‖ speculum
(ˈspɛkjʊləm)
Pl. ˈspecula and -ums.
[L. speculum, f. specĕre to look (at), observe. So F. spéculum, It. speculo, specolo, Sp. espéculum.]
1. A surgical instrument of various forms, used for dilating orifices of the body so as to facilitate examination or operations.
Freq. with Latin genitive of the part for which the instrument is used, as speculum oculi, speculum oris, etc.
| 1597 A. M. tr. Guillemeau's Fr. Chirurg. C ij b/1 A Dilatorye of the Eyeliddes, or the Speculum of the Eye. 1671 Phillips, Speculum oris, an Instrument to skrew open the mouth, that the Chirurgion may discern the diseased parts of the throat. 1693 tr. Blancard's Phys. Dict. (ed. 2), Dilatorium, a Chyrurgeon's Instrument, wherewith the Womb or the Mouth is dilated or opened. It is called likewise Speculum, because by it one may see into the Mouth or the Womb. 1752 Smellie Midwifery Introd. p. xlix, He is the first who gives a draught of the Speculum Matricis for dilating the Os Internum. 1800 Med. Jrnl. IV. 103 Permit me to offer the model of a Speculum Oculi, for insertion in the Medical and Physical Journal. 1862 Catal. Internat. Exhib., Brit. II. No. 3552, Specula, an elegant assortment for the eye, ear, vagina, rectum and nose. 1897 Allbutt's Syst. Med. III. 983 Under an anæsthetic the speculum may be of service. |
2. a. A mirror or reflector (of glass or metal) used for some scientific purpose;
† a lens.
| 1646 Sir T. Browne Pseud. Ep. vii. xviii. (1686) 312 Archimedes burnt the ships of Marcellus with Speculums of Parabolical figures. 1666 Boyle Orig. Formes & Qual. (1667) 30 The giving to a large Metalline Speculum a concave figure, would never enable it to set wood on fire. 1756–7 tr. Keysler's Trav. (1760) I. 401 The notes are written in a very small hand,..so that they cannot be easily read without a magnifying speculum. c 1790 J. Imison Sch. Art I. 218 There are four of these concave specula, of different magnifying powers, to be used as objects to be examined may require. 1825 Gentl. Mag. XCV. i. 292/1 On opening it, it was found to contain in the lid a small convex metallic speculum, and in the under-part a larger one. 1860 Faraday Forces Nat. (1874) 186 A single small speculum, no larger than a nut, will send it in any direction we please. 1873 Spon Workshop Rec. Ser. i. 317/1 Place the speculum, face downwards, in a dish. |
| fig. 1826 Kirby & Sp. Entomol. xlvii. IV. 404 The ultimate object intended to be reflected from this great speculum of creation. 1829 I. Taylor Enthus. vi. 146 The few individuals in every age to whom it has happened to live, and act, and speak under the focus of the speculum of history. |
b. spec. A metallic mirror forming part of a reflecting telescope.
| 1704 Newton Optics (1721) 97 Such an Instrument,..if it be six Foot long, (reckoning the length from the Speculum to the Prism, and thence to the Focus T). 1782 J. Edwards in Naut. Almanac (1787) 52 The Springs at the Back of the great Speculum, which are every Moment varying their Elasticity. 1815 J. Smith Panorama Sci. & Art I. 44 It..is susceptible of so exquisite a polish, as to be admirably adapted for the speculums of telescopes. c 1865 Wylde's Circ. Sciences I. 73/2 The speculum is generally made of an alloy composed of variable quantities of copper and tin. 1868 Lockyer Elem. Astron. §481 The largest reflector in the world has been constructed by the late Earl of Rosse; its mirror, or speculum, is six feet in diameter. |
c. transf. A telescope fitted with a speculum.
| 1789 Herschel in Phil. Trans. (1790) LXXX. 10 In hopes of great success with my forty-feet speculum, I deferred the attack upon Saturn till that should be finished. |
† 3. A diagram or drawing.
Obs.—1| 1676 Coley Clavis Astrol. (ed. 2) iii. 674 A Speculum of the Geniture, or Table of the Radiations of the Planets. |
4. Ornith. A lustrous mark on the wings of certain birds;
= mirror n. 6 b.
| 1804 T. Bewick Brit. Birds II. 342 The exterior webs..are glossed with gold green, which forms the speculum or beauty-spot of the wings. 1863 C. St. John Nat. Hist. & Sport Moray 35 The pochard has no speculum or bright bar on the wing. 1871 Darwin Desc. Man I. viii. 291 The beautiful green speculum on the wings is common to both sexes. |
5. = speculum metal (see sense 6 a).
| 1912 Phil. Mag. XXIV. 321 The gold surface was brought into closer proximity to the speculum surface. 1929 Bureau of Standards Jrnl. Res. (U.S.) II. 343 Data are presented on the ultra-violet reflecting power of various metals—beryllium, chromium,..speculum, stellite, and stain-less steel. 1941 Proc. Physical Soc. LIII. 263 It is not without interest to note that speculum has not such a good reflecting power as the three former materials. 1966 McGraw-Hill Encycl. Sci. & Technol. XIII. 650/1 Among special cast bronzes are bell metal..and speculum. |
6. attrib. a. speculum metal, an alloy of copper and tin used for making specula. Also
speculum steel.
| 1796 Phil. Trans. LXXXVI. 438 The composition in common use, which contains the greatest proportion of tin, is called speculum metal. 1807–10 Tannahill Poems (1846) 76 'Twas by the rays' reflected heat, Frae speculum steel. 1818 W. Phillips Outl. Min. & Geol. (ed. 3) 46 If the proportion of tin [to copper] amount to one third, it forms speculum metal, used for reflecting telescopes. 1873 Spon Workshop Rec. Ser. i. 13/1, 2 lbs. copper, 1 lb. tin, 1 oz. arsenic, form a good speculum metal. |
b. speculum forceps (see
quot. 1875).
| 1875 Knight Dict. Mech. 2261/1 Speculum-forceps, long, slender forceps, used for dressing wounds or operating on parts not accessible except through speculums. 1881 Trans. Obstet. Soc. Lond. XXII. 47 The ovum could generally be removed by the administration of ergot and the ordinary speculum forceps. |