Chapter XXIV: Appendix: E (1)

_Encyclopedic Dictionary_

ABRASION—Wearing away by rubbing or friction.

ADAMS, J. C.—A promoter instrumental in organizing the Elgin, Illinois, Cornell, and Peoria Watch Companies, and the Adams & Perry Manufacturing Company. He invented and patented the "Adams System" of time records in use on most of the railroads in the West. He last appeared in prominent connection with the watch and clock business as the organizer of the Swiss horological exhibit at the World's Columbian Exposition.

ADDENDA—Tips of the teeth of a wheel beyond the pitch circle. Sometimes of circular outline; sometimes ogive—that is, of a shape patterned after the pointed arch. The addendum is also known as the "face" of the tooth.

ADJUSTMENT—The manipulation of the balance with its spring and staff to secure the most accurate time-keeping possible. Three adjustments are usually made, viz.: for isochronism, temperature and position. Much of the difference in value and cost of watches depends on this operation.

ADJUSTMENT TO ISOCHRONISM—Strictly speaking this would cover all adjustment; but it is technically understood to mean an adjustment of the balance spring so that the time of vibration through the long and short arcs of the balance is the same.

ADJUSTMENT TO POSITIONS—The manipulation of the balance and its spring so that a watch keeps time in different positions. Good watches are usually adjusted to five positions. They are pendant up; III up; IX up; dial up; and dial down.

ADJUSTMENT TO TEMPERATURE OR COMPENSATION—The adjustment of the balance and spring so that the time-keeping qualities are affected as little as possible by changes in temperature. See _Compensation_.

AHAZ—King of Judea, 742-727 B. C. See _Dial of Ahaz_.

ALARM—Sometimes spelled "alarum." A mechanism attached to a clock whereby at any desired time a bell is struck rapidly by a hammer.

ALUMINUM-BRONZE—An alloy of aluminum and pure copper, usually in the proportion of 10 parts of the former and 90 of the latter. It is considerably lighter than brass and highly resistant to wear.

ANAXIMANDER—Greek astronomer to whom the Greeks ascribed the invention of the sun-dial in the sixth century B. C.

ARBOR—The axle or axis on which a wheel of a watch or clock turns. Also applied to a spindle used by watchmakers.

ARC—Any section of the circumference of a circle.

ARCHIMEDES—A famous Greek philosopher and scientist sometimes credited with the invention of the clock. About 200 B. C. he made a machine with wheel work and a maintaining power but having no regulator it was no better as a time teller than a planetarium turned by a handle. It may have furnished the suggestion for later time-keeping machines.

ARNOLD, JOHN—Born 1736. An English watchmaker of note. He invented the helical form of the balance spring and a form of chronometer escapement much like Earnshaw's. Died 1799. Arnold's devices have been most useful and permanent.

ASSEMBLING—The putting together of the finished parts of a watch. In a three-quarter plate watch this is done on the lower plate. In a full plate movement it is easier and more satisfactory to assemble on the top plate.

ASTROLABE—1. An instrument of various forms formerly used especially in navigation to measure the altitudes of planets and stars. 2. A projection of a sphere upon any of its great circles.

ASTRONOMICAL TIME—Means solar time, as computed from observing the passage of the sun across the meridian from noon of one day to noon of the following day. It is counted continuously up to 24—not in two 12-hour divisions.

ASTRONOMY—The science which treats of the motions, real and apparent, of the heavenly bodies. Upon this science, through its determination of the length of the year, is founded the science of horology—or time-keeping.

AUTOMATA—FOR STRIKING—Very common on old clocks and very complicated, such as: Indian King hunting with elephants, Adam and Eve, Christ's flagellation, and many others. See _Clocks, Interesting Old_.

AUTOMATIC MACHINERY—The second great contribution of America to watchmaking after the establishment of the principle of interchangeability of parts, and making possible the effective execution of that principle.

AUXILIARY—A device attached to a compensation balance to reduce what is known as the "middle temperature error." Some are constructed to act in high temperatures only—as Molyneux's; and some in low temperatures only—as Poole's.

BALANCE—The vibrating wheel in a watch or chronometer which with the aid of the balance spring (hair-spring) regulates the rate of travel of the hands. The balance is kept in vibration by means of the escape wheel. See _Compensation Balance_.

BALANCE ARC—In detached escapements, that part of the vibration of the balance in which it is connected with the train. The remainder is called the drop.

BALANCE-CLOCK—A form of clock built before the pendulum came into use. The regulating medium was a balance on the top of the clock made with a verge escapement. See _Foliot_.

BALANCE COCK—The standard which supports the top pivot of the balance. In old watches often elaborately pierced and engraved.

BALANCE SPRING—In America usually called the "hair-spring." A long slender spring that governs the time of vibration of the balance. One end of the balance spring is fastened to a collet fitted friction-tight on the balance staff, the other to a stud attached to the balance cock or to the watch plate. The most ordinary form is the volute, or flat spiral. The other form used is an overcoil. See _Bréquet Spring_. The principle of the isochronism of a balance spring was discovered by Hooke, and first applied to a watch by Tompion. The name hair-spring comes from the fact that the first ones are said to have been made from hog bristles.

BALANCE SPRING BUCKLE OR "GUARD"—A small stud with a projecting tongue attached to the index arm and bridging the curb pins so as to prevent their engaging two of the balance spring coils. Used chiefly in Swiss watches.

BALANCE STAFF—The axis of the balance. The part of a watch most likely to be injured by a fall.

BALANCE WHEEL—A term often incorrectly applied to the balance itself, but properly it is the escape wheel of the verge escapement.

BAND—Of a Watchcase—The "middle" of the case to which the dome, bottom and bezel are fastened; the last sometimes screwed, sometimes snapped.

BANK—Banking-pin.

BANKING—In a lever watch the striking of the outside of the lever by the impulse pin due to excessive vibration of the balance. In a cylinder or verge movement the striking of the pin in the balance against the fixed banking-pin.

BANKING-PIN—A pin for restricting the motion of the balance in verge and cylinder watches.

BANKING-PINS—1. In a lever watch, two pins which limit the motion of the lever. 2. In a pocket chronometer, two upright pins in the balance arm which limit the motion of the balance spring. 3. In any watch, the curb pins which confine the balance spring are sometimes called banking-pins.

BARLOW, EDWARD (BOOTH)—A clergyman of the Church of England, born in 1636. He devoted a great deal of time to horological pursuits. He invented the rack repeating striking works for clocks, applied by Tompion in 1676. He invented also a repeating works for watches on the same plan. And he invented the cylinder escapement which he patented with Tompion and Houghton. When he applied for a patent on his repeating watch he was successfully contested by Quare, who was backed by the Clockmakers' Company. He died in 1716.

BAR MOVEMENT—A watch movement in which bars take the place of the top plate and carry the upper pivots. Sometimes termed a "skeleton" movement. Not generally adopted because its many separate bearing parts promote inaccuracies where large quantities are to be produced.

BARREL—A circular box which confines the mainspring of a watch or clock.

BARREL ARBOR—The axis of the barrel around which the mainspring is coiled.

BARREL HOLLOW—A sink cut either into the top plate or the pillar plate of a watch to allow the barrel freedom.

BARREL HOOK—A bent pin in the barrel to which the mainspring is attached.

BARREL RATCHET—A wheel on the barrel arbor which is prevented by a dog from turning backward while the mainspring is being wound and which becomes the base against whose resistance the train is driven.

BARTLETT, P. S.—One of the early watchmakers of America. Connected with the Waltham factory at first and later with the Elgin Company. It is said that he first proposed the formation of the company at Elgin. His name became familiar as a household word throughout the country from being inscribed upon a full-plate model which attained widespread success.

BEAT—The strike or blow of the escape wheel upon the pallet or locking device.

BEAT PINS—The pins at the ends of the pallets in a gravity escapement which give impulse to the pendulum.

BECKETT, SIR EDMUND—See _Denison, Edmund Beckett_.

BEROSUS—A Chaldean historian who lived at the time of Alexander the Great, about 200 B. C., and was a priest of Belus at Babylon. Said to have been the inventor of the hollow sun-dial. He was the great astronomer of his age.

BERTHOUD, FERDINAND, 1727-1807— An eminent French watchmaker and writer on horological subjects. Among his books are: "Essai sur l'Horlogerie," "Traite des Horloges Marines," and "Histoire de la mesure du Temps." He was a Swiss by birth, but lived most of his life in Paris.

BEZEL—The ring of a watch or clock case which carries the glass or crystal in an internal groove.

BIG BEN—The great bell which strikes the hours on the clock at Westminster.

BIZZLE—A corruption of Bezel. See _Bezel_.

BLOW HOLES—Places where the brass and steel of a compensation balance are not perfectly united, when they are put together with silver or solder.

BOB—The metal mass forming the body of a pendulum.

BOETHIUS, ANCIUS MANLIUS SEVERINUS, A. D. 480-524—A Roman philosopher and statesman to whom is sometimes attributed the invention of the clock. He did make a sun-dial and a water clock which latter may have contained a germ of the idea later developed into our modern clock.

BOSS—A cylindrical prominence or stud. The minute hand is carried on the boss of the center wheel.

BOTTOM—Of a Watchcase—The cover outside the dome of the case. Commonly called the "back."

BOUCHON—The hard brass tubing of which pivot holes in watch and clock plates are made; known commonly as "bushing wire." The short sections cut off for a pivot being called the "bushing."

BOW—The ring of a watch case to which the guard or chain is attached; also known as "pendant bow."

BOX CHRONOMETER—A marine chronometer.

BOXING-IN—Fitting the watch movement in its case; applied chiefly to the encasing of stem-winding movements.

BRÉQUET, ABRAHAM LOUIS—A celebrated Swiss mechanician and watchmaker born at Neufchatel in 1747. He made several improvements in watches, the most notable being the Bréquet hairspring still in use in the best watches. He died in 1823.

BRÉQUET SPRING—A form of balance spring which is a volute with its outer end bent up above the plane of the body of the spring and carried in a long curve towards the center near which it is fixed. Like all other springs in which the outer coil returns towards the center, it offers opportunities of obtaining isochronism by varying the character of the curves described by the outer coil and thus altering its resistance. So-called from its inventor, Abraham Louis Bréquet (q. v.). Its advantage over the flat spring is that the overcoil allows expansion and contraction in all directions, thereby avoiding a good deal of side friction on the pivots as well as insuring more nearly perfect isochronism in changes of temperature.

BRIDGE—A standard fastened to the plate, in which a pivot works.

BRIDGE MODEL—The term given to watch movements in which plates or bridges carrying the upper pivots of the train rest firmly on the lower or dial plate and are held rigid by steady pins on lower side of the plate; the bridge being secured direct to the dial plate by screws termed plate or bridge screws. This is the most common construction of present-day manufacture and is utilized in three-quarter plate or separate and combination bridges covering one or more pivots of train wheels. Its alternate is "pillar model."

BUCK, D. A. A.—A watch repairer in Worcester, Mass., who designed a model for the Waterbury watch. His first model was not successful, but in 1877 he completed one which, a little later, the Waterbury Company, with Buck as master watchmaker, started to make. He remained with the company until 1884.

BUSH—A perforated piece of metal let into a plate to receive the wear of pivots.

BUTTING—The engaging of the tips of the teeth of two wheels acting in gear. The proper point of contact being in the line of the shoulders of the teeth, butting is remedied by setting the wheels farther apart.

BUTTON—The milled knob used for winding and setting a keyless watch.

CALCULAGRAPH—Trade name for a device for automatically computing and recording elapsed time in connection with factory jobs and other work where it is necessary to show the amount of labor used.

CALENDAR—A system of dividing the year into months and days. The principal calendars known to history are: the Julian calendar; the Gregorian calendar; the Hebrew calendar; the Mohammedan calendar; and the Republican calendar. None of them has been quite accurate in dividing up the solar year, and frequent arbitrary corrections are necessary to secure a practical approximation. See descriptive article under each title.

_Julian_—Established by Julius Caesar, 46 B.C., to remedy existing defects in the Roman calendar then in use. The Julian year was based on the assumption that the solar year is 365¼ days—which was 11 minutes and 14 seconds too long. The scheme adopted was to make the regular calendar year 365 days, and to add one day every fourth year. The Julian calendar is still in use by Russia and Greece, where the dates now differ from those of most other countries by 13 days.

_Gregorian_—Established October 15, 1582, by Pope Gregory XIII, in correction of the obvious errors of the Julian calendar. It is the calendar now in use by nearly all civilized nations. The mean length of the Gregorian year is 365 days, 5 hours, 49 minutes and 12 seconds—26 seconds longer than the actual solar year. Correction is made by adding a 29th day for February every fourth year, excepting when the date of said fourth year is divisible by 100. If, however, the date is also divisible by 400, the extra day is added.

_Republican_—The calendar of the French Revolution (1793) declared to begin at midnight on the meridian of the Paris Observatory preceding the true autumnal equinox, September 22, 1792. There were 12 months of 30 days each and 5 or 6 "extra days" (as might be necessary) at the end of the year to bring the new year nearest to the then position of the equinox. Abolished January 1, 1806.

_Hebrew_—Composed of 12 lunar months, a thirteenth month being added from time to time to secure correspondence of the months with the passing seasons. The months are arbitrarily arranged to have alternately 29 days and 30 days. The length of the calendar year varies from 353 days to 385 days.

_Mohammedan_—Based on a lunar year of 354 days divided into 12 lunar months which are alternately 29 and 30 days in length. During each period of 30 years a total of 11 days are added one at a time at the end of a year. The lack of co-ordination with the solar year results in a total separation of the seasonal year and the calendar year. In use in Turkey and some other Mohammedan countries.

CALENDAR CLOCK, OR WATCH—A clock or watch which indicates days and months as well as hours.

CALIPER—The scheme of arrangement of a watch train, or the disposition of the parts of a watch.

CAM—A rotating piece either non-circular or eccentric, used to convert rotary into linear reciprocating motion, oftener irregular in direction, rate, or time.

CANNON PINION—The pinion to which the minute hand is attached. It is tubular in form (whence its name), the main arbor passing through it friction-tight.

CANTON BERNE—The Swiss district which does the largest export business in silver and base metal watches in Switzerland. The cantonal government has done everything possible to promote the industry, among other things: 1. Established information offices in the principal watch-making centers. 2. Established a permanent exhibition of articles used in the industry. 3. Established schools and associations and protective territories. 4. Prepared statistics and means for negotiating commercial relations.

CAP—The part of the case that covers the movement.

CAPPED JEWEL—A jewel having a protective end-stone.

CARILLON—Chimes frequently used in the earlier clocks for striking the hours. Still used in some clocks.

CARON, PETER AUGUSTUS—A famous Paris watchmaker, afterward called Beaumarchais, who made the first keyless watch of which we have any account.

CASE—The metal box in which the movement of a watch is inclosed.

CASE-SPRINGS—The springs which cause the outer bottom of a watch case to fly open when the lock spring is released.

CENTER OF GYRATION—That point in which the whole mass of a rotating body might be concentrated without altering its moment of inertia.

CENTER OF OSCILLATION—That point in a pendulum at which, if the whole mass of the pendulum were collected, the time of oscillation would be the same.

CENTER SECONDS OR SWEEP SECONDS—A long seconds hand moved from the center of a watch dial, as are the minute and hour hands.

CENTER STAFF—The arbor attached to the center wheel which carries the minute hand.

CENTER WHEEL—The wheel in ordinary clocks and watches placed in the center of the frame on whose arbor the minute hand is carried. It is intermediate between the barrel and the third wheel.

CHAMFER—To cut away to a bevel the right angle formed by two adjacent faces as of a jewel or stone. It is also occasionally used to signify channeling or grooving.

CHASING—A form of ornament for metals which is made by punching or pressing from behind to present the pattern in relief instead of by cutting away the material.

CHOPS—In a pendulum clock the blocks, usually of brass, between which the top of the pendulum suspension spring is clipped to prevent its twisting as it swings.

CHRONOGRAPH—In general, a recording clock or watch. Specifically, a watch with a center-seconds hand which may be stopped, started or returned to zero at will by pressing a button. Used for timing races, or measuring other short spaces of time with great exactness.

CHRONOMETER—Any very accurate time-keeper. Usually understood to mean a time-keeper fitted with a spring detent escapement. They usually have a fusee and a cylindrical balance spring.

CHRONOMETER, MARINE—Probably the most exact form of time-keeper, especially for use on shipboard. The driving power is a mainspring acting by a chain on a fusee, and governed by what is known as the Chronometer or Detent Escapement, with, as a rule, the cylindrical balance spring. The movement is mounted on gimbals in an air and water-tight brass case, maintaining the dial constantly in a horizontal position.

CHRONOSCOPE—A clock or watch in which the time is shown by figures presented at openings in the dial.

CHURCH, DUANE H.—Credited with having contributed more to the automatic features of watch machinery than any other man. He was born in Madison County, N. Y., in 1849. At 16 he was apprenticed to a watchmaker of St. Paul, Minn., and after working at the trade for 17 years, he became in 1882 the master watchmaker for the Waltham Watch Company. Besides his invaluable contributions to automatic machinery, he improved the general design of watch movements and invented a form of pendant setting which enables stem-winding movements to be set in cases not especially adapted to them. He died in 1905.

CIRCULAR ERROR—The difference in time arising from the swinging of a pendulum in a circular arc instead of its true theoretical path which is a cycloidal arc. This caused much trouble in the early clocks. Huyghens attempted to correct it (see _Huyghens' Checks_) but found that his device caused greater error. With the heavier pendulum and shorter arcs of vibration this error becomes negligible. The suspension of the pendulum by a flat flexible spring instead of a cord, attributed to Dr. Hooke, served to make the path practically cycloidal.

CLEOPATRA'S NEEDLE—An Egyptian obelisk at whose base a dial was marked. Now in London. Another similar obelisk from Egypt is in Central Park, New York City.

CLEPSAMMIA—The sand-glass, more familiarly known as the hour-glass. See _Hour-glass_; _Sand-glass_.

CLEPSYDRA—A device for the measurement of time by the flow of running water. Its simplest form is a vessel filled with water which trickles or drops slowly from a small aperture into another vessel. One or the other of the vessels is graduated and the height of the water in that one at any given time indicates the hour. Sometimes a figure floating on the water points to the hours. Later, falling, or running, water was made to turn wheels or to move a drum, as in "Vailly's clock." Clepsydras were made and improved up to the 17th century. The earliest known example—one in China—is credited with having existed in 4000 B. C. The name indicates the stealing away of water and is derived from two Greek words meaning "water" and "to steal." A common form of clepsydra in India was a copper bowl with a small hole in the bottom floating on water. When the bowl filled and sank the attendant emptied it, struck the hour upon it and floated it again on the surface of the water. Like the sun-dial, the clepsydra was invented so long ago that there is no authentic record of its origin. Its evident advantages are exactly those which the sun-dial lacked. It is quite independent of day or night or other external conditions; it is conveniently made portable; and by regulating the size of the aperture through which the water flows, it can be made to work slow or fast so as, within considerable limits, to measure accurately and legibly long or short intervals of time.

The disadvantages of the clepsydra were, first, that the hole in the container tended to become worn away so as to let the water out too fast; and second, that the water ran faster from a full vessel than from one nearly empty, because of the greater pressure. This latter was in classic times corrected by a clepsydra consisting of two vessels. The second and larger of these was placed below, the water running _into_ it, out of the first. A float within this larger vessel rose regularly as it filled, and carried a pointer which marked the time. The first vessel from which the water ran into the second, was provided with an overflow, and kept constantly full up to this level; so that the flow of water into the larger vessel remained constant.

Once well established and understood in principle, the clepsydra became widely known over the ancient world, and underwent a variety of improvements and modifications in form. These latter chiefly dealt with making it more legible. Means were devised, for instance, to make it ring a bell when the water reached a certain height. And thus the alarm principle was very early brought into use. Later on, after the development of mechanical devices like the pulley and the toothed wheel or gear, the pointer was by these means constructed to move faster or slower than the rate at which the water rose, or to revolve upon a circular dial on which the hours were marked. And thus we owe to the clepsydra the origin of the modern clockface as well as of the alarm. Later still, by a more complex ingenuity, devices were arranged to strike the hours or to move mechanical figures, in fact, to perform all the functions of a clockwork which was both driven and regulated by hydraulic power. The single hour hand, however, remained in place of our two or three hands moving at different speeds, as in the modern clock or watch. The clockwork also remained primitive in construction compared with our own. Clepsydrae were always expensive, because accurate mechanical work was never cheapened until modern time. Rather they were made marvels of patient ingenuity and lavish ornament. Cunning oriental craftsmen spent their skill upon elaborate mechanism and costly decorations. The clepsydra thus became first what other time-pieces later became—a triumph of the jeweler's craft—a gift for kings. And the Greeks, who beautified everything that they touched, made it at once more accurate and more artistic.

The clepsydra may thus fairly claim to have been the first _mechanical_ device for measuring time, as contrasted with the sun-dial which was really an astronomical instrument; and thus the direct ancestor of the mechanical clocks of later days. Some authorities, indeed, on the strength of certain very ancient allusions to its use in China and elsewhere, claim for it an antiquity prior to the sun-dial itself. There seems, however, to be no reason for supposing that the discovery of a mechanical law like the regular flow of water antedated so obvious a discovery as the motion of a shadow upon the ground. The explanation is probably that the invention of the clepsydra did precede the scientific perfecting of the sun-dial by the inclinations of the gnomon; which may have taken place about the time of the correction of the Babylonian calendar in 747 B. C. Not long after this date we meet with frequent references to the placing of a clepsydra in the public square of some old city, or to its use in astronomical calculations. To this, of course, its property of running by night was peculiarly adapted.

Although the chief defects of the clepsydra were minimized by the use of the two vessels and by making the aperture through which the water ran of gold or some other substance which would wear away very slowly, yet there remained certain minor imperfections. The water could not be kept entirely from evaporating; it had to be emptied out at intervals and the reservoir refilled; its accuracy was affected by the expansion of the parts under change of temperature, or it might even freeze. These faults were obviated in the sand-glass or hour-glass which for short intervals of time was also more convenient.

The clepsydra remained in use until clocks became superior to it in accuracy. See _Clocks, Interesting Old_; _Charlemagne_; _Vailly_.

CLERKENWELL—A district on the north side of the city of London within the metropolitan borough of Finsbury. It is distinguished as one of the great centers of the watchmaking and jewelers' industries in England and long established there. The Northampton Polytechnic Institute, Northampton Square, has a department devoted to instruction in all branches of the trade.

CLICK—The click, pawl, or dog, is a necessary accessory of a ratchet wheel. It is a finger, one end of which fits into the teeth of the ratchet, while the other is pivoted on its tangent. The ratchet is thus prevented from turning backward.

CLOCK—Specifically, a time-piece not made to be carried about but to stand upon a shelf or table, hang upon a wall or as built into a tower. Formerly the term signified particularly a time-piece which struck the hours. The word has its origin in the word for _bell_ in Latin, _gloccio_; Teutonic, _glocke_; French, _cloche_; and Saxon, _clugga_. At one time the term was used to denote timekeepers driven by weights as distinguished from those driven by springs.

CLOCK-WATCH—A watch which strikes the hours in succession, as distinguished from repeaters. Popular in the eighteenth century.

CLOCK, BANJO--A wall clock, so called from its shape, designed by Simon Willard, of Massachusetts and very popular in its time.

CLOCK, BIRD-CAGE—An old form of English clock whose manufacture has been discontinued—it is the oldest form of English clock still doing service. Its main feature is the endless chain drive. These clocks run thirty hours.

CLOCK, BRACKET—A form of clock very popular in England during the reign of Charles II, made to stand on a bracket or table and intended to be seen from all sides. These clocks had either a handle on top or one on each side. They were very beautifully finished.

CLOCK, CANDLE—Wax or tallow candle, usually twelve inches long and marked with circular lines one inch apart. The candle would burn one inch every twenty minutes or three inches an hour. Invention credited to King Alfred the Great.

CLOCK, GRANDFATHER'S OR LONG-CASE—A tall clock with an anchor escapement popular thru-out the later 18th and early 19th centuries in England and America. Its excellent timekeeping qualities are due to the very long and heavy pendulum which allows a small arc of vibration. Not often made at present.

CLOCK, HOOD—A style of clock originating and very popular in Holland during the late 17th century. Made of various woods, carved and ornamented and named from the hood or dome on top.

CLOCK, LAMP—A long glass tube upright on a metal stand similar in shape to the old Roman lamps. Figures were painted on the tube to indicate the hours—"12" in the middle section, with "11" above and "1" below the "12." The lamp was filled with oil up to the hour at which it was lighted—then as the oil burned away the time was indicated. This form of clock was used at night in Dutch and German rural homes until a comparatively recent date.

CLOCK, LANTERN—Same as Bird-Cage Clock.

CLOCK, LARGEST IN WORLD—The Colgate clock in Jersey City is claimed to be twice as large as the next largest clock in the world. Its dial can be read for four miles and weighs six tons. Its minute hand is twenty feet long and the tip of it travels more than half a mile per day.

CLOCK MYSTERIES—Glass Dial—A perfectly transparent dial behind which no movement was visible. The hands were caused to revolve by watch works and semi-circular weights in the counterpoise of the hands.

CLOCK, OLDEST IN AMERICA—A clock owned by the Philadelphia Public Library—over two centuries old. It was made in London and is said to have been owned by Oliver Cromwell.

CLOCK, SHEEP'S-HEAD—A clock similar to the bird-cage or lantern clock in which the dial face projects an inch or two beyond the frame.

CLOCK, SKELETON—A clock whose works are covered with glass as a protection from dust, but are without a case, the works being exposed to view. There are eight skeleton clocks in the Charles Mifflin Hammond collection at the Essex Institute in Salem, Massachusetts.

CLOCK, TURRET—A large clock in which the dials are distinct from the movement. Because of the exposure of the hands to the wind and snow, of the clock to dust and dirt, and of the oil to freezing temperature, turret clocks to keep time must be fitted with some device to obtain a constant force on the pendulum. The first used was the remontoire but since the invention of the gravity escapement for the Westminster clock by Sir Edmund Beckett this has been used instead.

CLOCK, "WAG ON THE WALL"—A wall clock typical of the North of Holland in which weights and pendulum hung below the clock case, entirely unenclosed.

CLOCK AND WATCH MAKERS, ENGLISH, EARLY—For extensive lists, dates, places, and notes, see: Old Clocks and Watches & Their Makers, by Frederick J. Britten; Worshipful Company of Clockmakers, London, Published by E. J. Francis and Co., London, 1875; Old Clock Book, by Mrs. N. H. Moore.

FRENCH, EARLY—See: Old Clocks and Watches and Their Makers, by F. J. Britten.

SCOTTISH, EARLY—For extensive list with dates, places and notes, see: Old Scottish Clock Makers, by John Smith.

CLOCK MAKERS, AMERICAN, EARLY—For lists, dates, places, and notes, see: Old Clock Book, by Mrs. N. H. Moore; American Clockmaking—Its Early History, by Henry Terry.

CLOCK MYSTERIES; TORTOISE IN WATER—Nicholas Grollier during the first part of the eighteenth century made many mysterious timekeepers. One was a metal dish filled with water in which floated the figure of a tortoise always keeping his nose to the correct time.

BALL OF VENICE—This was a sphere—its upper and lower parts gold, and about the middle a silver band bearing the numerals. As the band revolved a Cupid's wing pointed to the hour. Its action was simple. The cord which suspended it was wound about a cylinder. The weight of the ball constituted the driving power. It had a verge escapement. The maker is not known.

DOUBLE GLOBE—Constructed of two clear glass globes, the smaller one for the minutes above the larger hour globe. The mechanism for the latter was in the base, and for the minute globe, in the cap of the hour globe. Made by Henri Cunge.

CLOCKS, INTERESTING OLD: _Anne Boleyn's_—A clock said to have been presented to Anne Boleyn by Henry VIII on their wedding morning. It is about four inches square and ten inches high, of silver gilt "richly chased, engraved, and ornamented." The weights are of lead covered with copper, gilt and engraved. On one are Henry's and Anne's initials, and true lovers' knots. On the other simply H. A. At the top of each weight is "Dieu et mon droit," at the bottom "The most happye." On the top of the clock is the figure of a lion holding the arms of England, the same being engraved on the sides. The clock is now silent. There is no record as to its maker.

_Canterbury_—This was the third of the large clocks in England. It was constructed in 1292.

_Charlemagne's_—In 807 the King of Persia sent Charlemagne a bronze water clock inlaid with gold. The dial consisted of twelve small doors representing the hours. Each door opened at the hour it represented and the correct number of balls fell out upon a brass bell. At twelve o'clock twelve horsemen appeared and shut the doors.

_Coblentz_—At Coblentz in a tower on the Kaufhaus is a brazen head which gnashes its teeth as the hours strike. For a Coblentzer to say "How is the man in the Kaufhaus" means "How goes it with Coblentz and the good people there?"

_de Vick's_—In 1364 Henry de Vick set up a clock in the tower of the palace for Charles V. It was regulated by a balance. The teeth of the crown wheel acted upon two small levers called pallets which projected from and formed part of an upright spindle or staff on which was fixed the balance. The clock was regulated by shifting the weights placed at each end of the balance. On the bell of this clock the signal for the massacre of St. Bartholomew's was struck.

_Dondi's at Pavia_—Built in 1344, by James Dondi, similar to Wallingford's clock.

_Exeter_—A clock built in Exeter Cathedral sometime in the 14th century. One erected there in 1480 has the sun—a fleur-de-lis which points out the hours as it revolves around a globe representing the earth. A black and white ball represents the moon's phases by turning on its axis.

_Frederick II_—The Saladin of Egypt presented Frederick II of Germany with a clock in the year 1232. It resembled internally, a celestial globe, in which figures of the sun, moon, and other planets moved impelled by weights and wheels. There were also the twelve signs of the Zodiac which moved with the firmament.

_Hans von Jena's_—An old clock in Saxony at the top of which is a very ugly head. As the clock strikes a pilgrim offers an apple on a stick to the open mouth and then withdraws it. At the same time an angel opposite the pilgrim raises her eyes from her book. The legend goes that Hans von Jena, for a crime, was condemned to undergo such torture for three centuries.

_Jefferson's_—An old weight clock in which the weights are carried over a pulley and made to indicate the day of the week by their position. This is in the hallway at Monticello.

_Lists and Descriptions of_—See Curiosities of Clocks and Watches, E. J. Wood. Old Clocks and Watches and their Makers, F. J. Britten. Old Clock Book, N. H. Moore.

_Vase Clocks of Marie Antoinette_—The movement was inclosed in a marble pedestal. About the beautifully tinted porcelain urn was a double band, on which were marked the numerals and which revolved every twelve hours. A serpent with head erect pointed to the hour.

_Mary, Queen of Scots_—Skull Watch or Clock. A small clock in the form of a skull said to have been given by Mary, Queen of Scots, to Mary Seaton, one of her maids of honor. The skull is of silver gilt and is engraved with figures of Death, Time, Adam and Eve, and the Crucifixion. The lower part of the skull is pierced to emit the sound when it strikes, being cut in the form of emblems of the Crucifixion. The works occupy the brain's position in the skull fitting into a silver bell which fills the entire hollow of the skull. The hours are struck on this bell by a small hammer on a separate train.

POPE SIXTUS'—Built by Habrecht of Strasburg in 1589. It greatly resembles the Strasburg clock which Habrecht also built. It was in the possession of the Popes for more than two centuries and later became the property of William I, King of the Netherlands. In 1850 it was exhibited in England after which it became the property of Mr. O. Morgan. It performs all the feats of the Strasburg clock.

_Rouen_—In the Rue de la Grosse Horloge in Rouen a clock made by Jehan de Fealius in 1389 is built in a tower which surmounts an arched gateway. Its dial is about six feet square. It shows the hours, days of the week, and phases of the moon. It still keeps excellent time and is the chief clock of the city.

_St. Dunstan's_—Erected in 1671 above the gateway of the old St. Dunstan's Church. The clock had two dials, back to back upheld by a quaint bracket. In a little open belfry above were the gaily painted figures of Gog and Magog which struck the quarters on bells suspended near them. In 1830 the clock was sold to the Marquis of Hertford who set it up at his home in Regent Park.

_St. Paul's_—A clock existed prior to 1298 in the tower of St. Paul's Cathedral which struck the hours by means of mechanical figures called Paul's Jacks. Later a fine dial was added.

_Strasburg_—Rebuilt twice after the first one which was begun about 1352. This first clock consisted of a calendar which showed the principal movable feasts. It showed also the movements of the sun and moon. On the upper part was a statue of the Virgin before which at noon the figures of the three Magi bowed. At the same time a cock automaton opened its beak, flapped its wings and crowed. 2. The second Strasburg clock was erected about 1570. This was a very elaborate mechanism, showing besides the time, a calendar for a century, the movements of the sun and moon, eclipses of the same and other things. The striking was done by an elaborate automatic arrangement. (See Old Clocks and Watches & Their Makers—F. J. Britten.) 3. In 1842 the clock was again thoroughly reconstructed. This, too, is a very elaborate system of motions showing the movements of sun, moon, and planets, also sidereal time, a calendar, etc. The hours and quarters are struck by automatic figures.

_Ulm_—In the eastern end of the old Rathaus at Ulm is installed an astronomical clock which dates from the beginning of the 16th century. It was thoroughly repaired in 1549 by the builder of the Strasburg clock—Isak Habrecht. Shows in addition to the hours, the diurnal and annual revolutions of the earth and the movements and phases of the moon. The clock is an artistic achievement as well as a mechanical wonder.

_Vally's_—A scientific water clock. It consisted of a tin cylinder divided into several small cells and suspended by a thread fixed to its axis, in a frame on which the hour distances fixed by trial were marked. It was so made that the water passed slowly from one cell to the next and as it did so it changed the center of gravity of the cylinder and set it in motion so as to indicate the time on the frame. Made about 1690.

_Wallingford's_—Built in 1326 in St. Alban's Monastery. It showed besides the hours, the apparent motion of the sun, the ebb and flow of tides, changes of moon, etc. It continued to run until the time of Henry VIII. Held by some to have been a mere planetarium.

_Wells Cathedral_—Clock built by Peter Lightfoot, A. D. 1340 at Glastonbury and removed to Wells Cathedral during the Reformation, after the dissolution of the Glastonbury monastery. In 1835 it was again removed to the South Kensington museum. At that time the worn-out works were replaced by a new train, but the dial and knights were retained. The dial is divided into twenty-four hours and shows the motion of the sun and moon. On its summit are eight armed knights tilting at one another, lance at rest by a double rotary motion.

_Westminster_—A clock said to have been erected at Westminster with the proceeds of a fine imposed upon one of the Chief Justices about 1288. About 1365 Edward III had a stone clock tower erected at Westminster. This tower contained a clock which struck the hours on a great bell. It also contained other bells. This tower was razed by the Roundhead mob about 1650. Later a dial with the motto "Discite justiam monite" was placed on the site. The bell "Great Tom" was given to St. Paul's about the beginning of the 18th Century. The present Westminster clock is made after plans by E. B. Denison (Sir Edmund Beckett) and made by E. J. Dent. The bell is called "Big Ben." It is claimed to be the best timekeeper of its kind in the world. It was for use in this clock that Denison invented his gravity escapement.

_Wimborne_—A very old clock at Wimborne in Dorsetshire, much like the Wells Cathedral clock. By some authorities believed also to have been planned by Peter Lightfoot.

CLOCK-SETTERS—During the early history of turret clocks, for each one was employed a caretaker called the "setter." That such an official was needed indicates that they were more or less undependable.

COCK—A horizontal bracket. See: _Balance Cock_; _Escape Cock_; _Pendulum Cock_; _Potance_.

COLLET—A collar or flange on a cylindrical piece of metal. Any part of such cylinder of greater diameter than the rest. Sometimes of the same piece of metal; sometimes fitted friction tight upon it.

COMPENSATION—The provision made in a clock or watch to counteract the expansion and contraction due to variations of temperature. In the clock it is applied to the pendulum; in the watch to the balance.

COMPENSATION BALANCE—A balance corrected for errors caused by variations in temperature. The type in most general use was invented by Thomas Earnshaw in the second half of the 18th century. The double rim of this balance is constructed of brass and steel soldered together in the form of a cut ring, the brass on the outside. When heat, elongating the balance ring, causes it to vibrate more slowly, the brass, expanding more than the steel, bends the free ends of the cut rim toward the center, thus decreasing the diameter of the balance and quickening the vibration. On the other hand, when cold, contracting the ring tends to quicken the vibration of the balance, the contraction of the brass rim draws the free end outward, making the diameter larger and the vibration slower in consequence. The compensation balance is also made with brass as the inner metal and aluminum outside.

COMPENSATION CURB—A laminated bar of brass and steel or aluminum and brass fixed at one end, the free end carrying the curb pins that regulate the length of the balance spring. Common in old watches but not now in use.

COMPENSATION PENDULUM—A pendulum so constructed that the distance between the point of suspension and the center of oscillation remains constant in all temperatures. See: _Pendulum, Gridiron and Pendulum, Mercurial Compensation_.

CONTRATE WHEEL—A wheel whose cogs are parallel to its axis and whose axis is at right angles to the axis of the wheel into which it gears. A crown wheel.

CORROSION—The eating or wearing away of metals by slow degrees through chemical action.

COUNTERSINK—To enlarge the outer end of a hole for the reception of the head of a screw, bolt, etc. The term is also applied to the tool with which the countersink is formed.

COVENTRY—A municipal, county, and parliamentary borough of Warwickshire, England. One of the important watchmaking centers of Great Britain.

CROWN WHEEL—A wheel whose teeth project at right angles to the plane of the wheel. A contrate wheel. The escape wheel of the verge escapement is an illustration.

CRUTCH—A light rod in a clock descending from the pallet arbor and ending in a fork which embraces the pendulum rod. It transmits the motion of the pallet to the pendulum.

CTESIBUS—A famous Greek mechanician who lived in Alexandria about 130 B. C. Although his was not the first clepsydra as is claimed by some it was an ingenious and interesting one. Believed to have first applied toothed wheels to clepsydrae about 140 B. C.

CURB PINS—See _Banking Pins_.

CUSIN, CHARLES—A watchmaker from Autun, Burgundy, who laid the foundation for the Swiss watch industry in Geneva in 1587. It grew very slowly at first—in 1687 having only one hundred watchmakers with three hundred assistants. In 1760 there were at Geneva eight hundred watchmakers with 5,000 to 6,000 assistants.

CUSTER, JACOB D.—(1809-1879.) A Pennsylvania clockmaker in 1831; he was one of the early makers of watches in America in 1840. However, his work was not important commercially, for he produced only about a dozen watches. A very ingenious man, who, it is said, made everything from a steam engine to his own shoes. He made hundreds of the clock movements which at that period were used to revolve the lanterns in lighthouses.

CYCLE OF THE SUN—A period of twenty-eight years, after which the days of the week again fall on the same days of the month as during the first year of the former cycle. It has no relation to the sun's course but was invented for the purpose of finding out the days of the month on which the Sundays fall during each year of the cycle. Cycles of the sun date from nine years before the Christian era.

CYCLOID—A curve generated by a given point in the circumference of a circle which is rolled along a straight line always in the same place. Example: The curve traced by any point in the rim of a wheel which travels in a straight line along a level road.

CYLINDER ESCAPEMENT—See: _Escapement, Cylinder_.

CYLINDER PLUGS—Plugs fitted into the ends of the cylinder of a cylinder escapement. Their outer extremities are formed into the pivots on which the cylinder rotates.

DAMASKEEN—To decorate a metal by inlaying other metals or jewels, or by etching designs upon its surface. To be distinguished from snailing, with which it is often confounded.

DAY—The time of one complete revolution of the earth on its axis. The actual length of this day is continually changing owing to the eccentricity of the earth's orbit and the angle of the ecliptic. The mean solar day is 24 hours. The sidereal day is 23 hours, 56 minutes, 4.099 seconds.

DAY, NAUTICAL—The nautical day begins when the sun is on the meridian and eight bells are struck. The day is divided into "afternoon watch" or four hours, two "dog watches" of two hours each, then "middle watch," "night watch," "morning watch" and "forenoon watch," each of four hours, completing the day.

DENISON, EDMUND BECKETT—Sir Edmund Beckett—Lord Grimthorpe. Born 1816. A lawyer by profession, and the inventor of the gravity escapement for turret clocks; also an authoritative writer on horological subjects. He designed and planned the Westminster clock said to be the best timekeeper of its kind in the world. Died 1905.

DENNISON, AARON L.—Born in Freeport, Me., in 1812. Died Birmingham, England, January 9, 1898. At eighteen he was apprenticed to a watchmaker. Later in working at the trade, he was impressed with the inaccuracies which existed in the best handmade watches. This, with a visit to the Springfield Armory, gave him his idea of machine-made watches with interchangeable parts. He interested Edward Howard in the project, and having found the needed capital they started in the business and laid the foundation of what is now the Waltham Watch Company. Dennison has been called the "father of American Watchmaking" tho there seems ground for the claim that he shares that honor with Edward Howard.

DEPTHING—The technical name for the proper adjusting or spacing of the gearing in a watch.

DETENT—The device which halts, and releases, at the proper instant the escapement of a clock or chronometer. See: _Escapement_.

DE VICK, DE WYCK, OR DE WIECK, HENRY—A German clockmaker who, in 1364, made the first turret clock of which reliable information and description remains. The clock was made for Charles V. See: _Clocks, Interesting Old—De Vick's_.

DIAL—Commonly called the face of the watch—made of gold or silver or other metal or of enamel, with the required figures—in the United States one to twelve upon it in a contrasting color. See also, _Sun-dial_.

DIAL FEET—Short wires soldered to the back of the dial of a watch or clock which hold it in place by fitting into holes in the pillar plate.

DIAL OF AHAZ—A sun-dial belonging to Ahaz, King of Judea 742-727 B. C., mention of which occurs twice in the Scriptures—II Kings, XX: 9-11, and Isaiah XXXVIII: 8. It is believed that one of his Babylonian astrologers constructed it for him.

DIAL PLATE—See _Lower Plate_.

DIAL, SUN—See _Sun-dial_.

DIAL WHEELS—The wheels constituting the motion work of a watch.

DIURNAL—In an astronomical sense, pertaining to a period covering a mean solar day. See: _Solar Time_.

DOG SCREW—A screw with an eccentric head used to attach a watch movement to a dome case.

DOG-WATCH—A nautical term for two daily two-hour periods of watching aboard ship. The first begins at 4 P. M., the other at 6 P. M.

DOLMEN—A sacred instrument used for astronomical purposes at certain critical periods of the year; formed of four stones at the cardinal points and a leaning stone crossing diagonally and forming with the east stone a sacred "creep-way." The solar hours were indicated by the shadow of the leaning stone touching various prominent points or edges. One at Camp, England, is prehistoric.

DOME—The inner case of a watch which snaps on the band of a case.

DOME-CASE—A case in which the inner case or dome snaps to the band of the case.

DONDI, GIACOMO—Born at Padua, Italy, in 1298. In 1344 he set up at Padua a famous clock which became a model for later clocks and which earned for him the surname, "Orologio."

DOUBLE BOTTOM CASE—A watch case in which the inner cover or bottom is made solid with the middle. The vogue in English cases for a long time; now almost obsolete.

DOUBLE-SUNK DIAL—A dial in which there are two sinks; one for the hour hand, and a deeper one for the seconds hand.

DRAW—1. The force which holds the lever against its bank, due chiefly to the angle of the locking face of the pallet stone. 2. The angle of the locking faces of pallets in the lever escapement.

DRIVER—Of two wheels working together, the one which imparts the power. The driven wheel is termed the follower.

DRIVING WHEEL—In a clock the wheel on the main arbor which drives the whole train.

DROP—That part of the motion of the escape wheel when it is not in contact with the pallet.

DRUM—The cylinder, or barrel, on the main arbor in a clock on which the driving cord winds, raising the weight, when the clock is being wound.

DUMMY WATCH—(Fausse Montre.) About 1770 it became the fashion to wear two watches. But because two real watches were too expensive for most people, the custom grew up for having one sham watch—usually worn on the right side. These were called "dummy watches" or "fausse montres."

EARNSHAW, THOMAS—1749-1829. An eminent English watchmaker who invented the spring detent escapement and the compensation balance, both essentially the same as are now used in chronometers. He first soldered brass and steel together for the balance instead of riveting them.

EAST, EDWARD—Watchmaker to Charles I and an eminent horologist. He was one of the ten original assistants named in the charter of the Clockmakers' Company and at once took a leading part in their proceedings. He was elected master in 1664 and 1682. He was the only treasurer ever appointed by that company. He died probably about 1693. East's watches were often presented as prizes by Charles in tennis tournaments.

EDWARD VI—King of England from 1546 to 1553. Said to have been the first Englishman to wear a watch.

ELECTRIC CLOCK—A clock in which the pallets moved electrically from a distant mechanism drive the escape wheel and the hands.

ECLIPTIC—That plane passing through the center of the sun in which lies the orbit of the earth. Also used to designate the apparent path of the sun in the heavens.

ELGIN—A city in Illinois, U. S. A., in which is located the Elgin National Watch Company—one of the largest factories in the United States.

END-SHAKE—Freedom of pivots to move endways. Necessary in a watch or clock because there is no force to spare and a tight pivot would stop the movement.

END-STONE—A small disc of jewel against which the end of a pivot sets. See _Capped Jewel_.

END-STOP—In a watch the same as end-stone.