Time & Clocks Dictionary
Galileo: Pioneer of experimental science who discovered that a PENDULUM kept the same time however widely it swung (but see Huygens). Invented an excellent PENDULUM-controlled ESCAPEMENT, before Huygens, but it was kept secret and constructed by his son after his death too late to influence horology.
Gas Controller: The first form of TIME SWITCH. Invented by Dr Thurgar, of Norwich, in 1867, for turning gas street lamps on and off. The first practical use of them, however, was made by a Bournemouth builder, John Gunning, for street lighting as he could not sell houses in unlit streets.
German Horological Industry: Many of the oldest clocks and watches known are German and early centres were NUREMBERG and Augsburg. An industry making WOODEN CLOCKS also grew up in the Black Forest, which popularized the CUCKOO CLOCK, but American competition nearly ruined it until Erhard Junghans re-established it on Swiss lines after 1851. Up to the Hitler war, it had one of the world's biggest outputs of clocks and watches. One main manufacturing centre for jewellery and watches, Pforzheim, was blotted out by the Royal Air Force because of the fuse making there, but has since been rebuilt, with many modern watch factories. Watch cases are also made in quantity there. The Black Forest is still the centre of a big clockmaking industry. The Germans have pioneered MAGNETIC SUSPENSION arid BATTERY CLOCKS.
Gilding: Gold finish for brass used on clock and watch dials and cases. Fire gilding (also called water gilding) was done by mixing gold powder with mercury to make a paste like butter which was brushed on. The brass was washed, next heated over charcoal, and brushed, being then left matt, or alternatively polished and burnished (see Frosting). The process is dangerous to health and is rarely done now although it is the only way to restore, say, French gilt work. Electro-gilding is extensively used today for various watch parts. 'Silver gilt' is sterling silver that has had a gilding treatment.
Glass: The watch glass appeared in the eighteenth century, although some dials were protected earlier by faceted rock crystal. In our century almost a11 'glasses' are unbreakable, i.e. they are plastics (such as Perspex or Plexiglas) and known to the trade as 'U/Bs', but also called 'crystals'. Transparent synthetic sapphire, often faceted on the edge, is used for some high quality small watches, as it does not become scratched. Normal glasses and U/Bs are 'sprung in' from the front, using a special tool to dome them and reduce the diameter temporarily. In WATERPROOF watches extra sealing or pressure rings are often employed with the glass,
Glass Bell: Used on early CUCKOO CLOCKS. One of the last made was the case as well as the bell of a special clock with SHIP'S BELL STRIKING produced for the Festival of Britain.
Globe Clock: Another name for a BALL CLOCK, but usually representing the Earth.
Gnomon: The rod, pin, or wedge-shaped plate of a SUNDIAL that throws a shadow on the dial. Also called a 'style'.
Going Barrel: The most common spring motor for watches and clocks. The going BARREL contains the MAINSPRING. The outer end of the mainspring is hooked inside the barrel, and the inner end is hooked to the BARREL ARBOR (i.e. the shaft through the barrel). The winding button or key turns this arbor, which winds up the spring. As the spring uncoils, it turns the barrel which has teeth round it to drive the gears. The barrel turns in the same direction as winding, and also provides its own MAINTAINING POWER.
Going Train: The TRAIN of gears in a timekeeper controlled by the ESCAPEMENT arid responsible for its timekeeping.
Gold Filled: In the U.S.A. this means the best quality ROLLED GOLD. In Britain the term is disapproved of by the British Standard for watch case finishes, because it is misleading.
Gold Plated: Covering of pure or alloy gold applied by an electro-chemical method. A British Standard of 1960 requires gold-plated watch cases to be marked 'P/' followed by the thickness of gold in microns (thousandths of a millimetre), thus P 15 M. See Rolled Gold and Hard Gold Plating.
Gold Watch: Watch in a gold case, used because it is unaffected by acids from the skin and corrosion, as also are platinum, ROLLED GOLD, GOLD PLATE, arid STAINLESS STEEL. Silver was once commonly used for watch cases, partly for the same reason. Goldsmiths have been associated with watchmaking for 400 years.
Golden Number: New and full moons return on the same days every 19 years. The year of this cycle is calculated automatically by some early clocks. The Greeks thought so much of the calculation that they had the number written in gold. Also called the 'Metonic Cycle'.
Golf Watch: Not a watch, but a recorder that looks like one. After each stroke, the golfer pushes the 'winding button' and after each hole gives it a twist. Strokes for each hole are shown in 18 apertures around the dial. The 'minute hand' shows the number of the hole and the 'hour and seconds hands' the running total.
Gong: Metal rod, either straight or spiral, on which chimes or hours are struck. Made of steel or phosphor bronze. May have been invented by Julien LE Roy. Straight ones are used in most domestic striking and chiming clocks, but early American wall clocks and French CARRIAGE CLOCKS have spiral ones, and REPEATER WATCHES curved ones made of steel.
Gothic Clock: In the sixteenth century HOUSE CLOCKS had open iron frames of Gothic style.
Gould, R. T. (1890-1949): Lieutenant-Commander Gould, R.N., author and broadcaster, was an authority on the MARINE CHRONOMETER (on which he wrote the standard book), typewriters, and the Loch Ness monster.
Graham, George (c. 1673-1751): One of the greatest of all makers of clocks, watches, and scientific instruments. Friend of, relation by marriage, and successor to TOMPION Invented the practical CYLINDER ESCAPEMENT for watches in 1725, the DEAD BEAT ESCAPEMENT for clocks in 1715, arid MERCURIAL COMPENSATION for pendulums in 1721. Made nearly 3,000 watches, about 175 clocks, and various astronomical instruments. He was known as 'Honest George Graham'. Buried in Westminster Abbey with Tompion.
Grand-Daughter Clock: Modern clock of grandfather style standing under about 4 ft. 6 in. high.
Grande Sonnerie: Clock or watch which strikes the hour before chiming each quarter of an hour, e.g. at 3.30 it would strike three, then two quarters.
Grandfather Clock: Name for a LONG CASE CLOCK which originated from a song written by the American Henry Clay Work in 1876, beginning, 'My grandfather's clock was too tall for the shelf . . .' The clock he wrote about is claimed to be that in the George Hotel, Piercebridge, North Yorkshire, but another claimant is a relative, Mrs Randolph Parker, for her clock in Granby, Massachusetts.
Grandmother Clock: Like a GRANDFATHER, but under about 6 ft. high. Antique ones are extremely rare.
Grasshopper Escapement: Accurate wooden ESCAPEMENT not needing oil, invented by John HARRISON, for his clocks and marine timekeepers. Modified and used later by VULLIAMY.
Gravity Arm: A small lever of certain weight, pivoted at one end, for giving IMPULSES to a PENDULUM. It is normally held horizontal and released to rest on a projection on the pendulum. After impulsing the pendulum, it is reset electrically or mechanically. See Master Clock and Gravity Escapement.
Gravity Clock: Clock driven by its own weight. Two early forms are the ROLLING (Plate 6) and the FALLING BALL CLOCK (Fig. 11). Another, made as early as 1600, is the RACK CLOCK. The Silent Keeless was one such clock; various versions have been produced in recent times.
Gravity Escapement: Accurate clock escapement in which the MAINSPRING Or driving weight lifts a small lever, which drops to give IMPULSE to the PENDULUM Or BALANCE, and is thus independent of the driving force. Invented by Thos. MUDGE and by Alex. Cumming around 1760-70, but not really successful until GRIMTHORPE'S version of about 1852 for 'BIG BEN'. Employed in most accurate TURRET CLOCKS, ELECTRIC MASTER CLOCKS, arid the FREE PENDULUM. See Gravity Arm.
Great Clock: Early name for a TOWER CLOCK. 'Great clockmaker' meant a maker of big clocks, not a famous maker.
Great Tom: The bell of a clockhouse built at Westminster after the Commonwealth, which was removed to St Paul's Cathedral by Sir Christopher Wren when the Westminster tower was pulled down in the eighteenth century. The present Great Tom is a replacement. The original one saved a soldier accused of being asleep on sentry duty at Windsor Castle from court-martial sentence. He said he heard the bell strike 13. Unlikely as this was, it proved to be true.
Great Wheel: The MAIN WHEEL Of a FUSEE clock or watch.
Greenwich Civil Time: After 1925, GREENWICH MEAN TIME was reckoned from midnight instead of noon. American astronomers called this 'Greenwich Civil Time', but the British continued with G.M.T. Now both call it UNIVERSAL TIME.
Greenwich Mean Time (G.M.T.): Mean SOLAR TIME at GREENWICH OBSERVATORY. Solar times vary across the country, e.g. when it is 12 noon at Greenwich it is 11.40 a.m. at Pembroke. In 1880, G.M.T. was established by law as official time all over Great Britain. In 1884, an international conference adopted the line of longitude through Greenwich as zero MERIDIAN and the basis of TIME ZONES (on the proposition of the U.S.A., only France and Ireland voting against).
Greenwich Observatory: Original building of the ROYAL GREENWICH OBSERVATORY which has been moved to Herstmonceux Castle, Sussex. The Greenwich building, including the OCTAGON ROOM, is now a museum of timekeeping and astronomical instruments. See National Maritime Museum Collection.
Gridiron Pendulum: A PENDULUM compensated for TEMPERATURE ERRORS, invented in 1726. A grid of alternate brass and steel rods is arranged so that in heat the expansion of one metal upwards is equal to the expansion of the other downwards, so that the pendulum remains the same length. See Compensation Pendulum.
Grimthorpe, Lord (E. B. Denison, M.A., Q.C.): The irascible lawyer and brilliant amateur clockmaker who designed 'Big Ben', the WESTMINSTER PALACE CLOCK, to which he applied his GRAVITY ESCAPEMENT, as well as other clocks. He upset clockmakers by leaving non-working parts rough, but 'Big Ben' proved not only bigger, but much more accurate than any clock previously made.
Grollier, Nicholas (1593-1686): Famous maker of ROLLING BALL CLOCKS in which the ball is the timekeeper. The invention of the practical PENDULUM clock virtually finished attempts to make the rolling ball an accurate time standard, but see Congreve Clock.
Guildhall Museum: London clock and watch collection and library of the CLOCKMAKERS COMPANY with many fine specimens including MARY QUEEN OF SCOTS WATCH and the HARRISON wooden precision clock.
Guillaume, Charles-Edouard (1861-1938): Director of the International Bureau of Weights and Measures, Paris, who won the Nobel Prize in 1920 for inventing INVAR and ELINVAR, which revolutionized precision timekeeping.
Guillaume Balance: A COMPENSATION BALANCE that overcomes MIDDLE TEMPERATURE ERROR by using a special nickel alloy (instead of steel) with brass for the bi-metallic rim of the CUT BALANCE. Introduced by GUILLAUME for use with a steel HAIRSPRING in 1899, but still today at the top in TIMEKEEPING TRIALS. Also called the 'integral balance'. Weaknesses are the spring's susceptibility to magnetism and the tendency of the cut arms of the balance to fly outwards on heavy balance wheels. See Compensation Balance and Ditisheim Balance.
Guinness Clock: Large public clock with AUTOMATA representing various zoo animals in Guinness advertising. Made for the Festival of Britain Gardens, Battersea, in 1951. Eight copies were constructed followed by a number of simplified versions.