Time & Clocks Dictionary
Rack Clock: A GRAVITY CLOCK in which the whole clock slowly slides down a toothed rack on a stand. A PINION in the clock is driven by engaging the rack.
Rack Lever: A transitional LEVER ESCAPEMENT before MUDGE'S detached lever. Invented by the Abbe d'Hautefeuille in 1722. Many were made in England by Peter Litherland, Roskell, and others, of Liverpool, after 1791.
Rack Striking: Method of 'counting', i.e. controlling strikes of a clock, invented by BARLOW in 1676 and now universal. At the hour, a toothed arm (the rack) drops on to a cam and is wound back a number of teeth equal to the strokes. The cam, which is snail shaped, turns with the hour hand, therefore striking cannot get out of sequence as with the LOCKING PLATE used formerly. It may be damaged by turning hands backwards in older clocks; in modern ones there is provision for avoiding damage.
Radio Time Signal: The first were from the Eiffel Tower, Paris, and Nordeich, Germany, in 1914. The Greenwich time signal began in 1923 along a wire from GREENWICH OBSERVATORY to the B.B.C. Savoy Hill Studio, but is now from the time department of the Observatory at Abinger Common, Surrey, to B.B.C. headquarters (see Six Pips). Signals are corrected for land line delay. 'BIG BEN'S' first stroke at the hour was also used from 31 December 1923. Continuous time signals or frequency standards monitored by the ATOMIC CLOCK are broadcast from the Post Office radio station at Rugby (MSF), the U.S. Bureau of Standards (WWV), and transmitters in Switzerland (HBN), Italy (IBF), and Czechoslovakia (OMA). See Time Signal.
Railway Time: When railways spread over the country in the nineteenth century, they had to keep their own MEAN TIME because places through which they passed used LOCAL TIMES. They issued leaflets giving conversion figures from local times to Railway Time. Eventually both became GREENWICH MEAN TIME.
Raingo, M.: French maker of fine ORRERY clocks in the nineteenth century. Five are in England at Windsor in the ROYAL COLLECTION; in Soane's Museum, London; the Glasgow Art Gallery; and private collections-one is in the Paul Chamberlain Collection, U.S.A., and others in Paris, Madrid and Brussels.
Ramsay, David (d. about 1654): Chief clockmaker to King James I. Probably came from Dalhousie, Scotland. In the VICTORIA AND ALBERT MUSEUM are a watch and clock by him. He appears with a shop near Temple Bar in Sir Walter Scott's novel The Fortunes of Nigel.
Rate: The regularity of going of a clock or watch, regardless of how much is gaining or losing. A watch that gains, say, exactly three seconds every day has a perfect rate. One that gains a few seconds one day and loses some the next has a bad rate although it frequently shows the correct time of day.
Rate Recorder: Machine also called a 'timing machine', for printing the instantaneous RATE of a watch or clock. It comprises a QUARTZ CLOCK which controls the feed of a paper tape. The ticks of the TIMEPIECE are amplified and printed on the tape to produce a dotted line. The slope of the line gives the exact rate of the timepiece in a few seconds. Used for bringing to MEAN TIME arid for checking POSITIONAL ERRORS: also for fault finding, since OUT OF BEAT, MAGNETIZED, and other conditions are shown at once. Without a machine, each daily check takes 24 hours.
Rating Certificate: There are two main classes of testing. Tests for special timekeepers are carried out at the NATIONAL PHYSICAL LABORATORY, England; Geneva Observatory, Switzerland; and German Hydrographic Institute, and special certificates issued. Swiss production watches of high performance are sold with rating certificates issued by one of the Official Bureaux for testing watches. Only those gaining certificates can by law be called 'CHRONOMETERS'. These tests are for 15 days in five positions and different temperatures. The French have a scheme covering QUALITY STANDARDS as well as timing tests and watches are marked with stars according to results. The Swiss, Japanese and Russian industries also have general quality standards.
Rating Nut: Nut below a pendulum BOB for screwing it up or down to alter the clock's rate. On SECONDS PENDULUMS, a -& in. Whitworth thread makes one minute a day difference for one turn of the nut.
Raw Movement: Another name for an EBAUCHE.
Recoil Escapement: Another name for the ANCHOR ESCAPEMENT because the wheels turn back a little after every jump forward. This 'recoil' can be seen by watching the seconds hand of a LONG CASE CLOCK.
Recoiling Click: A form of STOP WORK applied particularly to watches to prevent their being overwound. In the simplest version, the click (ratchet pawl) which holds up the MAINSPRING has a slot instead of a hole for its bearing. Thus when a watch is wound up as far as it will go, the click will recoil and let down the spring a little as soon as the winding button is released . There are many other versions.
'Record' Tompion: Magnificent LONG CASE CLOCK made about 1699 for King William III by Thos. TOMPION, probably for Hampton Court Palace. It has a fine case with gilded mounts and a figure of Minerva on the top. The plinth base is of cast and chased metal, the only other Tompion clock with this being in Buckingham Palace. The clock runs for three months at a winding arid has a PERPETUAL CALENDAR. Given by Queen Victoria to the Duke of Cambridge, it was sold at Christies in 1904 for 125 guineas, reappeared in the Dunn Collection and sold in 1911 for 380 guineas, appeared in the WETHERFIELD COLLECTION arid sold in 1928 across the Atlantic; then bought back by an English collector, J. S. Sykes, for £4,000. In 1956 it was sold again to the U.S.A., when Williamsburg, Virginia, bought it for £11,000, despite attempts to stop the sale, because of the clock's historic value. The origin of the name 'Record' is not known.
Registered Horological Retailer: Watch and clock retailers who are members of the BRITISH HOROLOGICAL INSTITUTE arid agree to abide by certain high standard of trading are issued with special plaques which customers should look out for as it gives them protection against unfair salesmanship.
Registered Watchmaker: The BRITISH HOROLOGICAL INSTITUTE keeps an illuminated record of craftsmen who have qualified by examination and have had so many years' experience. They are allowed to show a special plaque. To protect themselves, the public should always go to one of these watch repairers. In the U.S.A. and Canada, watchmakers are registered in some states which insist upon certain minimum qualifications.
Regulation: Adjusting the RATE of a timepiece. Precision of regulation depends on the design, quality, and condition of the timepiece. Accurate regulation of a clock is much easier than of a watch because it is normally stationary. Every watch goes at different rates in different positions and has to be regulated to average the errors. Also it will go about 10 sec. a day slower in wear and has to be adjusted to suit the wearer if a high-grade watch. To speed adjustment, watchmakers use RATE RECORDERS. In the factory or after major repair the BALANCE 1S POISED, and HAIRSPRING timed, and the assembly 'timed' by rate recorder before being mounted in the watch; then the outer end of the hairspring is 'pinned up' and the assembly SET IN BEAT. Next, adjustments are made t0 reduce POSITIONAL ERRORS as much as possible. In wrist-watches the worst errors are left in the unimportant 'winding button right' position (as when the watch is worn on the inside of the left wrist). The watch should now have a good rate so that final regulation to bring it to MEAN TIME can be done by moving the INDEX. High-grade watches are sometimes FREE SPRUNG which means they have no index, being regulated by TIMING SCREWS or nuts on the balance wheel. A clock with balance and spring is regulated similarly except that positional errors are not now important. A PENDULUM clock is regulated by moving the BOB up or down by a RATING NUT. Precision pendulum clocks have a tray part way down the pendulum rod on which small weights can be placed to raise the effective height of the bob and make the clock gain, a halfpenny on the tray of 'BIG BEN' for 24 hr., making it gain b sec. Very early clocks were regulated by moving the weights on the FOLIOT in or out, and, if they had balance wheels without springs, by BRISTLE REGULATOR and by SETTING UP the MAINSPRING or altering the driving weight. Early watch balances with hairsprings had a REGULATOR (turned by a key which moved a toothed wheel) to adjust the hairspring length. See Temperature Error, Barometric Error, Circular Error, Isochronism, Tourbillon.
Regulator: Very accurate LONG CASE CLOCK usually with DEAD BEAT, PIN WHEEL Or GRAVITY ESCAPEMENT, TEMPERATURE COMPENSATED pendulum and no striking or other complication. The dial usually has three separate CHAPTER RINGS for the long central minute hand, the shorter hour hand below it, and seconds hand above it. The case is usually plain.
Regulator, Clock: See Rise and Fall Regulator and Regulation.
Regulator, Watch: Device for regulating the timekeeping of a watch. Before the HAIRSPRING was invented this was done by SETTING-UP the MAINSPRING by a ratchet and dial provided, and by BRISTLE REGULATOR. The first to adjust the effective length of the hairspring was TOMPION in the 1660s. A dial on the back of the MOVEMENT was turned by a key. The dial was geared to a segment carrying CURB PINS between which ran the end of the hairspring. This idea persisted until nearly 1800. About the same time, BARROW employed a threaded rod which moved a nut carrying curb pins, but it did not become popular. On the Continent Tompion's scheme was favoured except for the use of a moving pointer and fixed dial. The next development was a movable ring, carrying curb pins and a pointer, fitted round the hairspring. This developed into the INDEX on the BALANCE COCK, a pointer fitted friction tight round the JEWEL or SHOCK ABSORBER, which carried the curb pins. It is used on modern watches, and has been developed into the auxiliary regulator or index, which has an additional friction ring carrying the index pins, so that after the watch is adjusted by the factory the index pointer can be set to a central position.
Remembrance Watch: A watch in which the numerals 1 to 12 are replaced by the letters of a person's name, or a message.
Remontoire: Device which applies a controlled force to IMPULSE the PENDULUM Or BALANCE to overcome variations in timekeeping caused particularly by variations in the driving motor. One way is to wind up a small weight (invented by HUYGENS in 1659). Another keeps 'reloading' a small spring. John HARRISON used this in 1739. The modern Secticon battery clock has a spring remontoire. The GRAVITY ESCAPEMENT arid the GRAVITY ARM Of an ELECTRONIC MASTER CLOCK are both forms of remontoire. Also called a 'constant force escapement'.
Repeater Alarm: A modern alarm clock that rings in short bursts with an interval of about half a minute between them. A SYNCHRONOUS version allows the sleeper ten minutes 'dozing time'.
Repeater Clock: Before the days of artificial light, it was difficult to read a clock at night without the performance of lighting a candle with flint and tinder. Some of the best BRACKET CLOCKS could therefore be made to repeat the time on bells. Usually there is a cord with a button on the end from each side of the clock which is pulled to load and operate the REPEATING WORK. This is called a 'pull repeater'. Most clocks are QUARTER REPEATERS, invented by Edward BARLOW in 1676; some are HALF-QUARTER REPEATERS, arid a few FIVE MINUTE REPEATERS. MINUTE REPEATERS are known from the eighteenth century. The repeater clock went out of fashion when matches were invented in the first quarter of the nineteenth century.
Repeater Watch: A pocket watch which will repeat the time on a bell, GONG, or the watch case itself. Intended mainly for use in the dark. The first, QUARTER REPEATERS, were invented by Edward BARLOW and Daniel QUARE near the end of the seventeenth century. BREGUET employed wire gongs in 1789. Other types are MINUTE (introduced in the nineteenth century), HALF QUARTER, and FIVE MINUTE REPEATER. There is no special winding button for the repeating work; on earlier watches the PENDANT of the watch is pressed and on later ones a slide on the side of the case is moved (which loads a spring) and when released sets the REPEATER going. See Dumb Repeater.
Repeating Work: A form of COMPLICATED WORK enabling a REPEATER CLOCK Or WATCH to strike the time at will. In watches this is complex and involves separate RACKS for repeating the hours, quarters, half quarters, five minutes, and minutes. See Barlow.
Repousse: Embossed designs, usually on silver or gold, most popular for watch cases in mid-eighteenth century.
Republican Time: Attempted decimal division of the hour into 100 minutes by the French Revolutionaries. See Decimal Clock.
Revolving Band Clock: Clocks in which a band marked with 12 or 24 hours revolves to indicate the time against a fixed pointer. Popular in France in the eighteenth century and used on clock cases shaped like urns, vases, and globes.
Riefler Clock: Precision PENDULUM clock with TEMPERATURE COMPENSATION, invented by Riefler of Munich in 1889 and adopted as an OBSERVATORY CLOCK. The PENDULUM is almost FREE. It is IMPULSED by an arrangement that flexes the SUSPENSION SPRING of the pendulum first one way then the other. See Accuracy of Clocks and Mercurial Pendulum.
Ring Watch: A watch mounted in a finger ring. Guido Ubaldo della Rovere, Duke of Urbino, is recorded as having had a CLOCK WATCH so mounted in 1542! A very small ring watch with 120 parts was made in 1764 for King George III. The MOVEMENT was only 1/3 in. across. It had a CYLINDER ESCAPEMENT with a ruby cylinder, the first known, only 1/54 in. in diameter, and was a HALF-QUARTER REPEATER. It probably still exists although its present whereabouts are not known. Modern ring watches are made in quantity.
Rise and Fall Regulator: Early arrangement for adjusting the length of a PENDULUM from the top, by moving the SUSPENSION SPRING in a slot. Alternative to screwing the bob of a PENDULUM up or down for timekeeping REGULATION.
Rock Crystal: Transparent quartz used for decoration, 'glasses', CASES, and even PLATES, of clocks and watches from the earliest days.
Rolled Gold: Thin layer of gold which has been soldered to a base metal such as nickel and rolled out thinner. A British Standard of 1960 requires rolled gold watch cases to be marked 'R' followed by the thickness of gold in microns (thousandths of a millimetre) thus: R 20 M. Cases used to be stamped with the number 5, 10, 15 or 20 according to how many years the rolled gold was expected to last.
Rolling Ball Clock: See Ball Clock.
Rolling Clock: Form of GRAVITY CLOCK (without mainspring). The earliest still existing was made about 1600 by Isaac HABRECHT. The clock is drum-shaped and rolls slowly down an inclined board. The hand remains still and hour numerals turn with the case. Still made by Gubelin in Switzerland and Garrard in England, but the dial remains stationary and the hands turn normally. When the clock reaches the bottom of the inclined plane it is replaced at the top by hand. The inclined track is often marked with days of the week.
Roman Numerals: These still persist on clock dials because of their symmetry, which is why IIII is usually used (to balance the VIII) instead of IV. 'Big Ben' has IV.
Roman Striking: Method of striking by Roman numerals instead of Arabic, invented by Joseph KNIBB to reduce winding. A high-pitched bell represents 1, a low pitched one V, and two blows on the low pitched one, X. Thus IX is sounded by a highpitched note followed by two low ones.
Roscopf: First cheap watch, a pocket watch made in 1865-67 by G. F. Roscopf, a German who settled in Switzerland. He eliminated the CENTRE WHEEL, which allowed him to use a big BARREL overlapping the centre of the watch. The ESCAPEMENT was a separate PIN-PALLET unit; the winding button could be turned only one way; there was no STOP WORK; the MOTION WORK turned on the barrel ARBOR; and the hands were set by turning them with one's finger. The 'people's watch' was steadily improved until today many millions of cheap wristwatches are made on a modified Roscopf lay-out, in all watchmaking countries except, strangely, U.S.S.R., which makes only JEWELLED LEVERS.
Roskilde Cathedral Clock: Early Danish 24-hour clock in Roskilde, with two jacks and St George slaying the dragon, which utters agonized cries!
Rotor: Eccentric weight which winds the MAINSPRING of a SELF-WINDING WATCH, and can turn through a full circle, as opposed to the PEDOMETER WATCH weight, which has a limited swing. Many rotors wind the watch while turning either way.
Royal Clockmaker: In earlier days of clockmaking in any country, appointment to the Court meant good business, and many famous makers held such positions. Nicholas CRATZER, clockmaker to Henry VIII in 1538, was the earliest known in England. One of the most versatile was Peter Auguste Caron, who made watches for the French King, invented a VIRGULE ESCAPEMENT in 1753, and was a musician and author, writing The. Marriage of Figaro and The Barber of Seville under the name or 'Beaumarchais'. The appointment is still made in Britain, but to a retailer. There were sometimes separate appointments of Royal Watchmaker, but earlier makers produced both watches and clocks.
Royal Collection: This contains many magnificent clocks, most of which are in use in Windsor Castle, Buckingham Palace, St James's Palace, and Hampton Court. They include the ANNE BOLEYN CLOCK; an early Augsburg MUSICAL CLOCK by Jacob Mayr; ASTRONOMICAL CLOCKS by Juhen LE ROY, RAINGO, PINCHBECK, Lepine, and Eardley Norton, whose version has four dials, one on each side. There are many fine French clocks, some with fine BUHL cases, including a SYMPATHETIC CLOCK, REGULATOR, and a two-pendulum (one for metronome use) clock by BREGUET and a YEAR CLOCK by Lepaute. Other clocks are by TOMPION (one has a 24-hr. dial and shows both EQUAL TIME and APPARENT TIME); QUARE (year clock); Isaac Duhamel; John Barwise; Richard Vick; Alex Cumming (month clock); and VULLIAMY. There are SKELETON CLOCKS designed by CONGREVE, a Negress head clock with hours and minutes in the eyes by Lepine and even a TAVERN CLOCK (at Windsor Castle).
Royal Greenwich Observatory: The English national observatory which was set up by the Admiralty in 1676, with John FLAMSTEED as its first ASTRONOMER ROYAL. His duty was to make star observations to assist navigation of ships, the problem of FINDING THE LONGITUDE, which was eventually solved by the MARINE CHRONOMETER. The Observatory eventually became responsible for TIME DETERMINATION and TIME DISTRIBUTION, and the maintenance of the Admiralty's MARINE CHRONOMETERS, etc., while continuing its astronomical work. In 1946 a move was made to Herstmonceux Castle in Sussex because the industrial haze over GREENWICH OBSERVATORY interfered with observations, but the name was not changed. See also Airy, Observatory Clock, Octagon Room, Prime Meridian and Time Ball.
Royal Pendulum: Contemporary eighteenth-century name for the SECONDS PENDULUM.
Ruby Pin: The pin made of synthetic ruby through which the lever of a LEVER ESCAPEMENT gives IMPULSE to the BALANCE. Also called 'impulse pin'. In PIN-PALLET escapements it is often of steel.
Russian Horological Industry: In 1929 the Soviet Government started an industry by buying two complete American watch factories, the Duber Watch Co. and the Ansonia Watch Co., to set up the First and Second Moscow Watchmaking Plants respectively, which were extended and reconstructed in 1934-35, when two extra plants were set up in Kuibyshev and Prenza. During the Great Patriotic War (Second World War) watchmaking plants were set up in the East at Christopol, Chelyabinsk, Zlatoust, and Serdobsk, then mainly for fuse making, and after the war others at Oryol, Yerevan, Minsk, Rostov-onDon, Petrodvorets, Uglich, and elsewhere. Only JEWELLED LEVER watches are made in Russia. Clocks include all types. The industry has the world's biggest output after Switzerland. Technical control of the whole industry is under a single organization in Moscow. Yearly watch output is about 17% of world output but rising rapidly.
Rye Church Clock: Oldest English clock still working in its original place, in Sussex. Made in 1515 and later converted to 2 1/4 sec. approx. pendulum, which hangs down inside the church.