a. and sb. [a. L. quadruplex fourfold, f. QUADRU- + plic-, to fold.]
A. adj. 1. Electric Telegraphy. Applied to a system by which four messages can be sent over one wire at the same time.
1875. Knight, Dict. Mech., 1842/1. Quadruplex Telegraph.
1879. G. Prescott, Sp. Telephone, p. iii. In 1874 Edison invented a quadruplex system for the simultaneous transmission of four communications over the same conductor.
1881. Lubbock, Pres. Addr. Brit. Assoc., in Nature, No. 618. 411. Duplex and quadruplex telegraphy, one of the most striking achievements of modern telegraphy.
2. Engineering. Applied to an engine in which the expansion of the steam is used four times in cylinders of increasing diameter.
1896. Westm. Gaz., 8 May, 10/2. A steamer, fitted with five-crank quadruplex engines.
B. sb. A telegraphic instrument by means of which four simultaneous messages can be sent over the same wire.
Hence Quadruplex v., to make (a telegraph circuit, etc.) quadruplex. Cf. QUAD v.
1887. Brit. Merc. Gaz., 15 June, 43/2. The multiplication of wires soon attracted attention to methods of duplexing and quadruplexing the circuits.
1889. Times (weekly ed.), 29 March, 5/2. If the line is already duplexed…, the addition of the phonophore will quadruplex it.
