Time Telling through the Ages

Abrasion – Wearing away by rubbing or friction.

Adams, J. C. – A promoter instrumental in organizing the Elgin, Illinois, Cornell, and Peoria Watch Companies, and the Adams & Perry Manufacturing Company. He invented and patented the "Adams System" of time records in use on most of the railroads in the West. He last appeared in prominent connection with the watch and clock business as the organizer of the Swiss horological exhibit at the World's Columbian Exposition.

Addenda – Tips of the teeth of a wheel beyond the pitch circle. Sometimes of circular outline; sometimes ogive – that is, of a shape patterned after the pointed arch. The addendum is also known as the "face" of the tooth.

Adjustment – The manipulation of the balance with its spring and staff to secure the most accurate time-keeping possible. Three adjustments are usually made, viz.: for isochronism, temperature and position. Much of the difference in value and cost of watches depends on this operation.

Adjustment to Isochronism – Strictly speaking this would cover all adjustment; but it is technically understood to mean an adjustment of the balance spring so that the time of vibration through the long and short arcs of the balance is the same.

Adjustment to Positions – The manipulation of the balance and its spring so that a watch keeps time in different positions. Good watches are usually adjusted to five positions. They are pendant up; III up; IX up; dial up; and dial down.

Adjustment to Temperature or Compensation – The adjustment of the balance and spring so that the time-keeping qualities are affected as little as possible by changes in temperature. See Compensation (#Compensation).

Ahaz – King of Judea, 742-727 B. C. See Dial of Ahaz (#Dial_of_Ahaz).

Alarm – Sometimes spelled "alarum." A mechanism attached to a clock whereby at any desired time a bell is struck rapidly by a hammer.

Aluminum-Bronze – An alloy of aluminum and pure copper, usually in the proportion of 10 parts of the former and 90 of the latter. It is considerably lighter than brass and highly resistant to wear.

Anaximander – Greek astronomer to whom the Greeks ascribed the invention of the sun-dial in the sixth century B. C.

Arbor – The axle or axis on which a wheel of a watch or clock turns. Also applied to a spindle used by watchmakers.

Arc – Any section of the circumference of a circle.

Archimedes – A famous Greek philosopher and scientist sometimes credited with the invention of the clock. About 200 B. C. he made a machine with wheel work and a maintaining power but having no regulator it was no better as a time teller than a planetarium turned by a handle. It may have furnished the suggestion for later time-keeping machines.

Arnold, John – Born 1736. An English watchmaker of note. He invented the helical form of the balance spring and a form of chronometer escapement much like Earnshaw's. Died 1799. Arnold's devices have been most useful and permanent.

Assembling – The putting together of the finished parts of a watch. In a three-quarter plate watch this is done on the lower plate. In a full plate movement it is easier and more satisfactory to assemble on the top plate.

Astrolabe – 1. An instrument of various forms formerly used especially in navigation to measure the altitudes of planets and stars. 2. A projection of a sphere upon any of its great circles.

Astronomical Time – Means solar time, as computed from observing the passage of the sun across the meridian from noon of one day to noon of the following day. It is counted continuously up to 24 – not in two 12-hour divisions.

Astronomy – The science which treats of the motions, real and apparent, of the heavenly bodies. Upon this science, through its determination of the length of the year, is founded the science of horology – or time-keeping.

Automata – for Striking – Very common on old clocks and very complicated, such as: Indian King hunting with elephants, Adam and Eve, Christ's flagellation, and many others. See Clocks, Interesting Old (#Clocks_Interesting_Old).

Automatic Machinery – The second great contribution of America to watchmaking after the establishment of the principle of interchangeability of parts, and making possible the effective execution of that principle.

Auxiliary – A device attached to a compensation balance to reduce what is known as the "middle temperature error." Some are constructed to act in high temperatures only – as Molyneux's; and some in low temperatures only – as Poole's.

Balance – The vibrating wheel in a watch or chronometer which with the aid of the balance spring (hair-spring) regulates the rate of travel of the hands. The balance is kept in vibration by means of the escape wheel. See Compensation Balance (#Compensation_Balance).

Balance Arc – In detached escapements, that part of the vibration of the balance in which it is connected with the train. The remainder is called the drop.

Balance-Clock – A form of clock built before the pendulum came into use. The regulating medium was a balance on the top of the clock made with a verge escapement. See Foliot (#Foliot).

BALANCE COCK

Balance Cock – The standard which supports the top pivot of the balance. In old watches often elaborately pierced and engraved.

Balance Spring – In America usually called the "hair-spring." A long slender spring that governs the time of vibration of the balance. One end of the balance spring is fastened to a collet fitted friction-tight on the balance staff, the other to a stud attached to the balance cock or to the watch plate. The most ordinary form is the volute, or flat spiral. The other form used is an overcoil. See Bréquet Spring. The principle of the isochronism of a balance spring was discovered by Hooke, and first applied to a watch by Tompion. The name hair-spring comes from the fact that the first ones are said to have been made from hog bristles.

Balance Spring Buckle or "Guard" – A small stud with a projecting tongue attached to the index arm and bridging the curb pins so as to prevent their engaging two of the balance spring coils. Used chiefly in Swiss watches.

Balance Staff – The axis of the balance. The part of a watch most likely to be injured by a fall.

Balance Wheel – A term often incorrectly applied to the balance itself, but properly it is the escape wheel of the verge escapement.

Band – Of a Watchcase – The "middle" of the case to which the dome, bottom and bezel are fastened; the last sometimes screwed, sometimes snapped.

Bank – Banking-pin.

Banking – In a lever watch the striking of the outside of the lever by the impulse pin due to excessive vibration of the balance. In a cylinder or verge movement the striking of the pin in the balance against the fixed banking-pin.

Banking-Pin – A pin for restricting the motion of the balance in verge and cylinder watches.

Banking-Pins – 1. In a lever watch, two pins which limit the motion of the lever. 2. In a pocket chronometer, two upright pins in the balance arm which limit the motion of the balance spring. 3. In any watch, the curb pins which confine the balance spring are sometimes called banking-pins.

Barlow, Edward (Booth) – A clergyman of the Church of England, born in 1636. He devoted a great deal of time to horological pursuits. He invented the rack repeating striking works for clocks, applied by Tompion in 1676. He invented also a repeating works for watches on the same plan. And he invented the cylinder escapement which he patented with Tompion and Houghton. When he applied for a patent on his repeating watch he was successfully contested by Quare, who was backed by the Clockmakers' Company. He died in 1716.

Bar Movement – A watch movement in which bars take the place of the top plate and carry the upper pivots. Sometimes termed a "skeleton" movement. Not generally adopted because its many separate bearing parts promote inaccuracies where large quantities are to be produced.

Barrel – A circular box which confines the mainspring of a watch or clock.

Barrel Arbor – The axis of the barrel around which the mainspring is coiled.

Barrel Hollow – A sink cut either into the top plate or the pillar plate of a watch to allow the barrel freedom.

Barrel Hook – A bent pin in the barrel to which the mainspring is attached.

Barrel Ratchet – A wheel on the barrel arbor which is prevented by a dog from turning backward while the mainspring is being wound and which becomes the base against whose resistance the train is driven.

Bartlett, P. S. – One of the early watchmakers of America. Connected with the Waltham factory at first and later with the Elgin Company. It is said that he first proposed the formation of the company at Elgin. His name became familiar as a household word throughout the country from being inscribed upon a full-plate model which attained widespread success.

Beat – The strike or blow of the escape wheel upon the pallet or locking device.

Beat Pins – The pins at the ends of the pallets in a gravity escapement which give impulse to the pendulum.

Beckett, Sir Edmund – See Denison (#Denison), Edmund Beckett.

Berosus – A Chaldean historian who lived at the time of Alexander the Great, about 200 B. C., and was a priest of Belus at Babylon. Said to have been the inventor of the hollow sun-dial. He was the great astronomer of his age.

Berthoud, Ferdinand, 1727-1807 – An eminent French watchmaker and writer on horological subjects. Among his books are: "Essai sur l'Horlogerie," "Traite des Horloges Marines," and "Histoire de la mesure du Temps." He was a Swiss by birth, but lived most of his life in Paris.

Bezel – The ring of a watch or clock case which carries the glass or crystal in an internal groove.