Time & Clocks Dictionary
Habrecht: Famous clockmaking brothers, Isaac and Josias, who completed the second STRASBOURG CLOCK in 1575. A fourfoot high clock made by Isaac in 1589 in imitation of the Strasbourg clock is in the BRITISH MUSEUM COLLECTION.
Hairspring: Also called 'balance spring'. A fine spring, usually spiral, applied to the BALANCE to make it much more accurate as a timekeeper. The invention was claimed by both HOOKE (in 1664) and HUYGENS (in 1675). At its inner end, the hairspring is fixed to the BALANCE STAFF by a small ring or 'collet' and a very tiny taper pin. At its outer end it is fixed to the BALANCE COCK by a stud. For simple timekeeping adjustments two CURB PINS are moved by the INDEX to alter the length of the active part of the hairspring (see Regulation and Regulator). Made of steel until ELINVAR arid the other temperature compensating and non-magnetic spring were invented (see Compensation Balance). Usually made now by winding four together as a 'nest' and separating them. CYLINDRICAL SPRINGS are also employed. The outer end is sometimes raised and curved towards the centre. See Breguet Spring, Free Spring and Balance and Spring.
Half Quarter Repeater: A REPEATER WATCH or CLOCK which, when operated, strikes the last hour on a lower note, the last quarter on a TING TANG, then either nothing or a higher note to indicate that 7 1/2 minutes (a half quarter) has passed since the last quarter. For example, at 3.38 there would be three strokes of the lower note, two ting-tangs on the two notes, and one stroke on the higher one.
Halifax Moon: Form Of MOON DIAL On which the phases of the moon are shown by a revolving globe coloured half black and half white.
Hallmark: Silver and gold watch and clock cases are assayed in Britain to determine the quality and stamped with: 1, the mark of the assaying 'hall'; 2, a quality mark; 3, the maker's mark, and 4, a date letter. The latter is useful for accurately dating antique watch cases. The Goldsmiths Company, London, marked gold cases from about 1685 and silver ones from about 1740. However, casemakers, although not members of the Goldsmiths Company, often struck their initials on cases from 1680 on.
Hammer, Striking: Hammer to strike a clock, bell, or GONG. Early ones were operated by AUTOMATA. The first for 'BIG BEN' weighed 8 cwt. and cracked the bell. Hammers of present domestic striking and chiming clocks have leather or plastic ends to improve the note. They are operated by a BARREL with cams or pins which press on the tails of the hammers to lift and release them.
Hampton Court Clock: Large ASTRONOMICAL CLOCK made c. 1540, at Hampton Court Palace, Middlesex.
Hand, Clock: Until about 1400 a clock had a rotating dial and a fixed hand. The first moving (hour) hands were like short arrows, with a pointed tail to make it easier to set them by hand. The arrow head on LANTERN CLOCKS later became heart shaped, then for LONG CASE CLOCKS it was pierced and elaborated. The minute hand came into general use after mid-seventeenth century and seconds hands became popular after 1660 when the long case clock came into use, the first of these having no tails. Both minute and seconds hands are, however, found on some very early special clocks (see Dondi's Clock). The finest hands were pierced and carved by hand and blued by heat, the hour and minute hands being considerably contrasted. Now clock hands are stamped out and coloured chemically, often having too little contrast between hour and minute. Hands of big public clocks were made of copper and bronze and are now often of aluminium alloy.
Hand, Watch: Before about 1700 watches had one thick hour hand, which was adjusted by pushing it. The accuracy of the HAIRSPRING encouraged the addition of a minute hand, and that of the CYLINDER ESCAPEMENT, a seconds hand. Early English hands were 'beetle' (like a stag-beetle) for the hour and 'poker' for the minute. French ones were often pierced. A modern fine steel or gold hand requires over 20 manufacturing operations.
Hanging Clock: Weight-driven clock that is hung from the wall, such as a LANTERN Or a HOODED CLOCK.
Hard Gold Plating: A method of plating watch cases with a gold alloy that can be hardened by heat treatment to make it more durable.
Harrison, John (1693-1776): Self-taught son of a carpenter from Foulby, Yorkshire, who, with his brother James, made extremely accurate clocks with wooden wheels (to avoid oiling). When the British Government offered a £20,000 prize for 'solving' or FINDING TIM LONGITUDE to help ships' navigation, he devoted the rest of his life to this, visiting London with his ideas, where GRAHAM lent him money. During the next six years he built his No. 1 timekeeper, which showed seconds, minutes, hours, and days, and worked very well on a sea voyage to Lisbon on test. Eventually his No. 4, a big watch, qualified for the prize by being only 15 seconds slow after five months at sea. The BOARD OF LONGITUDE refused to pay him fully and it was only after many years of dispute and the intervention of the King, that Parliament overruled the Board, and Harrison received the remaining money, at the age of 80! Invented GRIDIRON compensation, the GRASSHOPPER ESCAPEMENT, TEMPERATURE COMPENSATION, arid a form of MAINTAINING POWER. Worked in later years in Red Lion Square, London. Buried in Hampstead churchyard.
Hatton Garden: Traditional home of the diamond merchants in London and once the garden of Ely House. Now also a centre of much of the clock and watch trade, which moved from CLERKENWELL. Helical Spring Another name for a CYLINDRICAL SPRING.
Hemicyclium: Sundial shaped like quarter of a sphere and thought to have been invented by Berosus, the Chaldean astronomer, about 300 B.C. There is one at Pompeii.
Henlein, Peter: German clockmaker traditionally supposed to have invented the MAINSPRING for clocks and thus made the first portable clock or watch about 1510 (see Nurnberg Egg). It is more likely that the first watches were made in Italy before 1488.
Highest Church Clock: In England, this is in Limehouse Parish Church, with 200 steps to the clock room.
Hog's Bristle: See Bristle Regulator.
Hood: The top of a LONG CASE CLOCK case enclosing the MOVEMENT. The hood was lifted up for removal-and called a 'rising hood'-until about 1685, after which it was pulled forwards.
Hooded Clock: Transitional clock between the LANTERN arid the LONG CASE, the lantern clock being partly enclosed by a wooden HOOD, but still being hung on the wall.
Hooke, Robert (1635-1703): An eccentric genius, first experimenter of The Royal Society, horological inventor, and pioneer of the microscope. Discovered the law of springs (see Anagram). Invented various HAIRSPRINGS in 1664 which may have included a spiral one. In answer to HUYGENS claim, he declared 'Zulichem's spring not worth a farthing!' Designed a toothed wheel-cutting engine for clockmakers in 1670. Dr Hooke may have invented the ANCHOR ESCAPEMENT made by CLEMENT. Collaborated closely with TOMPION.
Hooke's Law: The law of springs discovered by Dr HOOKE which states that the force produced by a spring is proportional to its tension. See Anagram.
Horizontal Escapement: Alternative name for the CYLINDER ESCAPEMENT, because the ESCAPE WHEEL was parallel to the other wheels and not at right angles to them, as in the VERGE.
Horloge: Name given to both water and mechanical clocks in the Middle Ages, which makes it difficult to decide which is meant in ancient manuscripts.
Horology: The study of time and timekeeping.
Hour: Twenty-fourth part of a day, equivalent to 15° of rotation of the Earth. Hours were often of variable length (see Canonical Hours, Temporal Hours and Japanese Clock). The division of 24 may have come about as described under MINUTE. An hour is now based on the definition of one SECOND. The Italians were probably the first to use the 24-hour system (as opposed to two 12's) from the fourteenth century.
Hour-Glass: A SAND-GLASS arranged to time an hour's interval.
House Clock: Early name for a domestic or CHAMBER CLOCK, when there was usually only one in the home.
Huaud: Three Geneva painters, Pierre, Jean, and Amy Huaud became famous for ENAMELLED WATCHES, from about 1679.
Human Clock: Habits of all living organisms, including man, obey built-in 'clocks' with solar-daily, lunar-daily, monthly, and annual rhythms, e.g. the growth of a potato and the colour changes of a fiddler crab both have daily cycles depending on the moon. An interesting fact is that a human clock can be stopped (e.g. by freezing) and restarted, and can be reset, but cannot be speeded up or slowed down.
Hunter: Normally a pocket watch with a hinged lid over the face, but wrist-watches are occasionally made hunter style. A half-hunter has a hole in the centre of the lid to read the time -supposedly Napoleon's idea.
Huygens, Christiaan (1629-95): Dutch scientist who invented the first practical PENDULUM clock in 1657, which was made for him by Salomon Coster; discovered CIRCULAR ERROR; and wrote the first accurate treatise on the pendulum, HOROLOGIUM OSCILLATORIUM. Handsome and gifted man who was given an English title. Probable inventor of the spiral BALANCE SPRING, 1675 (but see Hooke). Often referred to as 'Zulichem'.