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Knight's Mechanical Encyclopedia (ed. Knight) 24 0 Browse Search
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to the chains which are bolted thereto. a, cross-tunnel; b, anchor; c, suspension-cable. An′chor-drag. See drag-anchor. Anchor es-capement. The anchor escapement superseded the crown-wheel escapement for clocks. It was invented by Clement, a London watchmaker, in 1680. By some it is credited to Dr. Hooke. The anchor has two arms whose bent ends resemble flukes in some degree, and thus give rise to the name. It is suspended from a horizontal axis, on which it turns freely alor acting upon the pendulum with so great force as by the old plan; and by the introduction of a heavy ball, leaving that to be done by the uniform power of gravity which before was dependent upon the impulse given by the wheel to the pallets. Clement, in connection with this escapement, introduced his mode of suspending the pendulum by a thin piece of flexible spring, a mode which has remained in favor ever since. Anchor escapement. Figure 193 shows two forms of anchor escapement: one
uspended by strings of the same length. A. D. 1641, Richard Harris constructed a pendulum clock in London, for the church of St. Paul, Covent Garden. A. D. 1649, a pendulum clock was constructed by Vincenzio Galileo (the younger Galileo). A. D. 1650, Huyghens constructed clocks on this principle: — He first explained the nature, properties, and application of the pendulum, and made it perfect, except the compensation added by Graham, about 1700. Anchor pallets were introduced by Clement, in 1680, who also devised the mode of suspending the pendulum from a stud, by means of a piece of watchspring. The mechanism of repetition by means of pulling a string was invented by Barlow, 1676. The endless cord, to continue the clock in regular motion, during the time of winding up, was invented by Huyghens, 1660. This was otherwise effected by Harrison, 1735, by means of his auxiliary spring and additional ratchet. See going-wheel. Huyghens was also the contriver of the present di
ai Tartars of the Caspian have similar shelters. The hatters attribute the art of felting to Clement. The hatters are a very modern guild, and cannot antedate their order beyond the year 1400. 0, 1863. 41,017W. PalmerDec. 22, 1863. 44,099W. R. LandfearSept. 6, 1864. 44,127Townsend and ClementSept. 6, 1864. 44,545D. F. MellenOct. 4, 1864. 45,262W. MorgensternNov. 29, 1864. 48,133W. MorgensternJune 6, 1865. 50,334N. S. ClementOct. 10, 1865. 60,832A. A. ChassepotJan. 1, 1867. 63,217J. W. CochranMar. 26, 1867. 63,303Thomas RestellMar. 26, 1867. 65,509E. K. RootJune 4, 1867. 73nielsFeb. 15, 1838. 1,611J. R. ThomasMay 19, 1840. 13,507B. F. JoslynAug. 28, 1855. 14,949N. S. ClementMay 27, 1856. 15,307W. M. StormJuly 8, 1856. 15,516F. W. HoffmanAug. 12, 1856. 25,661J. P. Among the most remarkable fountains are the Fon- tana di Trevi at Rome, constructed for Pope Clement XII. in 1735; the Fontana Paolina, erected for Pope Paul V. in 1612; the Fontana della Acqua
sion is made for preventing, as far as possible, any change in the amplitude. The thin, flat spring by which a clock pendulum is suspended assists in maintaining the uniformity of its oscillations. The forms of the clock-escapements before Clement of London (1676) invented the anchor-escapement are not perfectly known, but were probably on the verge principle, two pallets on the axis of oscillation of the pendulum alternately escaping from the teeth of a crown-wheel propelled by the train. Clement also devised, about the same time, the mode of suspending the pendulum from a stud by a small piece of watch-spring. Graham, of London, invented the mercurial compensation pendulum (d) about 1700. In it a jar of mercury is used for the bob or weight. As the pendulum-rod is expanded longitudinally by increased temperature, the expansion of the mercury in the jar carries it to a greater hight therein, and so raises its center of gravity relatively to the rod as to compensate for
o the pendulum or balance. The vertical escapement of a watch is a recoil, and the word is used as distinguished from a dead-beat. In the former there is a recoil of the train, and in the latter the impinging surfaces of the pallets are cut to a curve concentric with the axis of vibration, and during the time one of the teeth is against the pallet the scape-wheel remains perfectly at rest. See escapement; dead-beat. Recoil clock-escapements. The anchor-escapement A was invented by Clement, of London, about 1680. The anchor is caused to vibrate on its axis by the oscillations of the pendulum. The teeth of the scape-wheel c impinge alternately against the outer surface of pallet b and the inner surface of pallet a. As these surfaces are not concentric with the axis of oscillation, a recoil of the train ensues, for the reason just stated, that as the pallets leave the teeth, the extremities of the latter slide along the acting surfaces of the pallets, and through them transmi
ventilating railway-cars. These generally embrace the following essential features: 1, a mouth adjustable toward the direction in which the train is proceeding, and having an inclined top which deflects downward the current produced by the motion of the train; 2, an arrangement to catch the dust and sparks; and, 3, a downwardly descending pipe to direct the purified air into the car. The principle is essentially that of the wind-sail employed on shipboard. Godley's car-ventilator. In Clement's patent, November 22, 1853, sponge or other porous material, kept constantly moist by water from a suitably arranged chamber, is used as an air-filter. Godley's car-ventilator acts by vacuum process. It has swiveled elbow-pipes, placed underneath the floor of the car, connecting with the interior of the latter by means of registers, and so arranged that the exit-openings are toward the rear of the train, the suction of the atmosphere having the effect of drawing the air out of the car