Part 312

Pope.

(b) A similar instrument the blades of which are extensions of a curved spring, -- used for shearing sheep or skins. (c) A shearing machine; a blade, or a set of blades, working against a resisting edge.

2. Anything in the form of shears. Specifically: (a) A pair of wings. [Obs.] Spenser. (b) An apparatus for raising heavy weights, and especially for stepping and unstepping the lower masts of ships. It consists of two or more spars or pieces of timber, fastened together near the top, steadied by a guy or guys, and furnished with the necessary tackle. [Written also sheers.]

3. (Mach.) The bedpiece of a machine tool, upon which a table or slide rest is secured; as, the shears of a lathe or planer. See Illust. under Lathe.

Rotary shears. See under Rotary.

Shear"tail` (?), n. (Zoöl.) (a) The common tern. (b) Any one of several species of humming birds of the genus Thaumastura having a long forked tail.

Shear"wa`ter (?), n. [Shear + water; cf. G. wassersherer; -- so called from its running lightly along the surface of the water.] (Zoöl.) Any one of numerous species of long-winged oceanic birds of the genus Puffinus and related genera. They are allied to the petrels, but are larger. The Manx shearwater (P. Anglorum), the dusky shearwater (P. obscurus), and the greater shearwater (P. major), are well-known species of the North Atlantic. See Hagdon.

Sheat"fish` (?), n. [Cf. dial. G. scheid, schaid, schaiden.] (Zoöl.) A European siluroid fish (Silurus glanis) allied to the cat-fishes. It is the largest fresh-water fish of Europe, sometimes becoming six feet or more in length. See Siluroid.

Sheath (?), n. [OE. schethe, AS. scð, sceáð, scð; akin to OS. skðia, D. scheede, G. scheide, OHG. sceida, Sw. skida, Dan. skede, Icel. skeiðir, pl., and to E. shed, v.t., originally meaning, to separate, to part. See Shed.] 1. A case for the reception of a sword, hunting knife, or other long and slender instrument; a scabbard.

The dead knight's sword out of his sheath he drew.

Spenser.

2. Any sheathlike covering, organ, or part. Specifically: (a) (Bot.) The base of a leaf when sheathing or investing a stem or branch, as in grasses. (b) (Zoöl.) One of the elytra of an insect.

Medullary sheath. (Anat.) See under Medullary. -- Primitive sheath. (Anat.) See Neurilemma. -- Sheath knife, a knife with a fixed blade, carried in a sheath. -- Sheath of Schwann. (Anat.) See Schwann's sheath.

Sheath"bill` (?), n. (Zoöl.) Either one of two species of birds composing the genus Chionis, and family Chionidæ, native of the islands of the Antarctic seas.

They are related to the gulls and the plovers, but more nearly to the latter. The base of the bill is covered with a saddle- shaped horny sheath, and the toes are only slightly webbed. The plumage of both species is white.

Sheathe (?), v. t. [imp. & p. p. Sheathed (?); p. pr. & vb. n. Sheating.] [Written also sheath.] 1. To put into a sheath, case, or scabbard; to inclose or cover with, or as with, a sheath or case.

The leopard . . . keeps the claws of his fore feet turned up from the ground, and sheathed in the skin of his toes.

Grew.

'T is in my breast she sheathes her dagger now.

Dryden.

2. To fit or furnish, as with a sheath. Shak.

3. To case or cover with something which protects, as thin boards, sheets of metal, and the like; as, to sheathe a ship with copper.

4. To obtund or blunt, as acrimonious substances, or sharp particles. [R.] Arbuthnot.

To sheathe the sword, to make peace.

Sheathed (?), a. 1. Povided with, or inclosed in, sheath.

2. (Bot.) Invested by a sheath, or cylindrical membranaceous tube, which is the base of the leaf, as the stalk or culm in grasses; vaginate.

Sheath"er (?), n. One who sheathes.

Sheath"fish` (?), n. (Zoöl.) Same as Sheatfish.