[ad. med.L. spīrāl-is (Albertus Magnus, a. 1255), whence also F. spiral, It. spirale, Sp. espiral.]
1. Forming a succession of curves arranged like the thread of a screw; coiled in a cylindrical or conical manner; helical: a. In general use.
1551. Recorde, Castle Knowl. (1556), 249. In going betweene the firste degree of Capricorne, and the fyrste of Cancer, he … maketh aboue 182 reuolutions lyke spirall circles.
1668. Wilkins, Real Char., 129. [Shells] more short in the spiral production, considerable for having a Purple juice.
1693. Bentley, Atheism, v. 17. The Spiral, and not Annulary, Fibres of the Intestines.
1712. trans. Pomet’s Hist. Drugs, I. 38. Little, thin, black Seeds, each one having a spiral head.
1781. Cowper, Retirement, 231. As woodbine … In spiral rings ascends the trunk.
1805. Southey, Madoc in Azt., X. 217. Then louder from the spiral sea-shell’s depth Swell’d the full roar.
1825. J. Nicholson, Operat. Mechanic, 246. The spiral tubes in that axle take up the water.
a. 1878. Sir G. Scott, Lect. Archit. (1879), II. 125. The intermediate pier is a round column,… with spiral flutings.
b. Of an ascending course or path.
See also spiral stair in 3.
1794. R. J. Sulivan, View Nat., II. 46. Local lower heat, and proportionate superior cold, causes the rarefaction, which gives the spiral ascent.
1825. Longf., Sunrise on Hills, 18. Where upward … The noisy bittern wheeled his spiral way.
1841. Penny Cycl., XXI. 173/2. An almost circular mountain of considerable height, which is ascended by a spiral road.
1876. T. Hardy, Ethelberta (1890), 264. They paced the remainder of their spiral pathway in silence.
c. With abstract sbs.
1829. T. Castle, Introd. Bot., 234. Losing the spiral character.
1831. Sir J. Sinclair, Corr., II. 264. They have … a species of the pigeon, which fly in a spiral or circular manner, upon one wing.
1860. Emerson, Cond. Life, Beauty, Wks. (Bohn), II. 428. The spiral tendency of vegetation infects education also.
1880. Bessey, Botany, 29. Good examples of ringed, spiral, and reticulated thickening.
fig. 1878. O. W. Holmes, Motley, xvii. 115. That progress is by a spiral movement seems to be a law of Providence.
2. Curving continuously round a fixed point in the same plane at a steadily increasing (or diminishing) distance from it.
a. 1639. Wotton, Reliq. (1651), 231. The Capitall … in a spirall wreathing, which they call the Ionian Voluta.
1656. trans. Hobbes’ Elem. Philos., xvii. 194. That space in the Circle which is without the Spiral Line.
1728. Chambers, Cycl., s.v., The curve B … is called a Spiral Line, and the plain Space contained between the Spiral Line, and the Right Line BA, is called the Spiral Space.
1796. H. Hunter, trans. St.-Pierre’s Stud. Nat. (1799), I. 562. They are disposed in the direction of a spiral line winding from East to West.
1833. Sir C. Bell, Hand (1834), 204. Wherever the sense of feeling is most exquisite, there are minute spiral ridges of cuticle.
1870. F. R. Wilson, Ch. Lindisf., 90. Among some bold spiral curves … a hound-like quadruped is represented.
1895. W. M. Macpherson, Ch. & Priory Monymusk, i. 4. The tracings of the characteristic Celtic spiral ornaments that were engraved on it, are still visible.
3. In various special collocations (chiefly in sense 1), as spiral bit, cam, pump, spring, stair, etc.
Spiral auger, battery, gearing, punch, screw, etc., are described by Knight, Dict. Mech. (1875–84).
1876. Voyle & Stevenson, Milit. Dict., 40/2. *Spiral Bit, a gun implement used for clearing the vents of ordnance when choked.
1855. Ogilvie, Suppl., *Spiral Cam,… the solid cam…, when the ridge is formed spirally on the cone.
1728. Chambers, Cycl., s.v. Screw, Archimedes’s Screw, or the *Spiral Pump, a Machine for the Raising of Water.
1815. J. Smith, Panorama Sci. & Art, II. 120. If we wind a pipe round a cylinder, of which the axis is horizontal, and connect one end with a vertical tube, while the other … is at liberty to turn round…, the machine is called a spiral pump.
1884. Knight, Dict. Mech., Suppl. 842/1. Spiral Pump. A pump that raises its water by a spiral flange or screw, on the principle of the Archimedean screw.
1690. Locke, Hum. Und., III. vi. § 38. Some [watches] have the Balance loose, and others regulated by a *spiral Spring.
1869. Rankine, Machine & Hand-tools, Pl. H 9. 2. The projecting piece, a, is kept up to the slide, b,… by means of the spiral spring and die, h.
1624. Wotton, Archit. (1672), 37. *Spiral, or Cockle Stairs.
1728. Chambers, Cycl., s.v., Spiral Stairs, in Building.
1839. W. Chambers, Tour Holland, 40/1. We were conducted by a spiral stair to the higher part of the tower.
1756–7. trans. Keysler’s Trav. (1760), II. 457. This column, with its *spiral stair-case,… was restored to its former beauty by pope Sixtus V.
1840. Lardner, Geom., 245. Such a spiral surface is the form of spiral staircases, sometimes called geometrical staircases.
1850. Ogilvie, *Spiral-Wheels, in mill work, a species of gearing much used in the textile manufactures.
1883. Gresley, Gloss. Coal-mining, 231. *Spiral worm. A tool for extricating broken boring rods.
b. Bot. in spiral cell, tube, vessel.
1832. Lindley, Introd. Bot., 17. Spiral vessels … are membranous tubes with conical extremities; their inside being occupied by a fibre twisted spirally.
1837. P. Keith, Bot. Lex., 10. A revival of Grew’s first opinion with regard to the function of the spiral tubes.
1861. Bentley, Man. Bot., 15. In some cells the fibre forms are uninterrupted spiral from one end to the other: such are termed spiral cells.
1884. Bower & Scott, De Bary’s Phaner., 157. This is the case in the closely-wound spiral tubes, which show transitional forms to the reticulate.
c. Zool. in specific names (see quots.).
1802. Shaw, Gen. Zool., III. II. 564. Spiral Hydrus…. Yellowish Hydrus with … spirally contorted body.
1861. P. P. Carpenter, in Rep. Smithsonian Instit. 1860, 244. Family Limacinidæ. (Spiral Pteropods.)
d. In attributive combs. (see quots.).
1846. Joyce, Sci. Dial., viii. 18. By means of one of those steel spiral-spring instruments … the fact might be ascertained.
1862. Catal. Internat. Exhib., Brit., II. No. 3500, Patent spiral-spring trusses.
1875. Knight, Dict. Mech., 2276. Spiral-vane Steam-engine. Ibid. (1884), Suppl. 842/1. Spiral Tube Boiler.
4. As adv. = SPIRALLY adv.1
1726. Leoni, Alberti’s Archit., II. 36/1. Those chanels that run spiral about the shaft.
1884. Knight, Dict. Mech., Suppl. 842/1. Plates laid together with something to maintain their distance and then rolled together spiral.
5. Comb., as spiral-coated, -grooved, -horned, pointed adj.; spiral-wise adv.
1728. Chambers, Cycl., The Screw … is a right Cylinder … furrow’d Spiral-wise.
1807. J. E. Smith, Phys. Bot., 200. The sap must soon flow out of those spiral-coated tubes.
1827. G. Higgins, Celtic Druids, p. xlvi. A low spiral-pointed roof of stone.
1864. Athenæum, 5 March, 342/2. Mr. Cuming also exhibited two [pins],… the heads of which are spiral-wise.
1884. Knight, Dict. Mech., Suppl. 842/1. The spiral grooved guide is a wrought-iron tube.
1894. Lydekker, Roy. Nat. Hist., II. 250. The Himalayan markhor … or spiral-horned goat.
