| 释义 |
‖ tympanum|ˈtɪmpənəm|
Pl. tympana.
[L. tympanum drum, wheel for raising weights, face of pediment, etc., a. Gr. τύµπανον drum, f. root of τύπτειν to strike, beat.]
1. A drum or similar instrument, as a tambourine or timbrel (esp. ancient); also, the stretched membrane of a drum, a drum-head.
1675Covel in Early Voy. Levant (Hakl. Soc.) 203, 6 Drumes, 4 trumpets, 2 kettle-drumes, and 4 tamburs (or tympanums) like sives cover'd with parchment at bottome. 1830Hobart Town Almanack 92 The little tympanums which the Chinese hawk about the streets to amuse children. 1847J. Leitch tr. C. O. Müller's Anc. Art §395 (1850) 520 She [Cybele] is recognised by the crown of flowers, the tympanum as a symbol of her enthusiastic worship, and the car yoked with lions. 1908Sir H. Johnston Grenfell & Congo I. xvi. 394 The slipping of his fingers down the cane set up a vibration of the tympanum of the drum.
2. Anat. The drum of the ear (med.L. tympanum auris, Albertus Magnus c 1255); the middle ear, consisting of a cavity in the temporal bone, filled with air, separated from the outer auditory canal by the tympanic membrane (membrana tympani) and from the inner ear by the membranes of the fenestra ovalis and fenestra rotunda, and containing the chain of small bones (auditory ossicles), or in lower vertebrates the single bone (columella), by which sound-vibrations are conveyed to the inner ear. Also often applied to the tympanic membrane simply.
In insects, a similar membrane with connected parts, in some cases supposed to constitute an organ of hearing (cf. quot. 1887 s.v. tympanal a.).
1619Purchas Microcosmus ix. 99 The passage auditorie being anfractuous, lest the Tympanum should by directer incursions be endangered. 1691Ray Creation ii. (1692) 38 At the end of this hole is a Membrane..stretched like the head of a Drum, and therefore by Anatomists called also Tympanum. 1709Steele Tatler No. 47 ⁋3, I recited some Heroick Lines..which operated so strongly on the Tympanum of his Ear [etc.]. 1726Monro Anat. Bones (ed. 3) 97 The Cavity of the Ear, called Tympanum. 1840G. V. Ellis Anat. 282 The tympanum or middle ear is a circular space, situated in the base of the petrous portion of the temporal bone..; a chain of small bones crosses the cavity, to convey the undulations of sound to the labyrinth that is internal to it. 1856Todd & Bowman Phys. Anat. II. 63 The tympanum..communicates..with the cavity of the throat through..the Eustachian tube, whereby air has a free access into the tympanum. 1868Duncan Figuier's Insect W. Introd. 6 The membrane..represents a trace of the tympanum which exists among the higher animals. 1871Rossetti Poems, Dante at Verona xlvi, A Jester,..a ribald mouth to shout In Folly's horny tympanum Such things as make the wise man dumb. 1880Günther Fishes 116 A tympanum, tympanic cavity [etc.] are..absent in..fishes.
b. Ornith. (a) Each of the two inflatable air-sacs at the sides of the neck in certain birds, as grouse. (b) Applied to the bony labyrinth at the base of the trachea in certain species of duck, having resonant membranes in its walls.
1873Coues Birds N.W. (1874) 416 An illy-defined white area on each side of the neck, over the tympanum. 1896Newton Dict. Birds 984 [In] the males of many..Anseres, some 6 or 8 of the lowest rings [of the trachea are] fused together..forming..the bulba ossea or labyrinth... This..becomes very complicated in the group of ‘Diving Ducks’, forming in many cases a tympanum, whose bony walls are fenestrated and the spaces filled with a resonant membrane.
3. Arch.
a. The die or cubical portion of a pedestal.
b. The vertical recessed face of a pediment, often adorned with sculpture.
The sense ‘panel of a door’, given in the Glossary to Gwilt's Encycl. Archit., and thence in mod. Dicts., is app. only Latin (Vitruvius).
1658tr. Porta's Nat. Magic xix. v. 393 And in the upper surface of the Tympanum, bore the basis quite through with a little pipe, which enters into the hollow of the Tympanum. 1680Evelyn Diary 18 Apr., The tympanum or gabal at the front [of Cashiobury] is a bass-relievo of Diana hunting. 1723Chambers tr. Le Clerc's Treat. Archit. I. 111 The Tympanum is either Triangular or Circular. 1841W. Spalding Italy & It. Isl. I. 161 The statues..which filled the tympana, or triangular spaces of the pediments at both ends of the temple. a1878Sir G. G. Scott Lect. Archit. (1879) I. 166 In the tympanum are sculptured scenes from Scripture history.
4. Mech.
†a. The barrel of a capstan or similar apparatus for raising weights (? only Latin). Obs.
b. A kind of wheel (originally drum-shaped) with curved radial partitions, used for raising water.
c. A hollow wheel turned by two or more persons walking inside it, and communicating motion to a machine (Cent. Dict. 1891).
1704J. Harris Lex. Techn. I, Tympanum, in Mechanicks, is a Cylinder, but larger and shorter than the common Axis or Cylinder,..and..usually placed upon that Axis, and is much the same with the Peritrochium, which is a kind of Wheel..in whose Circumference are Staves or Levers to turn the Axis easily about, in order to raise the Weight required. 1875Knight Dict. Mech., Tympanum, 1. An ancient form of wheel for elevating water... The Roman form of the tympanum is described by Vitruvius,..and was derived from Egypt... The tympanum, under the name of the scoop-wheel, is much used in the drainage of the fens in the East of England.
5. Bot. A membrane stretching across the mouth of the spore-case in some urn-mosses.
1832Lindley Introd. Bot. 201 Sometimes one membrane only remains,..stretching across the orifice of the theca, which is closed up by it; this is sometimes named the tympanum. |