Horology

Collier's New Encyclopedia (1921)

that branch of science which treats of the principles and construction of machines for measuring and indicating portions of time. It is almost an impossibility to state who was the individual that intended either a clock or a watch; due to the fact that formerly the term horologium was applied to a sun dial or a clock indiscriminately. As far back as the close of the 13th or the beginning of the 14th century, striking clocks were known in Italy. In 1288, as we are told by Coke, a stone clock tower was erected opposite Westminster Hall, and in it was placed a clock. About 1364 a German horologer, Henry de Wick, de Vick, de Wyk, or de Wyck, set up a clock in the tower of the palace of Charles V. of France. The date at which the size of clocks was so far reduced as to render them portable, is uncertain; it must, however, latter year the corporation of master clockmakers at Paris procured from Francis I. a statute precluding all but master clockmakers from constructing clocks or watches, large or small. The third era in clockwork was the application of the pendulum. Galileo was the first who remarked, or at least the first who formally announced, in his work on mechanics and motions by which the original rotatory motion is which was published in 1639, the iso- converted into a reciprocating motion, chronal property of oscillating bodies suspended by strings of the same length. In a general view, horological machines may be regarded as consisting of three essential parts: 1. A moving power, which produces a rotary motion about an axle; 2. A train of wheelwork, by means of which a velocity is obtained having any required ratio to that of the primary axle; 3. A regulator, by which the rapidity of the revolution is determined, and uniformity of motion produced. The moving power is either a heavy weight, which descends by the force of gravity, or a spring which is coiled up within a barrel and unwinds itself by the force ATLAS AXIS SKULLA DORSAL VERTEBRA SCAPULA HUMERUS. STERNUM ULNA RADIUS COPISIFORM BONE CARPUS LARGE METACARPAL SMALL METACARPAL -SESAMOID BONE LARGE PASTERN, SMALL PASTERN COFFIN BONE of its elasticity; the first is preferred on account of the perfect regularity of its action when the instrument is to remain fixed in a place; the second is necessary for pocket timepieces and those which cannot be kept in a fixed position, as on shipboard. The train of wheelwork is chiefly remarkable on account of the delicacy and accuracy of its construction. The regulator is either a pendulum, of which, by the theory of falling bodies, the oscillations are isochronal or performed in equal terms; or a heavy balance, the reciprocal vibrations of which are also isochronal. Of the various mechanical contrivances introduced into horological machines for accomplishing particular purposes, the most important is the escapement (or scapement), or that part of the mechanism and gives impetus to the pendulum or balance. Some other parts are also of primary importance, as the maintaining power, a contrivance by means of which the motion is maintained or the machine kept going while the weight or spring is being wound up; the fusee by which in watches and spring clocks the force acting on the wheel work is rendered equal in all states of the tension of the spring. Electrical clocks are of two kindselectrical dials and electrical clocks. The electrical dial has no body belonging to it, but is connected by means of a wire with a standard clock at some SACRUM LUMBAR VERTEBRA TUBEROSITY OF MSCHIUM -RIBS PELVIS THIRD FEMUR TROCHANTER PATELLA FIBULA TIBIA CALCENEUM HOCK LARGE SPLINT METACARPAL FETLOCK PASTERN HOOF SKELETON OF HORSE other place. An apparatus is also provided for sending a galvanic current through the wire at certain regular intervals of time. By this means the dial hands are made to leap over a small portion of their compass whenever a current is transmitted through the wire; and the time value of the movement is marked by the figures on the dial. An electric clock, however, is one that carries with it its sources of power and is independent of any wire connected with another place.