| 释义 |
frustum|ˈfrʌstəm|
Pl. -a, -ums. Also erron. 7–9 frustrum.
[a. L. frustum piece broken off.]
1. Math. The portion of a regular solid left after cutting off the upper part by a plane parallel to the base; or the portion intercepted between two planes, either parallel or inclined to each other.
1658Sir T. Browne Gard. Cyrus iii. 57 In the parts thereof [plants] we finde..frustums of Archimedes. 1669Phil. Trans. IV. 960 The Axis of a Pyramid..and of a Figure of different Bases, which he calls a Frustrum of a Prisme. 1706W. Jones Syn. Palmar. Matheseos 265 The..Frustrums of Spheres, cut by parallel Planes, are equal to the corresponding Surfaces of the Sphere's Circumscr. Cylinder. 1779Forrest Voy. N. Guinea 49 We could see within the straits a hill with a flat top, like what is called the frustum of a cone. 1812–6Playfair Nat. Phil. II. 291 This proposition is easily proved of pyramids, and frusta of pyramids, of which the solid angle is indefinitely small. 1828J. M. Spearman Brit. Gunner (ed. 2) 378 The difference between the two piles thus found will be the number in the frustum or incomplete pile. 1860Maury Phys. Geog. Sea iv. §218 We may..liken this belt of winds which encircles the earth.. to the frustum of a hollow cone.
b. Applied to the sections of the shaft of a column.
1835Willis Pencillings II. xl. 23 We were directed to it by thirteen or fourteen frustra of enormous columns. 1850J. Leitch tr. Müller's Anc. Art §286. 316 A truncated pillar, or frustum of a column.
2. gen. A portion or fragment of anything material or immaterial. rare.
1721Bailey, Frustum, a Fragment, a broken Piece. a1733R. North Examen iii. viii. (1740) 624 This Frustum of a Libel is grafted into his pious History. 1812Crabbe T. in Verse vii. Wks. 1834 IV. 288 She minced the sanguine flesh in frustrums fine. 1812Knox & Jebb Corr. II. 94 What I would deprecate is, putting into people's hands the frusta of a system. |