| 释义 |
▪ I. pendulum, n.|ˈpɛndjʊləm|
Pl. -ums, formerly (rarely) -a.
[a. mod.L. pendulum (1643 in Watt Biblioth.), n. use of neut. of L. pendul-us pendulous, lit. a pendulous or free-hanging body; in It. pendolo (Galileo Operazioni Astronomiche, 1637).]
1. a. A body suspended so as to be free to swing or oscillate; usually, an instrument consisting of a rod, with a weight or bob at the end, so suspended as to swing to and fro by the action of gravity, and used for various mechanical and scientific purposes; esp. as an essential part of a clock, serving (by the isochronism of its vibrations) to regulate and control the movement of the works, so as to maintain a constant rate of going, and enable it to keep regular time.
1660Boyle New Exp. Phys. Mech. xxvi. 202 We thought it not amiss to try if a Pendulum would swing faster, or continue swinging longer in our Receiver. Ibid. xxxvii. 316 We conveyd into our Receiver..the Pendula formerly mention'd. a1677Hale Prim. Orig. Man. ii. iv. 152 The late discovery of the Motion of the Pendulum. 1685Boyle Effects of Mot. vi. 69 The great swing that may be given to Pendulums by a very languid force, if it successively strike the swinging body. 1785S. Fielding Ophelia II. i, She was as regular as a pendulum. 1844Herschel Ess. (1857) 583 Two pendula, a copper and an iron one,..were furnished by the Society. 1879A. M. Clerke in Encycl. Brit. X. 31/1 The experimental verification of this fact led him [Galileo] to the important discovery of the isochronism of the pendulum.
b. With qualifying word. compound pendulum, (a) a pendulum consisting of a number of weights at fixed distances; an actual material pendulum regarded theoretically, as opposed to a simple pendulum (see below); (b) a compensation pendulum whose rod consists of bars of different metals. conical pendulum, a pendulum so contrived that the bob revolves in a circle, the rod thus describing a cone. mercurial (or † quicksilver) pendulum, a compensation pendulum with a cylindrical bob containing mercury, whose upward expansion by heat counteracts the lengthening of the rod. seconds pendulum, a pendulum of such a length as to oscillate once every second; a pendulum ‘beating seconds’. simple pendulum, (a) a theoretical or ideal pendulum consisting of a particle having weight but no magnitude, suspended by a weightless inextensible rod, and moving without friction; (b) a pendulum consisting simply of a bob suspended by a cord or wire, without any special contrivance, as for compensation of the effects of heat; (c) a pendulum unconnected with any mechanism. spherical pendulum, a pendulum so contrived that the bob can move in any circle on a given spherical surface (the same as conical pendulum). See also ballistic p., compensation p., cycloidal p., gridiron p., hydrometric p.
1726Graham in Phil. Trans. XXXIV. 42 The Irregularity of the Clock, with the Quicksilver Pendulum..exceeded not..a sixth Part of that..with the common Pendulum. 1727–41Chambers Cycl. s.v., Simple Pendulum..Compound Pendulum. 1795Hutton Math. Dict. II. 207 The length of a Pendulum, so measured..that it will perform each vibration in a second of time, thence called the second's Pendulum. Ibid. 210 Simple Pendulum, and Detached Pendulum, are terms sometimes used to denote such Pendulums as are not connected with any clock, or clock-work. Ibid., The Mercurial Pendulum was the invention of the ingenious Mr. Graham..in 1715. 1819Pantologia s.v., The conical or circular pendulum, is so called from the figure described by the string or ball of the pendulum. 1862Cayley Coll. Math. Papers IV. 525 That the motion of the spherical pendulum is sensibly affected by the rotation of the Earth is the well-known discovery of Foucault. 1871Tait & Steele Dynamics of Particle (ed. 3) §208 The Conical Pendulum, as it is called, when the particle moves in a horizontal plane and therefore in a circular path, the string describing a right circular cone whose axis is vertical.
c. Used of similar bodies that oscillate but are not similarly suspended: horizontal pendulum, an approximately horizontal rod having a heavy weight at one end and pivoted at the other so that it can swing freely in an approximately horizontal plane, supported by a thread or wire passing from the weighted end to a fixed point almost vertically above the pivot; inverted pendulum, a vertical rod having a heavy weight at its upper end and resting on a bearing at the other, and held in position by springs which allow it to oscillate in a vertical plane.
1844Trans. R. Soc. Edin. XV. 219 The elegant inverted Pendulum or Noddy contrived by the late Mr Hardy. 1872F. Zöllner in Phil. Mag. XLIII. 491, I explained the principles of such a method and its practicability in an apparatus for which I proposed the name of ‘Horizontal Pendulum’, in order to distinguish it from other pendulum-like instruments, also suspended by two threads. 1908C. G. Knott Physics Earthquake Phenomena iv. 61 The nearer the point of attachment to a truly vertical position above the pivot the more delicate and the less stable will the horizontal pendulum be, and the better fitted for recording small motions. 1937D. Kennedy tr. Imamura's Theoret. & Appl. Seismol. xi. 254 The form most extensively used is one that weighs a ton. It is shown in Fig. 119. The heavy bob is an inverted pendulum. Its lower point, the end of the supporting rod, rests in a socket, but as it is unstable in this condition, an arm..extends laterally from the upper end of the pendulum, and connects with a steel spring. 1972R. B. Gordon Physics of Earth vi. 124 An instrument suitable for recording horizontal ground motion is the horizontal pendulum.
d. Mountaineering. A swinging movement like that of a pendulum, often used as a deliberate move by a climber using his momentum to swing to a new position. Also attrib.
1945G. W. Young Mountain Craft (ed. 4) v. 179 The second [artificial aid] is the pendulum. Like most modern technical devices, it is a perfecting of an old alpine fashion... By attaching a rope to the highest point convenient upon our first line, we..can swing across upon it, and reach the new set of holds. 1949A. Roch Climbs of my Youth xiv. 115 The pendulum was definitely unpleasant, and a few stones fell loose. 1965A. Blackshaw Mountaineering ix. 268 If there is no suitable transverse crack it will be necessary to do a pendulum or a horizontal rappel. The former involves abseiling..from a piton and swinging over to the desired new position. 1971C. Bonington Annapurna South Face x. 120 He therefore had to climb without any protection from pitons, though if he had fallen off he would have had a punishing pendulum back into the gully. 1972D. Haston In High Places x. 110 There are some devious pendulums to reach the start of the main crack system. A pendulum is an exciting move, very common to Yosemite climbing. When one line of cracks runs out and there is blank wall before another can be reached, often this gap can be filled in by fixing a piton as high as possible, going down for some way hanging on the rope, then running back and forth to get up enough momentum to make a swing into the next crack system.
2. a. fig. In reference to oscillation (of a person, or of opinion, etc.) between two opposites.
1769Junius Lett. xv. (1771) 72 Is this the wisdom of a great minister? or is it the vibration of a pendulum? 1818Byron Ch. Har. iv. cix, Man! Thou pendulum betwixt a smile and tear. 1836Penny Cycl. V. 300/1 The pendulum of opinion swings to the side opposite to that on which it has been unduly brought out of its position of equilibrium. 1900Westm. Gaz. 8 Nov. 4/2 The moral of the Canada elections is that there is no swing left in the Pendulum anywhere.
b. to play pendulum: to swing or oscillate like a pendulum (lit. or fig.).
1893Saltus Madam Sapphira 171 Beyond asking him to play pendulum I see nothing. 1897M. Kingsley W. Africa iv. 77 Great rollers..make the vessels lying broad⁓side on to them play pendulum to an extent that precludes the discharging or taking on of heavy cargo.
†3. A clock that goes by means of a pendulum, a pendulum-clock; also, a pendulum-watch (4 b).
1664–5Phil. Trans. I. 14 The same Objection..against the exactness of these Pendulums, hath also been made here... This difference..will not be at all perceived in the Penduls. 1696Derham Artif. Clockm. 62 For the use of such as would convert old Ballance Clocks into Pendulums. 1706Phillips, Royal Pendulums, are those Clocks whose Pendulum swings Seconds, and goes eight Days, shewing the Hour, Minutes and Seconds.
4. attrib. and Comb.
a. simple attrib., Characterized by oscillation, or by regular movement from side to side.
1820Sporting Mag. VII. 108 The pendulum shake [of the hand] may be mentioned next. 1865Englishm. Mag. Jan. 13 The popular mind in England has..swayed from side to side in a somewhat pendulum-fashion.
b. Comb., as pendulum-rod; pendulum-like adj., pendulum-wise adv.; † pendulum-balance, the balance-wheel of a watch, acting as a pendulum; pendulum-ball, -bob, the heavy ball or bob forming the lower end of a pendulum; pendulum-clock, a clock that goes by means of a pendulum; pendulum-cock [cock n.1 16] (see quot.); pendulum governor [governor 8], a governor consisting of two equal pendulums attached to and revolving with a spindle driven by the engine or machine to be controlled, and operating by ‘centrifugal force’; pendulum-hausse, a hausse or breech-sight for a gun, so contrived as to remain vertical when the wheels of the gun-carriage are not on a level; pendulum-level, a plumb-level: see quot.; † pendulum-piece, a time-piece having a pendulum, a pendulum-clock; pendulum position Billiards, a position of the two object balls beside the cushions on either side of a corner pocket which makes a large number of cannons possible; pendulum-press, a punching-press in which the punch is driven by a swinging treadle; pendulum-pump, (a) ‘a pump in which a pendulum is employed to govern the reciprocating motion of the piston’; (b) ‘a direct-acting donkey-pump in which the fly-wheels have an oscillatory motion in a vertical plane’; (c) ‘a pump the handle of which swings each side of its center of suspension’ (Knight Dict. Mech.); pendulum saw (see quot. 1958); pendulum-spindle, a spindle having a pendulum attached, which it causes to revolve; pendulum-spring, † (a) the coiled hair-spring connected with the balance-wheel (pendulum-balance) of a watch (obs.); (b) the spring to which the pendulum of a clock is attached; pendulum swing, a swing or swinging movement like that of a pendulum; also fig.; † pendulum-watch, a watch of the modern type, with a balance-wheel provided with a spring and oscillating regularly, thus having the function of the pendulum of a clock (obs.); † pendulum wheat (see quot.); pendulum-wheel, (a) the escapement-wheel of a clock; (b) the balance-wheel of a watch (?obs.); pendulum-wire, flat steel wire used for the pendulum-springs of clocks.
1878Abney Photogr. (1881) 255 The *pendulum apparatus, which in general outline consists of a pendulum swinging in front of sensitised paper in such a manner as to give a gradation of exposure to it, and a consequent variation in tint.
1680Lond. Gaz. No. 1538/4 Lost.., a Silver Watch..with the Hours and Minutes, a *Pendulum Ballance, without String or Chain.
a1688Villiers (Dk. Buckhm.) Militant Couple Wks. (1775) 128 Sir John pushes my lady against a fine new *pendulum-clock. 1898P. Manson Trop. Diseases xiv. 226 The sounds of the heart are, like the beats of a well-hung pendulum-clock, evenly spaced.
1884F. J. Britten Watch & Clockm. 62 In clocks, the *pendulum cock is the bracket supporting the pendulum. a1859,1887*Pendulum hausse [see hausse].
1727–41Chambers Cycl., Plumb, or *Pendulum Level, that which shews the horizontal line, by means of another line perpendicular to that described by its plummet, or pendulum.
a1721J. Keill Maupertuis' Diss. (1734) 2 In the year 1672, Mr. Richer going to Cayenne..observed that the *Pendulum-piece he had carried with him, retarded considerably in respect of the Sun's mean Motion.
1927Daily Express 26 Apr. 9/4 Reece..made a record break of 1,151, including 568 cannons by what is known as the ‘*pendulum position’.
1752Ellicott in Phil. Trans. XLVII. 480 Holes drilled in the broad part of the *pendulum-rod. 1822J. Imison Sc. & Art I. 82 A pendulum-rod is longer in warm than in cold weather.
1957*Pendulum saw [see goose saw s.v. goose n. 8]. 1958N.Z. Timber Jrnl. Jan. 46/1 Pendulum saw, a machine cross-cut saw that is drawn across the stationary wood in the process of cutting by swinging from the point of suspension like a pendulum.
1727Phil. Trans. XXXV. 304 A very irregular Motion..like the *Pendulum-Spring of a Watch. 1884F. J. Britten Watch & Clockm. 192 In small clocks the pendulum spring is often too stout.
1926Amer. Speech I. 632/2 *Pendulum swing, applied to a type of putting stroke. 1947C. Day Lewis Colloq. Element Eng. Poetry 9 The verse of the Romance poets, of the early Elizabethan lyricists,..and of the Pre-Raphaelite poets represents a series of pendulum-swings towards the formal, esoteric ideal of poetic diction. 1968J. Winearls Mod. Dance (ed. 2) ii. 57 The principle of the outside fall and pick up of a Pendulum Swing can be used in isolated leg and trunk movements.
1664Phil. Trans. I. 13 Concerning the success of the *Pendulum-Watches at Sea for the Longitudes. 1678Phillips (ed. 4), Pendulum Watch,..newly invented by Monsieur Christian Hugens of Zulichem,..in which by a Pendulum or Regulator, the time is more exactly proportioned than ever hitherto.
1707Mortimer Husb. (1721) I. 127 In Berkshire is a Wheat called *Pendulum Wheat, from its hanging of its Ear much like the Cone-wheat [cf. quot. 1677 in pendule 4].
1825J. Nicholson Operat. Mechanic 492 Affected by any unequal impulse of the *pendulum-wheel upon the pallets.
1892Pall Mall G. 12 Feb. 4/2 One of the electric lights that swung *pendulum-wise from the ceiling arrested the attention of the House.
▪ II. ˈpendulum, v.
[f. the n.]
intr. To hang or swing like a pendulum. Also fig.
1885W. F. Crafts Sabbath for Man vi. 458 The Sabbath of our fathers..was far better than the extreme of laxity to which we have pendulumed. 1949A. Roch Climbs of my Youth xiv. 115 We had to drive a piton into a slab and then pendulum across over the ice of the couloir. 1969J. Elliot Duel i. iv. 79 A stop-watch on a long black string pendulummed from her neck. 1971C. Bonington Annapurna South Face xii. 145 My progress had dropped to a single push of my jumar clamps at a time; my feet slipped on the snow steps, and I pendulumed clumsily across the arête into the gully. 1973― Next Horizon x. 146 But what if..you miss the other side and go penduluming back against the sheer ice wall, to be left hanging in the void? 1974H. MacInnes Climb to Lost World xii. 212 ‘I'll belay you from here,’ said Don. ‘Then, if the stone comes away, at least you'll pendulum over to this side and shouldn't hurt yourself too much.’ |