| 释义 |
differential, a. and n.|dɪfəˈrɛnʃəl|
[ad. med. or mod.L. differentiāl-is, f. differentia difference: see -al1. Cf. mod.F. différentiel (Dict. Trev. 1732).]
A. adj.
1. Of or relating to difference or diversity; exhibiting or depending on a difference or distinction; esp. in Comm. used of duties or charges which differ according to circumstances.
1647H. More Song of Soul i. ii. xii, This be understood Of differentiall profunditie. 1841Myers Cath. Th. iii. xxiv. 90 This testimony does not decide..the differential amount of sacredness between Substantial Divinity and Literal Infallibility. 1845McCulloch Taxation ii. v. (1852) 222 To reduce the present differential or prohibitory duties on the sugar of foreign countries. 1868Rogers Pol. Econ. xix. (1876) 5 Differential duties in favour of colonial timber. 1894Jessopp Rand. Roam. ii. 60 They compounded for murder according to a differential tariff.
2. a. Constituting a specific difference or differentia; distinguishing, distinctive, special.
1652Gaule Magastrom. 77 Any quality of sympathy or antipathy (which doe follow naturally the specifick or differentiall forms). 1733Cheyne Eng. Malady ii. xi. §1 (1734) 227 The great differential Marks of the Distemper will appear. 1851De Quincey Carlisle on Pope Wks. XIII. 24 Every case in the law courts..presents some one differential feature peculiar to itself. 1893F. Hall in Nation (N.Y.) LVII. 449/3 One of the differential peculiarities of a highly important division of the Hindus of olden times.
b. Relating to specific differences. differential diagnosis: the distinguishing between two similar species of disease, or of animals or plants.
1875B. Meadows Clin. Observ. 29 Any system of specific treatment governed by differential diagnosis. 1877Roberts Handbk. Med. I. 19 In others the diagnosis has to be more or less differential. 1883in Syd. Soc. Lex.
3. Math. Relating to infinitesimal differences (see B. 1).
differential analyser, a machine designed for solving differential equations. differential calculus: a method of calculation invented by Leibnitz in 1677, which treats of the infinitesimal differences between consecutive values of continuously varying quantities, and of their rates of change as measured by such differences. (Newton's method of fluxions was another way of treating the same subject.) differential coefficient: a function expressing the rate of change, or the relation between consecutive values, of a varying quantity: see coefficient B. 2 c. differential equation: an equation involving differentials (see B. 1).
1702Ralphson Math. Dict. s.v. Fluxions, A different way..passes..in France under the Name of Leibnitz's Differential Calculus, or Calculus of Differences. 1706H. Ditton Instit. Fluxions 17 The Fundamental Principles [of Fluxions]..appear to be more accurate, clear, and convincing than those of the Differential Calculus. 1727–51Chambers Cycl. s.v., Mr. Leibnitz..calls it differential calculus, as considering the infinitely small quantities..as the differences of the quantities; and, accordingly, expressing them by the letter d prefixed: as the differential of x by dx. 1763W. Emerson Meth. Increments 75 A differential equation. 1808Edin. Rev. Jan. 256 The general methods of integrating the differential equations above mentioned. 1816tr. Lacroix's Diff. & Int. Calculus 4 The limit of the ratio of the increments, or the differential coefficient, will be obtained. 1819G. Peacock (title), Comparative view of the fluxional and differential Calculus. 1835Macaulay Ess., Mackintosh's Hist. Rev. (1854) 321/1 We submit that a wooden spoon of our day would not be justified in calling Galileo and Napier blockheads, because they never heard of the differential calculus. 1931D. Bush in Jrnl. Franklin Inst. CCXII. 447 The differential analyzer. A new machine for solving differential equations. 1957Technology July 188/1 The analogue laboratory contains a large electro-mechanical differential analyser. 1962Gloss. Terms Automatic Data Proc. (B.S.I.) 8 Differential analyser, (1) an analogue computer using interconnected integrating gears to solve differential equations; (2) by extension, any computer designed primarily for solving differential equations.
4. Physics and Mech. Relating to, depending on, or exhibiting the difference of two (or more) motions, pressures, temperatures, or other measurable physical qualities:
a. of physical actions or effects. differential tone (in Acoustics) = difference-tone: see tone n.
1768–74Tucker Lt. Nat. (1852) I. 406 Weight is made by the differential, not the absolute pressure of ether. 1868Lockyer Elem. Astron. 318 As the Sun's distance is so great compared with the diameter of the Earth, the differential effect of the Sun's action is small. 1873B. Stewart Conserv. Energy iv. §136. 97 Wherever in the universe there is a differential motion, that is to say, a motion of one part of it towards or from another. 1877Le Conte Elem. Geol. i. (1879) 55 The centre of the glacier moved faster than the margins. This differential motion is the capital discovery in relation to the motion of glaciers. 1880E. J. Payne in Grove Dict. Mus. I. 726 Two notes..sounded together..generate a third..tone, whose vibrational number equals the difference of their several vibrational numbers..These tones Helmholtz calls differential tones.
b. of instruments or mechanical contrivances. spec. Applied to mechanisms devised for imparting differing velocities, e.g. to the two halves of the driving axle of a motor vehicle (so that the wheels revolve at different rates when turning a corner).
differential gear, differential gearing: a combination of toothed wheels communicating a motion depending on the difference of their diameters or of the number of their teeth. differential pulley: a pulley having a block with two rigidly connected wheels or sheaves of different diameters, the chain or rope unwinding from one as it winds on the other. differential screw: a screw having two threads of different pitch, one of which unwinds as the other winds. differential thermometer: a thermometer consisting of two air-bulbs connected by a bent tube partly filled with a liquid, the position of the column of liquid indicating the difference of temperature between the two bulbs. differential winding: the method of winding two insulated wires side by side in an electric coil, through which currents pass in opposite directions.
1804J. Leslie Heat 9 The instrument most essential in this research..was the differential thermometer. 1834Mech. Mag. XXI. 3 Saxton's differential pulley. Ibid. 6 The ‘locomotive differential pulley’ can never be made to answer the expectations of the inventor. 1881Maxwell Electr. & Magn. I. 433 The differential galvanometer, an instrument in which there are two coils, the currents in which are independent of each other. 1884Minchin Statics (ed. 3) I. 188 A Differential Wheel and Axle is sometimes employed. 1888Encycl. Brit. XXIII. 559 In 1877 Mr. James Starley, it is believed without any knowledge of the gear used by Fowler for traction engines, re-invented the same differential gear for tricycles. 1902A. C. Harmsworth Motors & Motor-Driving x. 213 The differential gear acts on the principle of the action of the pair-horse whippletree and equalising bar. 1903Sci. Amer. 7 Feb. 91/2 Single-chain drives are more popular than ever, although..it looked as if the double outside chain drive to both rear wheels from a differential countershaft would supplant this form. 1904A. B. F. Young Compl. Motorist iii. 62 A separate shaft, parallel with the rear axle, called the differential shaft, driven by bevel gearing from the secondary shaft in the gear case. 1925Morris Owner's Man. 26 If any adjustments to the differential bearings are required. Ibid., This adjusting sleeve is easily accessible through an opening on the upper side of the differential carrier. 1967E. Rudinger Consumer's Car Gloss. (ed. 2) 32 The differential gears are in the middle of the rear axle.
B. n.
1. Math.
a. (In the differential and integral calculus) The infinitesimal difference between consecutive values of a continuously varying quantity (corresponding to a moment or fluxion in Newton's method); either of the two quantities (usually considered to be infinitesimal) whose ratio constitutes a differential coefficient.
1704J. Harris Lex. Techn. s.v. Fluxion, This Method is much..shorter than..the French one with the Differential d multiplied into the Flowing Quantity, to denote the Fluxion. 1730–6Bailey (folio), Differential of any quantity, is the fluxion of that quantity. 1788Howard Cycl. I. 424 Multiply the differential of [each] factor into the other factor, the sum of the two [products] is the differential sought. 1819G. Peacock View Fluxional & Diff. Calc. 25 The Differential is but the measure of the rate of increase. 1880Buckingham Elem. Diff. & Int. Calc. (ed. 2) 42 The function which Leibnitz terms ‘differential’ and which Newton designates as a ‘fluxion’ is the concrete symbol which represents the rate of change in the variable.
†b. A logarithmic tangent. Obs.
1727–51Chambers Cycl., Differential, in the doctrine of logarithms. Kepler calls the logarithms of tangents, differentiales; which we usually call artificial tangents. 1845Cayley Wks. I. 145 Logarithmic differential.
2. Biol. A distinction or distinctive characteristic of structure: opp. to equivalent.
1883A. Hyatt in Proc. Amer. Assoc. Adv. Sci. XXXII. 358 During their subsequent history, characteristics are divisible into two categories: those which become morphological equivalents and are essentially similar in distinct series, and those which are essentially different in distinct series and may be classed as morphological differentials.
3. a. Comm. A differential charge: see A. 1.
1890Spectator 20 Sept. 383 The morality of American Railway Companies as regards..differentials and commissions.
b. The difference in wages between one class of workmen and another (esp. between skilled and unskilled workmen) or between one industry, etc., and another; a difference in prices of similar products, services, etc.
1941Economist 8 Feb. 178/2 The present economic differentials between one occupation and another and one status and another are, over a wide field, calculated to make people stay where they are. 1950D. W. Brogan Era of F. D. Roosevelt v. 100 Controversy arose over wage differentials between North and South. 1955Times 17 June 4/4 This trend would lift the skilled differential and the future might show a relative improvement in payment for skill. 1959Punch 19 Aug. 30/2 The rise of Oundle's fees to {pstlg}435 puts the school within {pstlg}25 of Eton... What does Eton do now? Does it preserve its status by leaping ahead.., or does it get the Headmasters' Conference to negotiate a national agreement on differentials? 1965New Statesman 23 Apr. 634/2 The major companies have reacted with countrywide cuts of 1d., 1½d. or 2d. off certain grades [of petrol]. Some..cut-price companies have followed suit, to try to keep their 3d. differential.
4. A differential gear, spec. of a motor vehicle.
1902Daily Chron. 30 June 6/2 He broke the differential of his 70 h.-p. Panhard car 50 kilometres from the finish. 1905Westm. Gaz. 17 Feb. 8/2 A motor-boat requires no differential. 1930J. B. Priestley Angel Pavement ii. 72 Wanted new plugs and mag. and brakes re-lining and something doing to the differential, and just cleanin' up a bit. 1959Motor Man. (ed. 36) iv. 94 When a rigid rear axle is used, the differential naturally moves up and down in relation to the chassis whenever the wheels meet a bump. |