HEAVISIDE, OLIVER (1850-1925), English physicist, was born in London on May 13, 1850. He was employed by the Great Northern Telegraph Company, Newcastle. Increasing deafness forced him to retire in 1874, when he went to live in Devonshire and devoted himself to theoretical investigations on electricity. Heaviside had some difficulty in getting his papers accepted for publication, probably because he made use of un usual methods of his own in solving his problems. Consequently, in 1892 he published his collected papers in two volumes under the title of Electrical Papers. In these papers he dealt with the theoretical aspect of a number of practical problems, such as quadruplex and multiplex telegraphy, electrostatic and electro magnetic induction between parallel wires, and the high frequency resistance and inductance of a concentric main. His work on the theory of the telephone has made long distance telephony prac ticable. His Electromagnetic Theory also dealt with a number of important problems. He worked out the theory of an electric charge moving with uniform velocity, and predicted the change in the mass of such a charge when the velocity is large. He also, independently but shortly after Dr. A. E. Kennelly, of Harvard, suggested the presence of a conducting layer in the upper atmos phere which prevents electromagnetic waves spreading out into space. This layer is now called the Kennelly-Heaviside layer. He died at Torquay on Feb. 3, 1925.