T

Table Clock :
The earliest domestic clock was the hanging iron Gothic clock, but the application of the mainspring led to its being redesigned to make it portable. The earliest spring clock movements resembled those of Gothic clocks; the most important changes in the design were the provision of a case to protect the wheels, the provision of a horizontal dial, and the introduction of the fusee connected to the spring barrel with a gut line. The movements of early table clocks were of iron; the cases were richly decorated with engraving, decorative castings, repoussé work and gilding. Some examples were provided with cases of precious metal, and for that reason many have been destroyed. Tablet :
The front, lower glass, frequently painted, on a clock case.

Tall Clock :
A long-case floor clock, often called a grandfather clock. Before 1775 the styles of the American longcase clock closely followed those current in England. Mahogany predominated from c. 1730 to c. 1840, with walnut used earlier and up to c. 1770. Cherry and maple became increasingly popular after 1775, particularly in provincial areas. The scroll top was fashionable in the United States c. 1770, the form and ornamentation being influenced by the progression of Chippendale, Hellplewhite and Sheraton styles of furniture designs. While many native-born craftsmen developed into successful clockmakers, the majority of brass movements with dials, hands, pendulums and weights were imported from England in the period up to 1820. Most were of the eight-day type, arranged for rack striking. Brass dials decreased in popularity from c. 1780 as the imported, Birmingham-enamelled, arched 'white dial' superceded them. Often these imported dials were signed on the face by local dealers. Although case designs closely followed English styles, ornamentation with carvings and inlaid decoration was uniquely American. The 30-hour tall-clock wooden movement which developed in Connecticut achieved importance in rural communities after c. 1790 and became common by 1810. This shorter case, usually 6 ft. 6 in. high, from less expensive pine or white wood and frequently grained to simulate mahogany, was made in thousands annually by local cabinetmakers in the period 1810-20. The numerous primitive styles reflect the country furniture of New Hampshire, Pennsylvania, Ohio, etc., where they were widely used until replaced by the Connecticut shelf clock during the early 1820s. The more sophisticated eight-day brass tall clock continued to be made in Boston, Massachusetts, and in areas of Portsmouth and Concord, New Hampshire, until c. 1840. The term 'grandfather clock' did not become general until after Henry C. Work's song 'My Grandfather's Clock', published in 1875, popularized the name.

Tambour Clock :
A shelf clock, also called a humpback or camelback clock, with a case that is rounded in the middle and gently slopes to flat sides.

Tavern Clock :
Another name for the large-dialled wall clock known as an Act of Parliament clock.

Telleruhr :
In the 17th century the pewter dish was a familiar household object. The shape must have suggested a clock dial, for in the 17th century clocks began to be made for hanging on the wall with dials in the shape of the normal domestic dish. The movements were light and usually provided with a cowtail pendulum that swung in front of the dial, allowing the clock to hang close against the wall. The movement was usually a timepiece only, without striking mechanism, and contained in a case of thin sheet-iron. The dish itself was of iron, covered with decoration in brass or copper relief. Sometimes the type was adapted to stand on a table and had small feet at the back, and later examples departed from the true dish shape. The German name for this type of clock is Telleruhr ('dish clock'). The type is found in south Germany and Austria but does not seem to have been popular in other countries.

Tellurium :
A mechanically operated model showing the revolution of the Earth around the sun, and of the moon around the Earth. An early example by Thomas Tompion and George Graham c. 1705 immediately preceded the famous orrery by John Rowley, which was itself a tellurium, the wood 'orrery' being now generally applied to later instruments showing the motions of the planets.

Têto de Poupée :
A French clock case of 'doll's-head' shape which evolved during the third quarter of the 17th century. The overall appearance of the clock is, in fact, of an oval head standing on a spreading moulded base, the top of the case being of segmental form and the sides deeply scrolled. In an elaborately decorated finish of Boulle work and applied gilded mounts, and often with an oval aperture embracing the dial, it survived until the Regency (1715-23).

Thirty-day Clock :
A clock that runs for a month on a single winding.

Thirty-hour Clock :
A clock which requires to be wound daily, with a margin of generally something over six hours to allow for a delay in rewinding. In particular, the name is associated with longcase clocks of 30-hour duration as opposed to eight-day clocks. Such 30-hour clocks are fitted with an endless rope or chain, the single weight driving both the going and striking trains; consequently, their dials have no winding holes. If they do show winding squares, they are dummy squares intended to suggest that the clock is an eight-day type. It should not, however, be thought that the eight-day type is necessarily superior to the 30-hour, for 18th-century examples of the latter occur in high-quality finish with fine brass dials. There are advantages in daily winding: the clock will probably be checked more frequently, and the endless chain system provides its own maintaining power.

Ticket Clock :
An American invention of 1903 utilizing the spring-like properties of then celluloid sheet. Two small circular drums bear a large number of small celluloid tickets free to pivot at the point of attachment on the periphery of the drums, and marked with numbers to indicate hours and minutes. Each ticket in turn is flexed against a pointer until released at the precise moment, upon which the ticket flicks over to display the opposite side, passing over a fixed index which then holds it in place to show the time. The drums holding the tickets are rotated by extended arbors from normal motion work powered by a small, spring-driven balance-wheel clock in the circular base; a glass tube surmounts this and is sealed by a metal circular top with a carrying handle. The visible metal parts are usually nickel plated, occasionally silver plated, and rarely gold plated. The clock was very popular in the United States and was later made in huge quantities in France and Germany. Alternative names for the ticket clock are Plato, digital, flick, flick-leaf and figure clock. In a different form the ticket display is used for the digital display of time in some modern electric clocks, for instance, the Caslon electrical digital clock made by the Copal Co.

Time and Strike (T & S) Clock :
A clock that both tells the time and strikes or chimes.

Time Measurement :
The presumed-unvarying flow of time is measurable differentially by observing a constant-rate process such as the movement of the sun's shadow on an equatorial sundial, or integratively by counting a series of evenly repeated events such as meridian transits of the sun (solar time) or of a star (sidereal time). For multiples of whole days, time has always been measured integratively, and the necessary counting of days and their multiples of weeks, months and years has been assisted by the use of tallies, diaries, calendars and historical records. Precision in differential time measurement of fractions of days was dependent first upon the development of accurate means of measuring the constant-rate apparent angular displacement of the sun and stars. The availability of alternative differential methods followed the discovery of such other constant-rate processes as flows of liquids under constant pressure. Precision in the use of these methods depended in the first instance on accurate measurements of length. The first use of an integrative method for measuring periods of time less than a whole day was probably the mental counting, or tallying, of the constant periods required for the repeated slow filling or emptying of a vessel full of water, or later sand. More general use of integrative methods was, however, dependent upon the eventual discovery of unvarying repetitive processes such as the vibrations of a foliot, spring-controlled balance, pendulum, tuning fork, quartz crystal, or atomic particle, and the development of mechanically or electrically operated apparatus for maintaining such processes.

Time Measuring Mechanisms :
All time measurements, whether by differential or integrative methods, originally required the attention of a watchman. The need for such attention only ceased when, besides automatic means of maintaining any artificial process involved in the measurement itself, automatic means of differentiation and/or integration had been developed. Automatic time measurement by a method combining differentiation and integration of time in a single mechanism was employed in early Chinese waterwheel clocks. Other methods of automatic differentiation were those of the Chinese and Arab water clocks in which an anaphoric-dial mechanism of the Greek type was made, by an axle-and-string arrangement, periodically to operate visible time signals and to release metal balls to operate audible signals. Automatic integration followed in some Chinese examples in which the metal balls also operated carousel jackwork. The Chinese waterwheel clocks also provided continuous integration of time over intervals longer than that required for a single rotation of the water wheel, by toothed wheelwork. With the development of weight-driven mechanical clocks, such wheelwork gradually came into general European use, but it is now being superceded by digital electronic integration in electronic clocks.

Time-annunciation :
For the best results of time measurements to be useful they had formerly to be announced by voice or other audible or visible signal. Parallel with the development of automatic time-measuring apparatus, there was thus a need for the development of automatic time annunciators. Audible signals have included bells, drums, gongs, rattles, musical wind instruments, guns and, latterly, electronically produced sounds, including voice recordings for use in telephone and radio systems. Audible signals were at first sounded personally by watchmen, and later by puppets called jacks, operated mechanically. For literate audiences such as those in early Chinese cities, watchmen also displayed written time announcements on banners or signboards. When jacks replaced the watchmen in the first Chinese astronomical clock towers, it was natural that by the horizontally rotating wheels of carousel jackwork the jacks should have been made to move horizontally across elevated stages like those previously used by the watchmen. The formerly widespread use of carousel jackwork for decorative purposes in European public clocks may owe its origin to this former practical function. Visible time announcements to the non-literate European public were at first possible only by the use of analogies such as a rotating statue whose hand pointed in the general direction of the sun, or an anaphoric dial carrying the sun's image behind a planispheric astrolabe rete. The European use of fixed dials with circumferential digit markings and rotating pointers, which were originally shaped like human hands, was a late development from the use of toothed wheelwork for time integration. Recently it has increasingly been replaced by written time announcements in digital displays operated mechanically, electrically or electronically.

Time-switch Clock :
Originally developed for switching shop-window display or street lighting on an automatic program. Similar clocks had earlier been used for controlling gas lamps by turning a gas cock instead of opening and closing electrical contacts. The use of time-switch clocks was greatly extended during the Second World War, when they were used for time-delay bombs, mines, etc. Nowadays they are incorporated in many devices for control of domestic heating, cooking ovens, lighting for intruder deterrence, process control, etc. An English firm, Horstmannn of Bath, have pioneered much of the work in this field. Later developments include the program clock which will carry out switching duties on a weekly basis, suppressing operations at weekends if required. Many millions of these clocks are in daily use throughout the world; the majority are electrically driven, spring reserve being fitted where a break in supply might result in disastrous disruption to the program.

Timepiece :
A clock that tells time only and does not strike or chime.

Tooth :
The shaped projections on a gear wheel which intermesh and transmit power are termed 'teeth'.

Torsion Clock :
The name is derived from the use of a torsion pendulum, which consists of a heavy bob suspended by a thin strip of metal or wire, having the property of combining a long period of vibration with a low energy requirement for maintenance of oscillation when the bob is rotated about the axis of the supporting wire. Robert Leslie of London patented a torsional pendulum in 1793 (patent no. 1970, dated 13 December). However, the torsion clock is generally attributed to the American Aaron D. Crane, who in 1829 and 1841 received patents for a single-ball torsion-pendulum weight-operated timepiece. This was made for eight-day, 30-day and one-year durations from a single winding and was produced in relatively small quantities, c. 1845, by the J. R. Mills Co., whose New York office was known as The Year Clock Co. In 1855 Crane was granted another patent for a torsion pendulum having 'two or more weights or balls', which was said to be temperature-compensated. After 1857 Crane moved to Boston where the one-year clock may have been made in limited quantities until his death in 1860. Silas Burnham Terry received a patent for a torsion balance in 1852, probably for a marine clock. This was adapted to a cheap 30-hour spring movement in either a miniature sharp Gothic or marine wall octagon case. The escapement was a conventional recoil attached to a thin ribbon placed in torsion through a cross-bar connecting rod, but the movement was only manufactured for a short period. Anton Harder in Germany appears to have devised his torsion pendulum clock independently c. 1879. It went for 400 days, but some models are only of one month duration. The final development of the torsion pendulum clock is the Atmos clock, deriving its power from temperature changes and therefore of unlimited duration. The earliest torsion pendulum clocks are very rare, but modern ones have been manufactured in hundreds of thousands.

Touch Pieces :
Small knobs or points found on medieval and early Renaissance single-handed clocks, for feeling the time in the dark. They were used for weight-driven clock dials and on spring-driven horizontal-dial drum clocks, both of which often had the Italian 24-hour notation. To distinguish the knobs that for XII was usually larger than the others. Their use declined after c. 1600, but the earliest watches of the 16th century were also fitted with touch pieces.

Tower or Turret Clock :
A church, steeple, or public clock in a tower.

TP :
An abbreviation for timepiece.

Train :
The series of gears and pinions that transfer power to the escapement.

Train, Eight-day :
The timekeeping trains of clocks are designed to go for a little longer than the period required between windings. A clock designed to be wound weekly will go for eight days before stopping. The usual eight-day longcase clock train consists of four wheels and three pinions. The great wheel carried by the barrel arbor drives the center pinion. The center arbor rotates once per hour and drives the minute hand and motion work through a friction spring, to allow adjustment of the hands. The center wheel drives the third-wheel pinion, which rotates once per minute. The 30-tooth escape wheel is mounted on this arbor, and an extension through the frontplate carries the seconds hand.

Train, Going :
The timekeeping train of a clock.

Train, Month :
Month-going clocks are usually arranged with an extra arbor carrying a wheel and pinion to give an additional 4 to 1 ratio between the great wheel and the center arbor.

Train, Seconds :
A clock train suitable for a seconds-beating pendulum or, alternatively, for driving a hand indicating seconds.

Train, Striking :
The gear train controlled by the striking mechanism of clock.

Train, 30-hour :
The 30-hour train has one wheel and pinion fewer than the eight-day clock. In the common 30-hour longcase train, the motion wheels are driven directly from the great-wheel arbor. Many 30-hour spring-driven trains are arranged to have the great wheel driving the center pinion, whereas in an eight-day going-barrel clock and intermediate wheel and pinion are used.

Train, Year :
The problem of providing sufficient power to drive the escapement with the very high gear ratios necessary to make a clock go for a whole year has been successfully overcome by only a few makers. The wheel work must be proportioned with due regard to its work in the train; the faster-moving wheels (and particularly the escapement) must be made very light so that inertial losses will be minimal; and tooth profiles and pivots must be designed to reduce frictional losses to a minimum. Weight-driven year clocks may be arranged by providing two extra wheels and pinions between the great wheel and the center pinion, which gives an additional ratio of 52 to 1 over that found in eight-day clocks. Spring-driven year clocks are usually found to contain a number of standard mainsprings, connected end to end, driving the great wheel; though a magnificent year clock driven by single springs and fusees was made by Thomas Tompion for King William III, between 1695 and 1700. The gear frictional losses are reduced by this layout, at the cost of a large number of turns being necessary to wind the clock annually.

Transit Instrument :
A telescope mounted in horizontal bearings lying in an east-west direction, so that if the telescope is at right angles to its axle or arbor it will always lie in the meridian plane. A vertical crosswire in the center of its eyepiece provides that when the image of a star lies exactly on this wire the star must lie exactly on the meridian, and is making its transit, the time of which can be recorded on a chronograph.

Travelling Clock :
A broad term for any clock made to be used when travelling. In the 17th century it usually took the form of an extremely large watch, but bracket clocks and even lantern clocks were made during the 17th and 18th centuries to accompany travellers. They were provided with stout wooden carrying cases, but if pendulum-controlled could not, of course, keep time during an actual journey. Thomas Tompion made at least two clocks which could be converted from pendulum to balance control for travelling; early domestic clocks were very expensive and it was often convenient to be able to carry one's own clock. The Capucine and pendule de voyage were the French ancestors of what is now known as the carriage clock which, with balance control, were made in enormous numbers in France during the 19th and early 20th centuries. They were fitted with carrying handles and protective outer cases in a style which was often copied in England and North America. The modern travelling clock, which is known as a calotte, unfolds from its case to stand on the hotel bedside table. Among early clocks it is important to distinguish between those which are travelling clocks (pendules de voyage) and those which have handles merely for moving about the house. (pendules portatives).

Triple-decker Shelf Clock :
A late 20th-century name given to a series of different Empire designs of American shelf case. They were introduced at Bristol, Connecticut, c. 1830 to market the eight-day weight strap brass movement with roller pinions developed by Joseph Ives, the original design having been conceived by Elias Ingraham. The features common to all designs consisted of an upper dial door with plain glass; a smaller lower door with a tablet or looking glass in front of the pendulum; and a glass panel between these two doors which extended the width of the case and contained either a looking glass or a painted tablet. Both doors were flanked by half-columns, veneered, stencilled, gilded, grained or carved. Each side ofthe middle glass was inset with a short whole column, generally turned and decorated to match the door half-columns. On top a splat was set between two short pilasters. Two types of feet were early additions; carved lion paws with the carved column and top cases; turned-ball types, frequently gilded, with the other cases. There were numerous modifications. This style of case continued until c. 1850.

Trumpeter Clock :
The cuckoo clock was well established in the Black Forest by the mid 19th century, but a new product was needed to capture new markets. Jakob Bäuerle in Furtwangen had the idea of using a current of air to sound a trumpet instead of the normal organ pipe of the cuckoo clock, and built the first trumpeter clock in 1857. The figure 'blowing' the trumpet was of a lookout man on the railway who blew his horn to warn men working on the track of an approaching train. The following year a model was produced that played a tune, with the figure in the form of a postilion, a soldier or a Tyrolese. The clocks were expensive, and not many were made; they never challenged the popularity of the cuckoo clock, which is still with us today. The center of manufacture was Furtwangen, and the clocks were made in decreasing numbers into the present century.

Tumbler :
See Pallet, Gathering.

Turkish Market :
During the 18th century a large trade was built up between Turkey and England. Turkish-market watches are more common than clocks; both had dials with Turkish numerals and often Turkish signatures on their movements. Turkish-market clocks were generally expensive articles, decorated with inlay, tortoiseshell and lacquer, with silver or gilded mounts and frequently incorporating musical work. The type is almost entirely confined to bracket clocks, their decoration being in the European taste except for the exclusion of human representations. A few makers specialized in this trade, notably Markwick Markham of London. The trade declined early in the 19th century.

Türmchenuhren :
A German expression meaning 'little tower clocks', applied to the form of table clock that has a vertical dial, in contrast to the horizontal dial of drum clocks. Tabernacle clocks come under this heading and also those clocks whose shape more directly suggests a tower, particularly the hexagonal type favored in 16th-century France.

Turret Clock :
Turret clocks are large, normally public clocks, housed in church towers, town halls, stable buildings and similar structures. A complete history of European turret-clock development over the centuries would be far too lengthy to attempt here, but eight notable clocks have been selected for detailed review.

Turret Clock #1 (Vor Frelsers Kirche, Copenhagen) :
This clock of monumental proportions, standing about 7 ft. from floor to top rail, bears the inscription, 'Johann Mercki Koppenhagen - Anno 1699'. It is of birdcage construction but like so many European clocks it has an additional pair of feet midway between the corner posts to support its great weight, and the corner posts continue downwards to form legs. Each leg has an outward set in it, forming a knee, and at the end the legs turn over to form feet. The frame bars are fastened by wedges. The striking and chiming trains are arranged end to end in the outer compartments of the clock, enabling the fly and count wheel of each to hang outside the frame at each end. The going train in the central compartment is at right angles to the other two. Lantern pinions engaging contrate wheels on the striking and chiming trains, and with a spur wheel on the going train, permit winding from the front. The escapement is of the pinwheel type but this is evidently a later modification. The original recoil escape wheel, together with its anchor, are mounted on the wall of the tower. Many of the train arbors are mounted on anti-friction rollers. There is extensive decoration. Every lever and supporting bracket is accompanied by a wealth of scroll-work; there is extensive moulding on the horizontal bars, and the end pivot bars terminate with large volutes. The whole front top bar is surmounted by elaborate ironwork decoration, of branches, leaves and flowers. There is a central cartouche containing initials above which is a crown, and elaborate leaf and flower decorations above the front corner posts. The clock itself is painted red throughout, while the decorative ironwork is picked out in green and grey, pink and gold. Around the walls of the tower is kept a whole range of spare parts. The clock is hand-wound daily, but in spite of its immense size it drives a single dial of very modest proportions.

Turret Clock #2 (Cotehele House, Cornwall) :
The Cotehele House clock is an iron-framed clock of the door-frame variety and dates from the 15th century. The clock is unusual in that it still retains its foliot, which is underslung, a not uncommon arrangement in the door-frame variety. The clock is situated in an alcove of the chapel attached to a late medieval manor house. Above the alcove is a structure resembing a chimney in which the weights are hung. The clock itself is fastened to a stout wooden post which in turn is secured to the wall. The clock owes its survival to the remoteness of the house and the innate conservatism of the noble family that lived there for generations. It must be noted, too, that conversion to pendulum control would have been difficult with the escape wheel so near the ground. The going train comprises two arbors only. The great wheel drives the escape-wheel arbor below it and is wound by capstan handles on the barrel. The foliot is suspended by means of a metal swivel and link instead of the usual cord. The striking train above the going train has a count wheel with inside notches and an elementary type of warning control. The wheel teeth are almost triangular in form, and the crown or escape wheel has long slender teeth which engage smoothly with the pallets. There is no dial, as was customary at the time. The clock has recently been overhauled with great understanding and is in going order.

Turret Clock #3 (Cuernavàca, Mexico) :
This clock, now in the Cortez Museum, Mexico City, came from the nearby cathedral. It is of birdcage type with end-to-end trains; it has a crown wheel and verge escapement and was probably converted from a foliot. There is a rectangular hole in the top crossbar to which the foliot bracket was originally fastened. Further signs of the conversion are a set in the pendulum to miss the crossbar and a notch in the top bar to allow an even greater swing. The framework terminates in outward curving feet, and the wheelwork is finely cut. These features, together with the retention of the crown wheel after conversion, suggest Dutch influence. The conversion also indicates that the clock was originally made before 1658 and was converted after that date. It is perhaps surprising that a clock in a Roman Catholic cathedral in Mexico, which was then part of the Spanish Empire, should have come from a Protestant country like Holland, but the contemporary Spanish social structure lacked an artisan class and hired skilled men from other industrious nations - the Dutch, the Swiss and the Germans. Whether the clock was made in Spain or Holland it is impossible to say. Nor is it certain whether the conversion was made in Europe or in Mexico.

Turret Clock #4 (St. Jacobstoren, The Hague) :
under construction