Time & Clocks Dictionary
Babylonian Hours: Early system of time reckoning in Babylon. A day and night period was divided into a continuous series of 1 to 24 EQUAL HOURS, but they started at sunrise each day.
Baillie, G. H. (1883-1951): Historian who specialized in clocks and watches and compiled a list of 36,000 makers.
Bain Clock: One of the earliest electric clocks. Some, like grandfather clocks in appearance, still exist and work off ground batteries-coke and zinc buried in the ground-which require watering in dry weather. There is one in the BRITISH HOROLOGICAL INSTITUTE Museum. Alexander Bain, a Scot from Thurso, also invented SLAVE DIALS.
Balance: A controlling device for clocks and watches which, through the ESCAPEMENT, momentarily unlocks and re-locks the gears at short intervals to move the hands. IMPULSES from the escapement keep the balance swinging to and fro. The first was the FOLIOT, a bar with weights on the ends used on large clocks in the thirteenth century. In the fourteenth century for watches and smaller clocks, this became the DUMBELL and the BALANCE WHEEL.
Balance Wheel: A BALANCE for clocks or watches which is shaped like a wheel. The earliest were made of steel or brass and had one spoke, the swing sometimes being limited by the spoke knocking against a steel pin or a HOG'S BRISTLE. Balance wheels with two spokes (an arm) soon became universal. The HAIR water, like the displays on SUNG'S CLOCK, and the large and elaborate scenes still existing at Heilbronn. Early automata worked by mechanical clocks were called JACKS. Later, jousting knights, waterfalls, windmills, ships at sea, animals playing musical instruments, acrobats, etc., were worked by the clockwork and often associated with MUSICAL CLOCKS. A famous one was Bridge's Microcosm (now in the British Museum). James Cox was a renowned maker in the eighteenth century. Watches were also made with automata (occasionally of erotic scenes which were concealed until operated by a secret PUSH PIECE). One of the most recent large clocks with automaton is the GUINNESS CLOCK. The word 'automation' is derived from this. SPRING was added in the seventeenth century and the increasing timekeeping accuracy stimulated attempts at TEMPERATURE COMPENSATION, resulting in various forms Of CUT BALANCE, often with AUXILIARY COMPENSATION. The invention Of ELINVAR for the hairspring caused a return to the plain balance wheel made of beryllium alloy or nickel for almost all clocks and watches, but MARINE CHRONOMETERS still have cut balances except for one made in the U.S.A. which has an OVALIZING BALANCE. Most modern balance wheels have a fifth of a second BEAT.
Balance and Spring: A BALANCE WHEEL combined with a spiral or cylindrical HAIRSPRING, which is the oscillating time standard in almost every watch and very large numbers of clocks. The two have to be considered together for purposes of TEMPERATURE COMPENSATION, REGULATION, etc.
Balance Cock: The COCK that holds the bearing, normally a SHOCK ABSORBER, for one end of the BALANCE.
Balance Spring: Alternative name for the HAIRSPRING.
Balance Staff: The shaft or axle of the BALANCE.
Ball Clock: This has three meanings. 1. A clock with a ballshaped case. Many versions have appeared from the eighteenth century to the present day. In some the ball has a REVOLVING BAND showing the hour and on others there is a normal dial with curved hands. One of the latter form made in quantity from about 1875 to 1925 had a sphere on the head of a bust of Atlas with a cupid on each side. Also FALLING BALL CLOCK. 2. A clock in which the driving power is provided by a heavy steel ball or balls moving down a, usually spiral, track. The balls are raised to the top of the track by a clockwork mechanism. The idea was to provide more even power than springs give and make the clock more compact than a weight driven one. It was employed by Nicholas Radeloff, a pupil of BURGI in the seventeenth century (Plate 3). 3. A rolling ball clock in which a ball running along a track is the timekeeping standard, instead of a PENDULUM or BALANCE. Developed particularly by GROLLIER and CONGREVE (Plate 6). See Congreve Clock and Tower of Babel Clock.
Ball Watch: Small modern ball-shaped watch, with the dial at the bottom, hung from a necklace or brooch. Reminiscent of the very first MUSK BALL WATCHES. See Watch.
Balloon Clock: Style of wooden case for a spring-driven clock, introduced about 1760. From the front it has roughly the outline of a Montgolfier balloon.
Band: Watch strap or BRACELET. See also Expanding Bracelet.
Banjo Clock: The case is similar to a banjo in shape. Invented by Simon Willard, U.S.A., about 1800, made in large numbers and particularly favoured by the railway companies as station timekeepers (and status symbols-the more important the station, the bigger the banjo).
Banking Pin: A pin or stop to prevent excessive motion of a BALANCE, HAIRSPRING, the lever of a LEVER ESCAPEMENT, a PENDULUM, GRAVITY ARM, etc. See Bristle Regulator.
Bar Movement: Early form of partly machine-made watch MOVEMENT in which bars, or BRIDGES and COCKS, are used to hold bearings for one PIVOT of each wheel, for easy dismantling.
Barlow, Edward (1636-1716): Clergyman who changed his name from Booth and became famous as a clockmaker by inventing RACK STRIKING, a form of REPEATING Work for clocks and watches, and also (with TOMPION and Wm. Houghton) an early form of the CYLINDER ESCAPEMENT.
Barograph Clock: A modern form of DRUM CLOCK used to drive the chart in a barograph.
Barometric Error: Changes in RATE caused by varying air pressure; in accurate pendulum clocks to the extent of 3/4 sec. a day per inch of mercury. Compensators worked by mercury and by aneroid barometers have been invented, but the modern method is to keep the pendulum in low-pressure air in a sealed chamber and to keep the air pressure and temperature constant. To reduce the error in free air, the pendulum BOB should be a cylinder as wide as it is high of the densest possible material, according to Colin Frye (1956). Few are, however. Watches are also affected. One modern wrist-watch is in a vacuum case.
Barrel: Drum-shaped container of watch or clock MAINSPRING. A GOING BARREL has teeth around it and drives the wheels (Plate 2). A spring barrel in conjunction with a FUSEE has no teeth and drives by winding a chain or gut line round itself. The drum round which the gut, rope or chain of a weight-driven clock is wound is also a barrel. So is the drum carrying pins or cams to operate hammers striking bells or a musical comb in MUSICAL CLOCKS and BOXES.
Basket Top: Pierced ornamental metalwork forming the domed top of a BRACKET CLOCK.
Bath Clock: Fine LONG CASE CLOCK in the Grand Pump Room at Bath, Somerset, given in 1709 by TOMPION. It is 9 ft. high in an oak case and also shows the EQUATION OF TIME. A sundial was supplied with it to check it, but has been lost.
Baton: A stroke used on a dial instead of a number.
Battery Clock: Mechanical clock with a special AUTOMATIC WINDING arrangement operated every few minutes by a torch battery which lasts for about a year. In one form, a small Swiss PRECISION CLOCK, however, the battery drives a continuously running electric motor driving a REMONTOIRE. Also a pendulum clock operated by a battery. See Eureka Clock, Bulle Clock, Electronic Clock, Thousand Day Clock.
Battery Watch: An ELECTRIC Or ELECTRONIC WATCH powered by a tiny battery, which lasts over a year. The Mallory battery is about I in. diameter and * in. thick. It has capacity of 80 milliamp-hours at 1.3 volts. An atomic battery for watches about the same size with lead screening to last about five years has been developed, and another Mallory battery of 140 milliamp-hours.
Beat: Watchmaker's name for 'tick'. A grandfather clock 'beats seconds' and a man's wrist-watch beats fifths of a second. Smaller watches are usually made to beat faster. Cheaper ones often beat slower. See Dead Beat.
Beat Plate: Another name for a DEGREE PLATE.
Beauvais Cathedral Clock: Large ASTRONOMICAL CLOCK with AUTOMATA, built in Beauvais, France, from 1857-66.
Bedpost Frame: Style of TOWER CLOCK made in the late eighteenth and nineteenth centuries with corner posts to the frame like Victorian bedposts with large knobs.
Bell Top: Top of a BRACKET CLOCK shaped like a church bell with concave sides (but rectangular, looking down on it).
Bench Key: Star-shaped clock key with ends to fit different WINDING SQUARES. Also key with adjustable end.
Berne Clock: Early public clock with AUTOMATA in a tower in Berne, Switzerland. Berthoud, Ferdinand (1729-1807) Swiss maker of very fine watches, clocks, and MARINE CHRONOMETERS, who was to have entered the Church but became a watchmaker in Paris at the age of 16. Invented a DETENT ESCAPEMENT, and wrote many technical papers. His nephew Louis Berthoud (1750-1813) also became famous for his chronometers.
Bezel: The rim, usually of metal, that holds the glass of a watch or clock.
Big Ben: Name given to the WESTMINSTER PALACE CLOCK, but actually the 13 1/2 ton bell on which it strikes the hours. The bell was cast in Whitechapel and hauled to Westminster on a trolley drawn by 16 horses. It was named after Sir Benjamin Hall, a large man who was Chief Commissioner in 1859. The first bell made weighed 14 tons and cracked badly when it was struck by its 8 cwt. hammer. When the present bell was hauled into place and struck, despite warnings by the clock designer Lord GRIMTHROPE to the architect that the structure was too weak, the vibrations thoroughly frightened everyone present and the mountings had to be strengthened immediately. The second Big Ben also cracked soon after it was installed, so the hour was struck on the next biggest bell, and Big Ben was not used for three years until 1862. Then it was given an eighth turn and has sounded ever since despite the crack. It can be heard four miles away. The B.B.C. first broadcast the sound of Big Ben on 31 December 1923, and soon after fixed a permanent microphone in the tower. The present hammer weighs 4 cwt. Striking can be controlled by hand and when the Monarch dies, his or her age is struck on 'Big Ben'. See Westminster Chimes.
Biggest Clock: The world's largest clock dial, 50 ft. across, is on the Colgate-Palmolive plant in Jersey City, U.S.A. (1924). The minute hand is 27 ft. 3 in. long. Britain's largest is the Singer Sewing Machine factory clock, Clydebank, Scotland, with four dials each 26 ft. across and minute hands 12 ft. 9 in. long.
Billiards Clock: Form of TIME SWITCH operated by the insertion of a coin so that it turns off the lights over a billiards table (or operates a mechanism to trap the balls in bar billiards) after a given time.
Bi-Metallic: Made of two different metals, each of which has a different rate of expansion when warmed. A bi-metallic strip of steel and brass riveted together, bends when heated or cooled. It was invented in the eighteenth century for the COMPENSATION CURB, and is today used in millions for thermostats. The bi-metallic BALANCE WHEEL rim was developed by EARNSHAW. All bi-metallic balances except the OVALISING one are CUT BALANCES.
Bi-Metallic Balance: A COMPENSATION BALANCE made Of steel and brass strip joined together so that they bend when heated to give TEMPERATURE COMPENSATION. Almost always a CUT BALANCE. On early timekeepers the strips were riveted together. BARNSHAW invented the method still used of fusing molten brass on to a steel disc and cutting the balance wheel from this. See illustration overleaf.
Bird Cage Clock: A cage with SINGING BIRDS in it which also has a clock dial on the bottom so that it can be seen when the cage is suspended. Made around 1780, probably of French and Swiss parts.
Bird Cage Frame: Spindly box-like frame of TOWER CLOCKS after about 1515. From about 1380-1515, these wrought-iron frames were massive, with corner standards like church buttresses. See Bedpost Frame.
Black Forest Clock: Type of clock made entirely of wood with VERGE and FOLIOT, and one hand. Strikes on a glass bell. First made there about 1680 by a carpenter Lorenz Frey of Spurzen St Margen, who copied a sample. Now, any clock from this area of Germany.
Blacksmith's Clock: The earliest big clocks were often made by blacksmiths, parts being forged and fire welded. Thos. TOMPION started his working life as a blacksmith.
Blacksmiths Company: Before the CLOCKMAKERS COMPANY was formed, the Worshipful Company of Blacksmiths had a monopoly of clockmaking. This led later to a strong feud between the two, long since settled.
Blind Man's Watch: Pocket or wrist-watch with knobs at the hours and sometimes a double one at 12, which can be opened so that the hand or hands can be felt. See Tact Watch. Modern versions include ALARM WATCHES.
Blinking Eye Clock: Another name for MOVING EYE CLOCK.
Bob: Weight on the end of a PENDULUM. Early BOB PENDULUMS had pear-shaped weights of brass. Others are usually cylindrical, or lenticular, i.e. disc shaped, and of brass, cast iron, lead encased in brass, zinc, or jars of mercury in the MERCURIAL PENDULUM. The RATE is unaffected by the weight of the bob, but see Barometric Error. Occasionally a novelty bob such as a model of a child on a swing or a fish on a line is used. In others the clock itself is the pendulum bob.
Bob Pendulum: The earliest form of PENDULUM, with a pear shaped brass weight (the bob) on the threaded end of a wire rod. The bob has a core of pear wood in which the wire formed a thread for adjustment of length.
Bolt and Shutter: A form of MAINTAINING POWER used on some fine quality LONG CASE CLOCKS. The winding hole is normally covered by a shutter; moving this aside by means of a lever in order to insert the KEY, applies power to the clock during winding so that its timekeeping is unaffected.
Bookmaker's Clock Bag: Special bag with a time lock used for betting slips collected by bookmaker's runners. The runner closes the bag which then locks and starts a watch in the lock. The jaws of the bag have 'teeth' which prevent slips being squeezed in after locking. The bookmaker can open the bag with a special key and note the time which has elapsed since it was closed.
Boulle Clock: Clock with a case of tortoiseshell inlaid with metal or ivory, or this inlaid with tortoiseshell. Perfected by Charles Andre Boulle (1642-1732). Also called 'Buhl'.
'Bounty' Watch: Duplicate of John HARRISON'S famous No. 4 watch made in 1772 by Larcum KENDALL and also known as 'K2'. It was loaned to Captain Bligh in 1787 for navigation of H.M.S. Bounty and taken by Fletcher Christian, leader of the mutineers, when Bligh was set adrift in an open boat. After the mutineers went to Pitcairn Island, Fletcher Christian sold it to a Captain Folger of the American whaler Topaz (some say to secure his passage from Pitcairn Island, for he disappeared afterwards). Folger was robbed of the watch by Spaniards at the 'Robinson Crusoe' island of Juan Fernandez. Somehow it reached a muleteer in Chile and passed through other hands until Captain Herbert of H.M.S. Calliope acquired it and brought it to England in 1843. It now belongs to the Royal United Service Institution, London.
Box Chronometer: A MARINE CHRONOMETER fixed in gimbals in a special box so that it will remain level. Some modern ones, and surveyors' chronometers, however, do not have gimbal fittings in the box.
Bracelet: Watch band or STRAP. Metal ones are usually of gold or are ROLLED GOLD, GOLD PLATED, STAINLESS STEEL Or a combination of them. Most are FLEXIBLE WATCH BANDS. Some are EXPANDING. Elaborate bracelets for ladies' watches are set with all kinds of gem stones and are classed among the finest jewellery.
Bracket Clock: Normal name for a wooden-cased clock commonly made in the seventeenth and eighteenth centuries for standing on a wall bracket or table. Usually fairly large and always portable, having a handle on the top. Often of ebony veneer with gilt metal ornaments. A more correct name would be 'table clock' or 'mantel clock'.
Braille Watch: A BLIND MAN'S WATCH. See also Tact Watch.
Brass: Alloy of copper and zinc introduced into clockmaking in the sixteenth century on the Continent of Europe, and adopted in England at the beginning of the seventeenth century. First used for cases and dials and later for PLATES, and WHEELS (early in the seventeenth century). ARBORS, PINIONS, and levers continued to be of iron or steel. The clockmaker cast his own brass and hardened it by hammering it. Brass and steel are still used, the brass being rolled and sometimes 'prinked' (like a lawn) to give extra hardness.
Break Arch: Shape of the top of clock cases or dials where the straight edge is broken by an arch which does not extend to the full width. See Arch Dial.
Breguet, A. L. (1747-1823): Considered by some the greatest watchmaker of all time, he was a Swiss who was taught at the Versailles watchmaking school (which was started by an Englishman). He then spent some years as a journeyman watchmaker, probably in London, setting up on his own in Paris in 1775 when he was immediately successful. His watches included perpetuals, which were and are highly prized, and SUBSCRIPTION. He invented a SHOCK ABSORBER known as the 'parachute' and the tourbillion. Many forgers tried to imitate Breguet's watches, so he used a SECRET SIGNATURE. During the French Revolution, he fled from his business at Quai de 1'Horloge on the Seine, Paris, to Le Locle, Switzerland, but he returned later. His work was of superb quality. See Marie Antoinette Watch and Oil.
Breguet Spring: An ordinary HAIRSPRING, whether spiral or CYLINDRICAL, moves out of centre as it opens and closes with the swinging of the BALANCE. This affects timekeeping as the spring is not isochronous. Isochronism can be greatly improved by curving the ends of a cylindrical spring in a special way towards the centre. Breguet discovered in about 1800 that the same effect could be obtained with a spiral spring by giving the outer coil an upward kink and curving it so that it was fixed near the centre of the balance. See Overcoil. It is somewhat difficult to use a REGULATOR on hairsprings with a 'Breguet overcoil' so they are usually FREE SPRUNG. The mathematical theory of terminal curves was later worked out by PHILLIPS and Lossier.
Bridge: A metal bar which carries one or more PIVOT bearings and is fixed at both ends.
Bristle Regulator: Before the HAIRSPRING was invented, the swing of the plain BALANCE was often limited in the sixteenth century by two stiff hog's bristles, which projected in the path of the arm of the balance and could be moved in and out from the centre to regulate the clock or watch. See Banking.
British Horological Industry: In 1368, King Edward III invited three Dutch horologiers to England to start clockmaking. During the seventeenth and eighteenth centuries under control of the CLOCKMAKERS COMPANY, it became the world's biggest, employing 70,000 craftsmen, who invented nearly all improvements to timekeeping so that even today no mechanical clock or watch is made anywhere in the world without a British invention in it. See Tompion, Graham, Harrison, Mudge, Barlow, Arnold, Earnshaw, Grimthorpe. The ENGLISH LEVER became the most desired watch of all. In the nineteenth century, Craftmakers in PRESCOT, COVENTRY and CLERKENWELL refused to accept changes brought about by factory manufacture and in a few years the industry was dead. Clockmaking continued, but was badly damaged when Hitler heavily subsidized the German industry in order to destroy the French and British industries,, upon which fuse-making depended, but MARINE CHRONOMETERS continued to be made. After the Second World War, the Government, having learned its lesson, re-established the watchmaking industry and encouraged clock manufacture, both on the most modern lines. Production now runs at about eight and a half million clocks and three million watches yearly. The main watchmaking centres are at Ystradgynlais, in South Wales; Cheltenham, Gloucestershire; and Scotland. All mechanical alarm clocks are made in three Scottish factories. Clocks are made around the London area and elsewhere, and industrial clocks of every possible type come from all parts of the country. TOWER CLOCKS are made in London, Middlesex, Derby, Leeds, Edinburgh, etc. There are still one or two makers by hand, and many ELECTRIC CLOCK makers.
British Horological Institute: Formed in 1858 to develop the science of horology and encourage high craftsmanship. Today it runs correspondence courses in technical horology, conducts national examinations, awards qualifications, controls apprenticeship, registers qualified repairers, runs exhibitions, and advises on national matters. Its President is the Astronomer Royal. At its headquarters in 35 Northampton Square, Clerkenwell, London, E.C.1, is a museum and the ILBERT LIBRARY. Its monthly Horological Journal is the world's oldest trade and technical journal. For their own protection, members of the public should deal only with B.H.I. REGISTERED CRAFTSMEN and retailers.
British Museum Collection: Includes the ILBERT COLLECTION, making it the world's most important, of 325 clocks and 1,360 watches and their movements, representing almost every invention or improvement in timekeeping, as well as artistic merit. Included are the Strasbourg tower clock of 1589; a table clock of 1580 by Bart. Newsum, clockmaker to Queen Elizabeth I; Thos.. TOMPION'S clock for GREENWICH OBSERVATORY; a magnificent MUSICAL CLOCK by Nicholas Vallin of London, 1598; one of the first LONG CASE CLOCKS, by A. FROMANTEEL; the 'Mulberry Tompion'; the original CONGREVE CLOCK; REGULATORS by GRAHAM and MUDGE: Mudge's first MARINE CHRONOMETER, and his first LEVER ESCAPEMENT clock; and many very interesting watches from the sixteenth to nineteenth century including fine ENAMELLED ones and examples by BREGUET.
'Britten': Casual name for a standard book on old clocks and watches first published in 1899 and written by F. J. Britten (d. 1913), secretary of the BRITISH HOROLOGICAL INSTITUTE for 33 years.
British Summer Time: GREENWICH MEAN TIME advanced by an hour in the U.K. during the summer, the dates being fixed by a Parliamentary Order yearly. See Daylight Saving.
Brocot Clock: A French clock with a PIN PALLET escapement of ANCHOR form combined with a pendulum invented by A. Brocot (d. 1878). Usually this escapement, with its semicircular agate PALLETS, is visible on the front of the dial and the clock case is of marble.
Buhl Clock: See Boulle Clock.
Bull, Randolph: One of the earliest English watchmakers. The BRITISH MUSEUM has a watch of his dated 1590.
Bulle Clock: Early BATTERY CLOCK invented by Favre-Bulle. The pendulum BOB is a coil of wire which swings over a fixed, curved, permanent magnet. A switch operated by the pendulum sends a current of electricity through the coil during a swing, making it an electro-magnet and thus IMPULSING it. The pendulum drives the hands by a pawl and ratchet mechanism.
Bull's-Eye Glass: The thick centre 'bull's-eye' of old crown glass, cut circular and used in the door of a LONG CASE CLOCK, to show that the pendulum was swinging. Most pendulum apertures were round or oval windows of ordinary glass.
Burgi, Jobst (1552-1632): Master clockmaker of Swiss origin, apprenticed to HABRECHT, and working at the Court of Kassel in a team with the astronomers Tycho Brahe, Kepler, and others. Inventor of t110 CROSS BEAT ESCAPEMENT. Several fine GLOBE CLOCKS by him exist in museums in Kassel, Vienna, the Louvre, Paris, and Gotha.