Time & Clocks Dictionary
Lacquered Case: Wooden clock case finish for which the painter employed powder and lacquer to produce raised, coloured patterns. Popular from about 1700 to 1730 for LONG CASE CLOCKS, and still enjoying some vogue for small clocks today. Also called 'japanned case'.
Lacquering: Exposed brass parts of clocks and MARINE CHRONOMETERS are usually given a coat of clear lacquer to avoid discoloration and corrosion. A LACQUERED CASE has a different process applied to it.
Lamp Clock: Early timekeeper comprising a lamp with a glass reservoir scaled to indicate time as the oil burned away. See Candle Clock.
Lancet Clock: Wooden-cased clock, shaped like a Gothic arch, made during the first part of the nineteenth century after the period of hand-made clocks.
Lantern Clock: Form of clock with lantern-shaped brass case made in England for about a century after 1630 or so. Most had one hand; all were weight-driven with a bell on top and stood on a wall bracket. The first had BALANCES without springs and later ones had PENDULUMS.
Lantern Pinion: Earliest form of gear, like a squirrel cage, or cylinder, made up of rods fitting into disc ends. Still used in some American alarm clocks. See Pinion.
Leaf: Clockmaker's name for a tooth of the small driven gear wheel called a 'PINION'.
Left-Handed Watch: Swiss wrist-watch with winding button on opposite 9 instead of 3 and regulated for wearing on the outside of the right wrist.
Lepine Calibre: In the eighteenth century, all watches had their BALANCES outside the two circular PLATES that comprised the watch FRAME. About 1770, Antoine Lepine began making watches with one plate and a number of COCKS Or BRIDGES, the balance being within the frame. This made the construction much thinner and heralded the modern watch. French makers adopted this style, but English continued with the old ideas for about a century.
Le Roy, Julien (1686-1759): Most famous French maker, particularly of REPEATER watches. Horologer du Roi. Perfected the OIL SINK about 1725 and may have invented the rod GONG arid DUMB REPEATER. Often used the CYLINDER ESCAPEMENT designed by GRAHAM. His son Pierre (1717-85), also Horologer du Roi, became as famous, particularly for MARINE CHRONOMETERS, his finest (now in the Musee des Arts et Metiers, Paris) having one of the first DETACHED ESCAPEMENTS, a temperature COMPENSATED BALANCE arid ISOCHRONOUS hairspring. This had more future influence on marine chronometers. See Sully.
Lever Escapement: The most successful of all ESCAPEMENTS, invented by Thos. Mudge in 1759 for QUEEN CHARLOTTE'S WATCH, and improved by Josiah Emery, in 1785, who added DRAW. Now used in almost all watches and PLATFORM ESCAPEMENT clocks, in conjunction with a BALANCE WHEEL arid HAIRSPRING. Also called 'detached lever' because of the freedom of the balance. Capable of high timekeeping performance. From Fig. 17, the balance swings clockwise and the RUBY PIN on it enters the lever fork, moving the lever upwards. This releases the ESCAPE WHEEL tooth marked A, which moves across the exit PALLET stone, pushing it right. This IMPULSES the balance in the same direction as it is swinging by causing the lever fork to thrust on the ruby pin. The escape wheel is stopped from turning further (under the influence of the MAINSPRING) by tooth B coming against the side of the entrance pallet. On the return swing of the balance (under the influence of the HAIRSPRING), the lever is knocked the other way and the balance impulsed anti-clockwise by tooth B acting on the entrance pallet. Called 'anchor' on the Continent owing to its similarity to the ANCHOR ESCAPEMENT.
Lever Watch: Loose term meaning a watch which has a LEVER ESCAPEMENT with jewelled PALLETS, although a PIN PALLET watch is also a lever.
Light Clock: Modern Swiss clock by Patek Philippe which is wound by the action of light on a photo-electric cell, the small current produced turning a motor which winds the MAINSPRING. The mainspring gives a reserve of power for the darkness and the clock therefore never needs to be wound.
Lightfoot, Peter: Traditional maker of fourteenth century elaborate clock at Glastonbury Abbey and WELLS CATHEDRAL CLOCK. Both Wells and SALISBURY clocks were more likely made by a Johannes Lietuyt of Delft, Holland, for Bishop Erghum. But Lightfoot may have been a contraction of 'Lietuyt'. See British Horological Industry.
Lighthouse Clock: Tall table clock shaped like a lighthouse with a clock dial in the tower. Where the lamphouse would be is a cylinder made up of glass prisms, which rotates. In one version the 'lamphouse' is actually a TORSION PENDULUM controlling the clock. Made in France in the nineteenth century. Another form has a rotating clock dial in the top under a glass dome.
Ligne: Watchmaker's measure equal to about 1/11TH inch, or 2.26 mm. Originated in France as 1/12th pouce, or French inch. Commonly used today, as in a '10 ligne MOVEMENT', but slowly being replaced by millimetres. In the past, lignes differed in various countries; there was an English line, and 12 of them or 3 barleycorns made an inch. See Size.
Limoges Enamel: Painted opaque enamel decoration for watch cases from 1500-1600. See Enamelled Watch.
Local Time: Time in a particular place or area. This was SOLAR TIME when timekeeping was by SUNDIAL. It became mean solar time after clocks came into general use. Now it normally means STANDARD TIME.
Locking: The action of an ESCAPEMENT when it 'locks' or holds up a tooth of the ESCAPE WHEEL.
Locking Plate: Early form of COUNT WHEEL, or in modern parlance 'memory', for STRIKING clocks. Notches in the rim decide how many hammer blows the striking TRAIN will give after being released at the hour. Really a misnomer. Gradually superseded by RACK STRIKING after 1676. Most locking plates are outside the BACK PLATE of a clock, but some early ones were between the plates. Locking plate striking can become out of step with the time shown, but is easily set right by releasing the striking train without touching the hands until the two agree.
London Museum Collection: European sixteenth to eighteenth century clocks with some fine early German examples, at Kensington Palace, London.
Long Case Clock: Clock in a wooden case usually over 6 ft. tall standing on the floor. The MOVEMENT usually runs for 30 hours or for eight days, has a long PENDULUM ticking seconds, strikes the hours and sometimes the quarters also, and often has a CALENDAR DIAL, sometimes a MOON DIAL, and even a TIDAL DIAL. The first were introduced in England before 1660, probably originating from casings put around the weights of HANGING CLOCKS. They were also made in Holland, where the pendulum clock was invented. In the seventeenth and eighteenth centuries, they were made in large numbers; even the makers numbering tens of thousands. Most best makers went to London to work, but Edinburgh was another centre. CASES were often of oak with an ebony, walnut, or mahogany veneer. London set the style; country makers were slow to follow. DIALS of the best clocks were of brass, silvered on the CHAPTER RING bearing the engraved numbers. After about 1790, painted iron dials appeared, cases became uglier, and movements were quantity produced. In the nineteenth century mass-produced MANTEL CLOCKS superseded them. Another seventeenth-century name was 'coffin clock'; the name GRANDFATHER CLOCK did not become popular until much later.
Long Pendulum: A PENDULUM that swings from one side to the other in one or more seconds and is therefore a metre or more in length (see Seconds Pendulum and Two-Seconds Pendulum). T110 RYE CHURCH CLOCK has a BEAT of 2j sec. approx. So do the St Peter and St Paul Deddington, Oxon., and the Ringwood, Hants, church clocks. St Peter's Church at St Albans; Retford, Notts; and Antrim Parish Church, Northern Ireland, clocks have 21 sec. approx. pendulums. There are 3-sec. pendulums (about 29 ft. 4 in. long) on the clocks of Churchill Church, Oxon., and Lewknor Church, Oxon., and a 4-sec. pendulum (approx. 52 ft. 2 in. long) on St Chad's Church clock, Shrewsbury.
Longitude: The angular distance east or west from longitude zero through GREENWICH OBSERVATORY, on which LOCAL and STANDARD TIMES, arid NAVIGATION depend.
Lug: Shaped part of a watch CASE to which the strap or bracelet is attached.
Luminous Dial: The most successful means of making watches and clocks (particularly alarms) suitable for night use is to luminize the hands and dials. First applied in the U.S.A. at the beginning of the twentieth century, when the dangers were not understood and those who licked their paint brushes eventually died from radiation illness. There is no danger of radiation to the user, from properly luminized dials. The four million odd luminous watches and ten million luminous alarms in Britain give only one-hundredth of the natural background radiation from the Earth and outer space that no one can avoid. Luminous paint is a mixture of phosphor and a tiny amount of radium. The phosphor transforms the invisible radio-active rays from the radium into visible light. On good watches there are only thin fillings of luminous paint in the hands and small dots on the dial. Some have the paint under the hands. The colour of the glow is often made green because the eye is most sensitive to this colour. Some modern British SYNCHRONOUS alarms have electro-luminescent dials, the tension of electricity producing a glow without radiation.
Lund Cathedral Clock: Fine large astronomical clock with AUTOMATA in Lund, Sweden, the original going back to 1380.
Lyre Clock: Elegant mantel clock inspired by the stringed instrument and invented by Kinable, of Paris (d. 1825). A fine one by him is in the VICTORIA AND ALBERT MUSEUM COLLECTION. The curved frame of the 'lyre' is of marble or bronze with the clock dial near the bottom. A GRIDIRON PENDULUM above the clock (suggesting the strings) is connected through its BOB to the clock ESCAPEMENT. Copied in large numbers in the U.S.A. after the Civil War.