable property in the 
gearing. The epicycloid is a curve formed by the revolution of a point 
of the circumference of a circle around another circle. 

Escapement. — That mechanism of clock-work whose functions are : 
1st, to restore to the regulator, whether pendulum or balance-regulator, 
the force which it loses at each vibration, by the friction which it 
experiences, and by the resistance of the air; 2d, while the regulator 
measures the time, the escapement regulates the velocity of the wheels, 
which indicate on the dial by their hands, the parts of time divided by 
the pendulum or by the balance. Two periods must be considered in 
the effect of the escapement ; that of the impulse restored to the regu- 

284 the watchmaker's manual. 

lator during which the wheel advances a part which equals a vibration ; 
secondly, that by which the action of the wheel and that of the motive- 
power remains suspended, while the regulator completes its oscillation. 

Escapement : dead-beat. — Those escapements in which the wheel, 
after having given the impulse to the balance, remains stationary, 
while the latter completes its vibration. 

Escapement : recoil. — That escapement which, after having received 
the impulse of the wheel — the balance finishing its vibration — causes 
the wheel to recoil ; such as the verge-escapement, the double-lever, 
anchor, etc. 

Equation of time. — The difference which exists each day of the 
year, between the true time measured by the sun, and the mean time, 
measured by clocks. 


Ferrule. — This, in the barrel, is the circle which contains the main- 

Ferrule of the spiral-spring. — A small cleft socket which is 
adjusted on the axle of the balance, to receive the inner end of the 
regulating spiral-spring ; also collet. 

Fly. — The fly is the moderator, or regulator of the trains of striking- 
work, repeaters, etc. It is formed by two large and light wings which, 
by the resistance that they experience in the air, serve to moderate the 
velocity of the wheels, and to regulate the intervals between the strokes 
of the hammer. 

Force or Power : motive. — In fixed astronomical clocks, this is the 
weight; in portable clocks, the spring. 

Frame. — That which contains the wheels and the mechanism of the 
clock ; this is composed of four pillars, and of two plates called pillar 
and upper-plate, or fire plate. 

Fusee. — A truncated cone, formed somewhat like a bell. The most 
important property of the fusee is, that of equalizing the fo^ce of the 
main-spring of watches ; so that the spring, by this valuable invention, 
becomes nearly as equal and constant a motive-power as that of the 


Gearing or Pitching. — The action of the teeth of one wheel upon 
those of another wheel or pinion, in order to make it turn around its 
centre of motion, and to transmit its motion to it. 



Isochronal. — Movements of the same duration. We generally call 
the oscillations or vibrations of a body isochronal, when they are of the 
same duration. These oscillations are naturally isochronal when the 
body that measures them constantly passes over the same extent, and 
consequently has the same velocity ; but oscillations of unequal extent 
may also be isochronal. 


Jumper. — A species of click in the repeater, preventing the motion 
of a wheel in either direction. 


Lathe. — A tool used for turning or rounding the various pieces 
employed in machines. 

Lever. — A simple machine which is the first mechanical power. The 
lever is a rod which, forming two unequal arms, and being supported 
by a rest at the point which divides them, increases the limited force 
of a man, and raises weights by the action of the longer arm. The lever 
enters into the composition of all machines, or rather these machines 
are but composite levers. 

Limb. — Circle, or portion of a circle, graduated in degrees, etc. 

Line. — The twelfth of an inch. 


Minute-wheel-works, or Dial-wheels. — These wheels are placed 
between the pillar-plate and dial, and guide the hands which mark the 
hours and minutes. 

The minute-wheel-works, in watches and ordinary clocks, are com- 
posed of the canon pinion ; the end of the socket of this, formed in a 
square, receives the minute-hand; the socket of the canon pinion is 
adjusted with friction on the pivot or elongated rod of the wheel of 
the train which revolves once in sixty minutes. The canon pinion 
gears into a wheel, the diameter of which is three times larger than 
that of the pinion, has three times as many teeth ; this pinion conse- 
quently makes three revolutions while the wheel makes one ; this latter, 
which is called the minute-wheel, therefore revolves once in three 
hours. This wheel is fixed on a pinion which conducts the dial- wheel, 
whose revolution is performed in twelve hours. The dial-wheel is 

286 the watchmaker's manual. 

fixed on a socket whose end carries the hour-wheel ; this socket turns 
freely on the socket of the canon pinion. 

Motive-power.— Any agent which gives motion to a machine. In 
fixed astronomical clocks with pendulums, the motive-power is a 
weight; in portable clocks, it is a spring. 

Movement.— We call the movement? in clockmaking, the interior 
part of the clock, which measures the time, and which marks it on the 
dial by means of the hands : this is also called the wheel- work. 

Oil.— Oil, when applied to the parts of moving bodies which rub 
against each other, diminishes their friction. Clockmakers have always 
considered olive oil to be the best adapted to lubricating the pivots of 
the numerous axles which they employ in machines for the measure of 
time ; but experience has taught them that the best and purest of these 
oils contain some injurious properties which they sought to remove 
lheir attempts have hitherto been unsuccessful, without excepting the 
process of M. Laresche, which has not effected what he promised & of it 
The learned academician, M. de Chevreil, in his important analysis of 
oleaginous bodies, has opened a way which should lead to the solution 
ot this interesting problem. He has proved that oily bodies are com- 
posed of two distinct substances; one always fluid, which he calls 
oleine; the other always solid in its pure state, to which he gives the 
name of stearine. M. Braconnet, a celebrated chemist of Nancy has 
ascertained that olive oil contains one hundred parts; twenty-eio-ht 
parts of stearine, and seventy-two parts of oleine. He employs the 
following process to effect the separation : 

He freezes the oil during the most intense cold of winter ■ he then 
compresses it during several days between several sheets of bibulous 
paper, by the aid of a strong press and in a temperature below zero 
taking care to renew the paper until it ceases to soil it He then 
presses it again in a temperature of 15° Eeaumur, and thus obtains a 
white material, which is as brittle as the hardest tallow and resembles 
it m taste and smell ; this is stearine. 

To obtain the oleine, he moistens the blotting-paper in which the 
frozen oil had been compressed, with tepid water; he then twists it in 
a knot which he subjects to the action of the press, and extracts from 
it the oleine which is perfectly fluid. Several clockmakers who have 
used that, admit that it possesses the qualities that they have Ion- 
desired. J ° 


Oscillation or Vibration. — The motion of a body which swings 
backward and forward ; the backward and forward movements of this 
body form two oscillations. 


Pallet. — A small lever carried by the arbor of the balance in the 
verge escapement. 

Pinion. — A small toothed wheel. 

Pyrometer. — An instrument designed to show, in high temperatures, 
the different degrees of dilatation and condensation, by different degrees 
of heat of metals and other bodies. 


Ratchet-wheel. — A notched wheel the teeth of which are straight on 
one side and directed towards the centre, and inclined on the other side. 
The ratchet-wheel is employed for different uses ; — the first has been to 
serve for the winding of the main-spring in the mechanism called the 
click and spring- work ; the second use of the ratchet-wheel has been 
that of being substituted for the verge and forming the escapement- 
wheel of the anchor-escapement, whether the recoil or dead-beat, etc. ; 
it is then called the ratchet-wheel of the escapement. 

Remontoir. — An especial mechanism designed to render the force 
which sustains the movement of the escapement or balance perfectly 
equal and constant, so that it may not participate in nor receive the 
unequal forces caused by the variations of the friction of the train, ine- 
quality of the motive-power, etc. Also, winding-up arbor. 

Repeater. — A mechanism adjusted to a clock or watch, by means of 
which one can cause the hour or the fraction of an hour marked on the 
dial, to be struck at any moment of the day or night. 


Second- watch, also " seconds-hand watch." 

Star- wheel. — Wheel formed by angular radii ; a part of repeating- 

Screw. — An instrument of general utility in all mechanical arts. 
The screw is a cylinder spirally grooved, and when conducted by a 
lever, acquires a force capable of moving and strongly pressing the 
bodies on which it acts. 

Snail. — A piece of the repeater, figured spirally, and formed by the 
degrees which proceed from the circumference to the centre. The 

288 the watchmakek's manual. 

hour- wheel is divided into twelve parts or degrees ; this snail deter- 
mines the number of strokes which the repeater should strike, by 
means of the rack, one of whose arms rests on one of the degrees of 
the snail. 

The quarter-snail is divided into four parts. 

Stop-work. — Mechanism employed to supply the place of the chain- 

Spiral or hair-spring.— A band of tempered steel, bent in a spiral 
form; when adjusted to the balance it becomes an integral part of 
the regulator. The spiral spring is to the balance what the weight 
is to the pendulum; the spiral-spring produces the vibrations of the 
balance and determines, conjointly with the mass and the diameter of 
the balance, the duration of the oscillations. 

Support. — A piece forming a base which serves to fix a wheel, etc. 
The support of a wheel is a socket forcibly driven on a rod in order to 
rivet the wheel there. 

Suspension. — We generally term that portion of the clock which 
supports the pendulum, so that it can oscillate freely, the suspension. 


Train. — An assemblage of several wheels and pinions which, placed 
in a frame, gear together successively in such a manner as to transmit 
to the last wheel the movement which the first received from the mo- 

Tempering. — The operation by which steel acquires all the degrees 
of hardness of which it is susceptible, either for a spring or cutting- 
tool, being blue for the former, and strawberry-red for the latter. 


Vibrations. — The swinging movement of the pendulum. These vi- 
brations regulate the movement of the clock and form the measure of 
the time. 

The balance joined to the spiral-spring has, like the pendulum, a 
vibratory movement which regulates the movement of the clock or the 


Watch. — Pocket clock. 

I 18 Ajvrl I860 

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ACADEMY. 1 voL 8vo., with numerous wood-cuts. New Edition, with large Ad- 
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