| 释义 |
diameter|daɪˈæmɪtə(r)|
Also 4–6 diametre.
[a. OF. dia-, dyametre (13th c. in Littré; mod.F. diamètre), ad. L. diametrus, -os, a. Gr. διάµετρος (sc. γραµµή line) diagonal of a parallelogram, diameter of a circle, f. διά through, across + µέτρον measure.]
1. Geom. A straight line passing through the centre of a circle (or sphere), and terminated at each end by its circumference (or surface). Hence extended to a chord of any conic (or of a quadric surface) passing through the centre; and further, to a line passing through the middle points of a system of parallel chords (or through the centres of mean distances of their points of intersection with the curve), in a curve of any order.
b. The diagonal of a parallelogram. (obs.)
c. gen. A line passing from side to side of any body through the centre.
1387Trevisa Higden (Rolls) VII. 71 Þe dyameter [of] a figure [is] þe lengest even lyne þat is devysed þerynne, take who þat may. 1551Recorde Pathw. Knowl. i. Def., And all the lines that bee drawen crosse the circle, and goe by the centre, are named diameters. 1551― Cast. Knowl. (1556) 18 Euery right lyne that passeth from side to syde in a globe, and toucheth the centre, is aptely called a diameter. 1635N. Carpenter Geog. Del. i. v. 110 All the Diameters of the world concurre, and cut one the other in the Center. 1660Barrow Euclid i. Def. xxxvi, In a parallelogram, when a diameter..[is] drawn. 1726–7Swift Gulliver ii. iv. 129, I paced the diameter and circumference several times. 1796Hutton Math. Dict. s.v., Diameter, of any Curve, is a right line which divides two other parallel right lines, in such manner that, in each of them, all the segments or ordinates on one side, between the diameter and different points of the curve, are equal to all those on the other side. This is Newton's sense of a Diameter. But, according to some, a diameter is that line, whether right or curved, which bisects all the parallels drawn from one point to another of a curve. 1831R. Knox Cloquet's Anat. 35 The Thorax..is measured by means of certain ideal lines, named its diameters, which pass from the sternum to the vertebral column, or from one side to the other. All the diameters are greater below than above. 1885C. Leudesdorf Cremona's Proj. Geom. 217 If any number of parallel chords of a conic be drawn, the locus of their middle points is a straight line..This straight line is termed the diameter of the chords which it bisects.
¶ In some editions of Lydgate's Balade of our Ladie 87 ‘dyametre’ is misprinted for ‘dyamaunt’: see Skeat Chaucerian Pieces 278, MacCracken Minor Poems of Lydgate I. 258.
2. The transverse measurement of any geometrical figure or body; the length of a straight line drawn from side to side through the centre, esp. of a circle or body of circular, spherical, or cylindrical form; width; thickness.
c1391Chaucer Astrol. ii. §38 Let this pyn be no lengere than a quarter of the diametre of thi compas. 1557Recorde Whetst. iv. b, A Gonne of sixe inches diameter in the mouthe. a1635Corbet Poems 192 The just proportion..Of the diameter and circumference. 1703Moxon Mech. Exerc. 273 A Chimny, whose Diameter between the Jambs is eight feet. 1774Goldsm. Nat. Hist. (1776) VIII. 106 [A wasp] boring a hole..not much wider than the diameter of its own body. 1812–6J. Smith Panorama Sc. & Art I. 312 The power and the weight will balance each other, when the power bears the same proportion to the weight that the diameter of the axis bears to the diameter of the wheel. 1868Lockyer Elem. Astron. ii. (1879) 39 The diameter of the Sun is 853,380 miles.
†b. ellipt. with numeral expressions: = of (such a) diameter, or = in diameter (4 a). Obs.
1663Gerbier Counsel 69 Balls twelve inches Diameter. 1718Lady M. W. Montagu Let. to C'tess Bristol 10 Apr., The dome..is said to be one hundred and thirteen feet diameter. 1825J. Nicholson Operat. Mechanic 191 Some..were not more that 3½ inches diameter.
†c. Geom. The length of the diagonal of a parallelogram. Obs.
†d. Arith. A number that is the square root of the sum of the squares of the two factors of a diametral number (and hence may be represented by the diagonal of a rectangle whose sides are proportional to these factors, the rectangle itself representing the ‘diametral number’). Obs.
1557Recorde Whetst. D j, 17 is the diameter to that diametralle number 120 [= 8 × 15]. Ibid., 5 is the diameter of that platte forme.
e. Arch. The transverse measurement of a column at its base, taken as a unit of measurement for the proportions of an order.
1604Drayton Owle 629 Of Columnes the Diameters doth tell. 1727–51Chambers Cycl. s.v., Diameter of a Column, is its thickness just above the base. From this the module is taken, which measures all the other parts of the column. Diameter of the Diminution, is that taken from the top of the shaft. Diameter of the Swelling, is that taken at the height of one-third from the base. 1842–76Gwilt Archit. iii. i. §2556 Vitruvius in this order [the Tuscan] forms the columns six diameters high, and makes their diminution one quarter of the diameter. 1850J. Leitch Müller's Anc. Art §54 The columns in the temple of Ephesus were eight diameters high.
f. As a unit of linear measurement of the magnifying power of a lens or microscope. (Cf. also quot. 1665 in 4 a.)
1856Emerson Eng. Traits, First Visit Wks. (Bohn) II. 3 His microscopes, magnifying two thousand diameters.
g. Whole extent from side to side or from end to end.
1602Shakes. Ham. iv. i. 41 [Slander], whose whisper o'er the world's diameter, As level as the cannon to his blank, Transports his poison'd shot. c1645Howell Lett. I. vi. xxxviii. 261, I have traversed the Diameter of France more than once.
†3. The diametrical or direct opposite; contrariety, contradiction. Also ellipt. = in diameter 4 b. Obs.
1579J. Stubbes Gaping Gulf A v, What a diameter of religion were it for vs dwelling among Christians, to admit from ouer sea, the sons of men in mariage? 1661Glanvill Vanity of Dogmatizing 76, I shall not undertake to maintain the Paradox, that stands diameter to this almost Catholic opinion.
4. Phrases. in diameter.
a. lit. in sense 2 (with numerals, etc.): In measurement across through the centre; in width or thickness. (Formerly also in the diameter.)
1577Dee Relat. Spir. i. (1659) 356 A trunk of fire, which..seemeth to be 4 foot over in the Diameter. 1665Phil. Trans. I. 60 It would magnifie but 600 times in Diameter. a1719Addison Italy (T.), The bay of Naples..lies in almost a round figure of about thirty miles in the diameter. 1858Hogg Veg. Kingd. 110 The fruit hangs from the tree [baobab] by a stalk two feet long and an inch in diameter.
†b. Diametrically, directly (with words denoting opposition or contrariety); in direct opposition. [After Gr. ἐκ διαµέτρου ἀντικεῖσθαι to lie diametrically opposite.] (Usually fig.) Also (in lit. sense) by a diameter. Obs. (Cf. diametrical 2, 2 b.)
1543Traheron Vigo's Chirurg. vi. i. 181 By flebothomie on the contrary syde by a diameter. 1598B. Jonson Ev. Man in Hum. iv. vii, To come to a publike schoole..it was opposite (in diameter) to my humour. 1643Milton Divorce ii. xxi. (1851) 122 To hinder..those deep and serious regresses of nature..is in diameter against both nature and institution. 1643Sir T. Browne Relig. Med. i. §3 To stand in diameter and swords point with them. Ibid. i. §51 It is not worthy to stand in diameter with Heaven.
†c. in a diameter: in a direct line, directly. Obs. (Cf. diametrically 3.)
a1681J. Lacy Sir H. Buffoon i. Dram. Wks. (1875) 228 Deriving our pedigree in a diameter from the best blood of Europe.
Hence diˈametered a., of a (specified) diameter.
1707Sloane Jamaica I. 57 A two or three inch long diameter'd broad woody pedestal. Ibid. 63 A foot diameter'd, large, broad, roundish root. |