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A Brief Glossary of Technical Terms (continued)

DAMASCENING

A method of decorating the bottom plate or bridges, consisting of a radial or striped design which appears to shimmer as it catches
the light at different angles;  especially associated with American watches from the 1870s onwards.   It is actually a variety of
engine-turning and unrelated to the damascening found in mediæval weaponry, which is a technique of inlaying one metal in another.

DART

A safety device incorporated into many lever escapements to prevent the lever and the roller from getting out of
alignment.   The lever carries a pointed prong, the dart itself, between the tines of its fork;  this fits into a curved recess
in a second roller, which restrains the fork if it happens to lose contact with the impulse-pin and prevents the lever from
swinging clean out of engagement.   The dart is chiefly associated with the European anchor-shaped lever and is rarely
found in English side-lever watches.

DEBAUFRE, Pierre

(fl. 1689-1720) French watchmaker who settled in London as a Protestant refugee.   He was joint patentee with Nicolas
Facio of the technique of jewelling pivot-holes (1704), and in the same year he devised the first viable alternative to the
traditional verge escapement;  this so-called ‘club-foot verge’ had two escape-wheels and a single pallet in the form of a
horizontal disc cut away at one side and with its edges curiously angled and lop-sided (hence the name), which engaged
with each wheel alternately.   This found some favour with Lancashire makers a century or so later.

DECK WATCH

A large precision-made watch used on board ship for synchronising chronometers with one another or conveying their
readings to the deck where solar or lunar observations were performed.   For this purpose it had to be easily carried from
one part of the ship to another;  it was therefore generally provided with its own case, unlike a true chronometer.

DENNISON, Aaron L.

(1812-1895)   U.S. watchmaker, pioneer of quality mass-production, whose business, founded at Roxbury
(Massachusetts) in 1849, grew into the American Waltham Watch Company.

DETACHED

Of an escapement:  having a separate unit introduced between the escape-wheel (or the final wheel of the train) and the
balance, so that the two are in contact only when the specific processes of impulse and locking require them to be so.
Usually applied to the lever escapement, whose full name is ‘detached lever’ (to distinguish it from the rack-lever).   Lever
watches dating from the 1820s, when this system was still a novelty, sometimes have the word DETACH'D engraved
on the cock-foot.

DETENT

In an escapement, a separate component between the balance and the escape-wheel which performs the locking function,
so that the balance itself does not have its freedom of movement impaired by the need to do this.   The detent may
revolve (pivoted detent) or it may consist of an arrangement of flat springs (spring detent);  the latter, devised almost
simultaneously by Arnold and Earnshaw in about 1780, was for many decades the standard chronometer escapement.

DIAL

The ‘face’ of a clock or watch.   The familiar white or cream enamel dial began to appear at the end of the 17th century,
although gold or silver dials with various forms of decoration have never quite gone out of use.

DOME

The fixed inner back cover of an English consular case, pierced with an access hole for the winding-key.

DOUBLE ROLLER
ESCAPEMENT

A variety of lever escapement in which the balance-staff carries two rollers:  one carrying the impulse-pin and the other
with a recess which engages with the safety dart.

DRAW

A configuration of the locking face of a pallet which causes it to pull the escape-wheel more tightly into engagement
during the locking process, producing an infinitesimal recoil in the train.   The purpose of this is to prevent pallet and
escape-wheel from slipping out of engagement,

DROP

The interval between impulse and locking during which the escape-wheel, and therefore the whole train, is free to turn.

DUPLEX ESCAPEMENT

A complex escapement invented by Pierre le Roy in about 1750 but favoured chiefly by English watchmakers in the first
half of the following century.   The escape-wheel has two sets of teeth (hence the name): short ones for impulse,
engaging with a cam on the balance-staff, and long ones for locking engaging with a tiny ruby roller (which tends to wear)
likewise mounted on the balance-staff.

DUST CAP

(or dust-cover).   A protective cover fitting over the bottom plate and sides of a movement, with holes cut in it for the
winding-key and (usually) the table of the cock.  In English watches it is of gilt brass, removable and secured by a
sliding catch;  French and Swiss watches occasionally have silver dust-caps hinged to the movement.

EARNSHAW, Thomas

(1749-1829)   English watchmaker and chronometer innovator.  In early life he was a specialist maker of cylinder
escapements, and when in 1781 he devised a spring-detent escapement he was obliged to seek the co-operation of a
client, Thomas Wright.   Wright did not stir himself to obtain a patent until after John Arnold had done so, using a design
which Earnshaw believed was a piracy of his own.   Earnshaw eventually established himself as a maker in his own right,
covering the entire range of sophistication from verges to full chronometers;  he led the way in offering the latter at
reasonable prices and with some approach to volume production.   He devised the bimetallic compensated balance,
although he did not always use it himself.

ÉBAUCHE

A mass-produced movement, usually Swiss, designed to be bought in ready-made by ‘watchmakers’ who would then
finish, sign and market it as their own.   The 19th-century Swiss industry, while undoubtedly capable of producing
articles of the highest quality, was largely built upon the volume manufacture of ébauches.   Frédéric Japy, by his
invention of machine-tools and organisation of a factory system, gave the greatest impetus to this kind of activity.

ELGIN

(Elgin National Watch Co.)   U.S. manufacturer, founded at Elgin near Chicago in 1864, as the National Watch Company,
by a group of Waltham executives who saw the need for a manufacturing base beyond the traditional east-coast
locations, exploiting the rapidly expanding railroad system.   The Elgin name itself dates from 1874.  In the early 1900s
Elgin overtook Waltham as the country's largest manufacturer.

ENAMEL

A form of glass, presented in powdered form and usually coloured by means of metal oxides, which when heated (a
process called fusing) sets into a hard substance which can take a high polish.   Enamelling of various kinds was used
to decorate watch cases from very early times.   In about 1630 the French craftsman Jean Toutin discovered a means of
using it like paint, so that finely detailed portraits and scenes could be executed;  this kind of decoration became a
speciality of Geneva and remained so for centuries.

White enamel was first used for watch dials in about 1675 and gradually replaced the metal champlevé dial, becoming
dominant by about 1770.   Cream or off-white was favoured by English makers from about 1815 to 1860.   They also
adopted a matt surface from about 1810, whereas the Swiss continued to use a high-gloss finish.

END PLATE

The centre-piece of the table of the cock, in which the balance-staff pivot is located.   In English watches (those without
a jewelled endstone) it was usually of brass and soldered in place;  the French school preferred a steel plate held by
screws and often covered by a coqueret.

ENDSTONE

A jewel (ruby or, quite often in 19th-century English watches, roughly cut diamond) used as an end-plate.

ENGLAND

England was slow to develop an independent watchmaking school, and few examples by home-born makers can be
traced before 1600;  Bartholomew Newsam, employed by Queen Elizabeth I, was among the earliest.   A Worshipful
Company of Clockmakers was incorporated in 1631;  its founder-members included Edward East, who was among the
first English makers to show an independent style, breaking away from the extravagant ornamentation that had
characterised watch-cases until the 1650s.   The development of the balance-spring by Hooke and the discovery of the
technique of jewelling in 1704, coupled with the rise of distinguished craftsmen such as Tompion and later Graham and
Mudge, gave England the leadership in the eighteenth century.   By 1800, however, English domestic watch design was
beginning to stagnate;  the standard of craftsmanship remained high (supported, before the 19th century was half over,
by a surprising degree of standardisation of parts), but makers remained wedded to the fusee and to full-plate or
three-quarter-plate calibres, while French, Swiss and later American producers were moving towards slimmer layouts.
Some innovation continued, of course, especially in Liverpool where new escapements such as the rack-lever and the
Massey group were widely applied.   The First World War finally put an end to the multitude of local makers who had been
producing (or rather assembling and finishing) large full-plate fusee levers virtually without change since the 1830s,
although specialist items such as chronometers continued to be made to the highest standards through the 20th century.

ENGLISH LEVER

A name often used (especially by English makers!) for the tangential or side lever.

ESCAPEMENT

The ‘metering unit’ which, working in conjunction with the balance or other controller, breaks down the motive force of the
mainspring into controlled and regular steps by alternately delivering impulse to the balance and locking the train.   Its
main components are the escape-wheel and the pallets;  the latter may be mounted on or embodied in a separate
component (lever, spring-detent) or they may be incorporated with the balance-staff (cylinder, duplex, verge).

ESCAPE-WHEEL

The final (usually fifth) wheel of the train, bearing specially-shaped teeth which interact with the pallets.

FAKE FUSEE

(or false fusee).   A late 19th century English key-wound watch with a going barrel and an extra wheel interposed between
the great wheel on the barrel and the centre pinion.   The sole function of this extra wheel is to gratify old-fashioned
English preferences by making the winding action work anti-clockwise like that of a fusee watch.

FALSE PENDULUM

A curious fad of the late 1600s:  a miniature facsimile of the bob (flat circular weight) from the end of a clock pendulum,
attached to the rim of the balance-wheel and arranged so that it could be seen wagging to and fro.   For this purpose the
movement was sometimes rearranged so that the balance lay behind the dial, which had a slot in it through which the
bob could be observed.   There are some late 19th century revivals.

FASOLDT, Carl

(1818-1898)   U.S. watchmaker, inventor of a type of lever escapement and pioneer of the production of true marine
chronometers in the U.S.A. (commencing 1861).

FLIRT

This slightly improbable term simply means something that moves in jerks rather than continuously, like the
second-hand of a modern watch.

FOLIOT

The earliest form of controller, consisting of a pivoted beam with weights (which might be adjustable) at either end, like a
dumb-bell.   Some of the earliest watches had miniature foliots (only relatively miniature – the foliot could take up the
entire breadth of the movement) instead of balance-wheels.

FORGERY

A long-standing problem.   In the late 18th century the fashionable London maker Eardley Norton was dogged
by multitudes of cheap Swiss watches bearing his name;  a few of the makers went to the extent of counterfeiting the
English type of layout, with single-footed cock and engraving on the bottom plate;  but their coarseness of execution
usually gives them away.   Mrs. Gamp is an example.   Shortly afterwards Breguet became the chief sufferer;  most
crypto-Breguets are conventional verges of a type the Swiss master would not have touched, and they are often signed
Breguet à Paris, a form he never used.   Turkish market watches often bear false names, usually English;  Windmills or
Markwick in the 18th century, Dent in the 19th (after E. J. Dent, whose family firm built Big Ben, the clock on the Houses
of Parliament in London), even though the latter are clearly Swiss.   These old forgeries, unlike the modern fake Rolexes
and the like, were generally examples of passing-off rather than actual copies;  the forger borrowed the name but not the
features.  

FORK

The divided inner end of the lever in a lever escapement, with two prongs or tines between which the impulse-pin engages.

FORM WATCH

A watch whose case is shaped to imitate something other than a watch:  a heart, a cross, a book or even a skull.   Form
watches were popular in the late 16th century and again about 200 years later.

FOURTH WHEEL

The wheel immediately adjoining the escape-wheel.   If a subsidiary seconds dial is present, its hand will usually be fitted
directly on the end of the fourth-wheel arbor.

FRANCE

France adopted the idea of a portable spring-driven time-keeper very early;  the Coudray family of Blois were producing
‘montres’ before 1520.   Early French watches made much use of engraved decoration and their makers led the way in
using brass rather than iron for the movement.  17th-century French watches were usually very deep in calibre, with
rounded cases which gave them the nickname of ‘oignons’ (onions).  The late 1600s saw the adoption of some features
which were to persist all over Europe until the demise of the verge, such as the two-footed bridge cock and the
winding-hole in the dial.   Many French watches of this period had very large balance-wheels.   Enamel dials appeared in
about 1675, often in the form (exclusive to France) of a metal dial with twelve small enamel plaques, one for each hour.
In the 18th century the interest in fine decoration diminished and the division grew ever wider between run-of-the-mill
watches, often quite roughly executed, and the work of a few outstanding craftsmen such as the le Roy family;
increasingly these craftsmen were of Swiss origin even though they worked in Paris (Breguet, Berthoud), and by 1800 the
centre of the ‘French’ tradition had moved to Switzerland.   Since then France, like England, has been chiefly noted for
specialist work, although their field remained the domestic watch rather than the chronometer;  all the houses just
mentioned lasted throughout the 1800s and that of Breguet still exists today.      

FREE-SPRUNG

Of a balance-spring:  having no regulator attached.   As any kind of regulator effectively changes the shape of the spring
and therefore injures its isochronous quality, it has long been the practice in instruments of the highest precision to do
without the regulator.   Such a watch or chronometer relies on the timing-screws for any adjustment that may be
necessary;  and of course it is assumed that the instrument will have been built and adjusted to a very high standard of
accuracy from the start, so that such adjustment is only occasionally needed.   Free-sprung watches are therefore
treasured by collectors.

FRICTIONAL REST

In an escapement, a method of achieving locking by allowing one component to slide over another without meeting any
actual opposing force, so that there is no recoil.   A typical example is the cylinder escapement, where the cylinder itself
is configured to stop the escape-wheel teeth without pushing the wheel backwards.   By contrast, the verge is the recoil
escapement par excellence, with pallet and crown-wheel tooth meeting each other head-on.

FRONT PLATE

The plate nearer to the dial.   Certain components, such as the motion-work, set-up ratchet and (if present) repeater
mechanism, are usually sandwiched between front plate and dial.

FULL-PLATE

A full-plate movement is one in which most of the moving parts are sandwiched between two circular plates (usually of
brass) separated by turned pillars.   The balance-wheel is not fitted between the plates but generally carried outside
the bottom plate for easier access (occasionally, as in false pendulum or hebdomas watches, it may be placed behind the dial
instead).   From the early 1800s, the bottom plate in English (and some American) watches is not strictly full, being cut
away for the mainspring barrel which is then covered by a screwed-on bridge.   Until about 1780 all watches were of
full-plate contruction.

FUSEE

An ingenious device which compensates for the declining force of a mainspring as it unwinds by automatically adjusting
the gearing between the spring and the train as it runs.
The spring-barrel is not directly geared to the rest of the movement.   Instead, it pulls on one end of a fine chain whose
other end is latched into the cone (a brass drum of tapered parabolic-sided form, like a flattened pinnacle, with a spiral
channel running round it).   The chain is long enough to go four or five times round the barrel.   With the watch fully
wound, the chain leaves the cone at its narrowest point, so that the mechanical advantage is low – in other words, the
spring is in the position of a man trying to steer a car with a very small wheel or to turn a nut with a short-handled
spanner.   As the spring runs down and the chain is drawn off the cone, the diameter of the cone at the point of departure
becomes ever greater;  so too, therefore, does the leverage.   The cone incorporates a ratchet and click for the winding
mechanism and may also have maintaining power built into it.  English-style fusee watches, key-wound from the back,
are wound anti-clockwise.
The fusee is thought to have been invented by Leonardo da Vinci.   Indispensable in early watches, it became less
essential once the balance-spring had been invented and still less so as escapements improved in the 18th century.
French makers of about 1780 were the first to dispense with it as a regular practice.   By contrast, fusees were still
being fitted to English full-plate movements after 1900.


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