a. [f. FRICTION sb. + -AL.] Of or pertaining to friction, moved or produced by friction.
Frictional electricity, electricity developed by friction (see ELECTRICITY 1). Frictional escapement in Watch and Cl.-making, an escapement receiving and transmitting motion by friction. Frictional gearing (-wheels), wheels which transmit motion by friction instead of by teeth. Frictional resistance, the resistance of surfaces due to friction; esp. the resistance to slipping of riveted joints by the contraction of the rivets (Lockwood).
1850. Grove, Corr. Phys. Forces (ed. 2), 23. The divergence of the electrometer, the revolution of the electrical wheel, the deflection of the magnetic needle, are, when resulting from frictional electricity, palpable movements reproduced by the intermediate modes of force, which have themselves been originated by motion.
1870. Tyndall, Lect. Electr., 17. By linking cells together we cause the voltaic current to approach more and more to the character of the frictional current.
1871. Proctor, Sun, iv. 211, note. The frictional impulses of circulating planetary matter in process of subsidence into, and absorption by, the central body.
1879. Thomson & Tait, Nat. Phil., I. I. § 275. A material system can never be brought through any returning cycle of motion without spending more work against the mutual forces of its parts than is gained from these forces, because no relative motion can take place without meeting with frictional or other forms of resistance.
1884. F. J. Britten, The Watch and Clockmakers’ Handbook, 107. The Cylinder, Verge, and Duplex are the best known examples of frictional escapements for watches.
1886. A. Winchell, Walks & Talks Geol. Field, 101. These, continually shifting their positions, as the oceanic tides do, result in daily motions adequate to develop a large amount of frictional heat.
Hence Frictionally adv., ‘as regards friction’ (Cassell, 1882).
