| 释义 |
sextant|ˈsɛkstənt|
Also formerly in Latin form 6–7 sextans (7 -ance?).
[ad. L. sextant-, sextans, sixth part (of an as, acre, etc.), f. sextus sixth: see -ant.]
†1. The sixth part of the Roman as. Obs.
1601Holland Pliny xxxiii. x. II. 480 That purse..wherein every man put his sextant, i. the sixt part of an As. 1656Blount Glossogr., Sextant, a coin less then that called Quadrant, by the third part.
†2. The sixth part of a circle. Obs.
1596Blagrave Uran. Astrolabe H 2, The Sextans of a circle. 1609― Dyalling 141 Describe the Sextans, A.B.C. 1656J. B. Descr. Carpenters Rule, etc. 137 The Dyal it self is in form of a Quadrant, Sextance, or Circle, according as you please. Ibid. 139. 1730 Bailey (folio), Sextant, with Mathematicians is the 6th Part of a Circle, or an Arch comprehending 60 Degrees.
3. An astronomical instrument resembling a quadrant, furnished with a graduated arc equal to a sixth part of a circle, used for measuring angular distances between objects, esp. for observing altitudes of celestial objects in ascertaining latitude at sea.
Tycho Brahe, Astron. Instaur. Mech. (1602) A 5, states that he gave the name sextans to this instrument.
1628Burton Anat. Mel. ii. ii. iv. (ed. 3) 264 To examine and calculate the motions of the Planets..by those curious helps of glasses, astrolabes, sextantes [1632, sextants], quadrants. 1726Swift Gulliver iii. iii, Stored with great variety of sextants, quadrants, telescopes [etc.]. 1774M. Mackenzie Marit. Surv. 32 Hold the Sextant vertically, and direct the Sight to some Object in the Horizon, or between you and the Sky, under the Sun. 1828Moore Pract. Navig. 156 Hadley's Sextant is constructed on the same principles as the Quadrant; but..the Arch is extended to 120°..; it is also provided with some appendages not generally annexed to a Quadrant. 1860Dickens Lett. (1880) II. 125 His sextant (which is about the size and shape of a cocked hat), on being applied to his eye, entirely concealed him. 1868Lockyer Elem. Astron. §520 If we require to measure simply the angular distance of one celestial body from another, we employ a sextant.
4. Bot. Each of a group of six segment-cells; also attrib.
1875Bennett & Dyer tr. Sach's Bot. 122, 123 The section of the stem now appears as if composed of six cells or sextants, whose walls are placed nearly radially, forming a six⁓rayed star... Hence the walls..are called sextant-walls... The sextant-cells are still further broken up. 1884Bower & Scott De Bary's Phaner. 19 Then follows in each of these the division into alternately dissimilar sextants.
5. Astr. (With capital initial.) The constellation Sextans.
1795Hutton Math. Dict., Sextans, the Sextant, in Astronomy, a new constellation, placed across the equator, but on the south side of the ecliptic. 1875Encycl. Brit. II. 817/1 The constellations added by Hevelius are the following..:―..10. Sextans, The Sextant. |