| 释义 |
instantaneous, a.|ɪnstənˈteɪniːəs|
[f. L. type *instāntāne-us, after mōmentāneus (prob. in med. or mod.L.: cf. F. instantané, 1734 in Hatz.-Darm.), f. instānt-em instant; see -eous. Cf. momentaneous, simultaneous.]
1. a. Occurring or operating in an instant; done, completed, or reaching completion without any perceptible lapse of time.
1651Baxter Inf. Bapt. 194 Justification is a continued Act, and not any Instantaneous act. 1657Reeve God's Plea 29 God's knowledge is instantaneous. 1737Thomson To Mem. Ld. Talbot 27 His Reason saw, With instantaneous View, the Truth of Things. 1822J. Imison Sc. & Art I. 462 The motion of electricity..is so rapid, that it appears to be instantaneous. 1878Lecky Eng. in 18th C. I. i. 30 The effect on the English nation was instantaneous.
b. Photogr. Applied to an exposure whose duration is brief and predetermined by means of a shutter mechanism; orig. applied to those sufficiently brief for a moving object to be photographed (in contrast to the time exposures that were usual), and later to those for which the camera may be held in the hand (see quots.). Also transf., applied to a shutter designed for taking such exposures, a photograph taken with one, etc. Now chiefly Hist.
1851Athenæum 6 Dec. 1286/2 (heading) On the production of instantaneous photographic images. 1858Sutton & Worden Dict. Photogr. 229 Photographs obtained in a fractional part of a second of time are said to be instantaneous. 1867Sutton & Dawson Dict. Photogr. 156 Mr. England and others use a guillotine sort of shutter, with a slot across it, which falls immediately in front of the sensitive plate... In some respects this is the best instantaneous shutter that has yet been devised. 1884Gaiety Theatre Programme Oct. in L. de Vries Victorian Advts. (1968) 99/3 Superior Sets, comprising..Rectilinear Lens, with Instantaneous Shutter, suitable for taking instantaneous pictures of yachts sailing. 1891W. E. Woodbury Encycl. Photogr. 356 Instantaneous dry plates are those coated with a very highly-sensitive emulsion that will become sufficiently impressed by the rapid exposure of the image upon it. An instantaneous lens is one that admits a large amount of actinic light. Ibid. 357 Instantaneous Photography.—In the very earliest days of photography this term was applied to what would now be considered very slow work indeed. We now usually apply this term when the exposure does not exceed one second. 1902Encycl. Brit. XXXI. 698/2 It [sc. an efficient shutter] should be adjustable for variable instantaneous and for prolonged or ‘time’ exposures. 1939Emanuel & Dash All-in-One Camera-Bk. 33 It is usual to divide the long series of commonly used exposures into two parts. Exposures of 1/50 or 1/100 second or less belong to the instantaneous group, whereas the slower shutter speeds, such as 1/10 or 1/5 second, and so on, count as time exposures. Ibid., If your hand is reasonably steady you will be able to give an exposure of 1/25 without moving the camera. A picture of this kind, made without the help of a tripod or other fixed support, can be counted as a snap—an instantaneous exposure. 1973B. Jay Victorian Cameraman 57 Instantaneous exposures were not possible when Frith first began his photographic business.
fig.1867Ellis E.E. Pron. i. i. 17 Each written word is, as it were an instantaneous photograph of a living thing.
c. Applied to a gramophone record in which the grooves are made directly by the cutting stylus during recording, and to the making of such records.
1937Electronics Sept. 65/3 (Advt.), Disclube protects the delicate sound impressions in the record groove... A 2 oz. bottle of Disclube will be sent..to any person or firm equipped to make instantaneous recordings. 1949Frayne & Wolfe Elem. Sound Recording xiv. 263 Besides its commercial applications, instantaneous recording finds considerable use in the home and as an adjunct in some of the educational fields, such as voice and music training, although..magnetic recording is becoming a serious competitor in certain fields. Ibid. 270 There is little practical difference between the best instantaneous records and the best pressings..when both are played with good light-weight reproducers.
d. instantaneous (water-)heater = geyser 2.
1935Plumber & Decorator Mar. 57/2 Instantaneous water heaters are of two types—the multi-point, supplying hot water to several taps in different parts of the house; the single-point ‘geyser’ supplying hot water at the place where it is fixed. 1940Chambers's Techn. Dict. 450/2 Instantaneous water-heater. 1959Chambers's Encycl. VII. 258/1 Instantaneous heaters may be multipoint, supplying hot water to a number of taps, or single point for one tap only.
2. Existing at or pertaining to some particular instant. Chiefly in Dynamics, as instantaneous axis, instantaneous centre of rotation.
1837Babbage Bridgew. Treat. App. K. 250 It is to be deduced..from the means of the instantaneous heights of the tide at all intervening periods. 1854Tomlinson tr. Arago's Chem. 131 Its axis of rotation may change every moment; and this multitude of axes..are called the instantaneous axes of rotation. 1886A. G. Greenhill Diff. & Int. Calc. 241, I..is the centre of instantaneous rotation of the right angle. |