Dictionary of National Biography, 1885-1900/Hearder, Jonathan
HEARDER, JONATHAN (1810–1876), electrician, born at Plymouth in 1810, was well known as a popular lecturer throughout the west of England. Though nearly blind, owing to an accident when experimenting in his youth with a fulminating compound, he acquired a thorough knowledge of practical chemistry and electricity, and was for many years intimately associated with Sir William Snow Harris [q. v.] in his researches. Hearder devised several improvements in connection with the induction coil and the application of electricity to medical purposes. He also invented and patented a sub-oceanic cable, which proved to be almost identical with that subsequently chosen for transatlantic telegraphy. Another invention was a thermometer for lead soundings at sea which should indicate the depth of water by its pressure. Hearder's attainments, however, were not exclusively scientific, and his success as a lecturer was due not only to his knowledge of facts, but to his skill as an experimenter and his genial manner. He took a special interest in the Plymouth Institution, and had an excellent knowledge of local antiquities and history. He acted for many years as electrician to the South Devon Hospital. Hearder died in Plymouth of a paralytic attack on 16 July 1876.
[Ann. Reg. for 1876; Athenæum, July 1876; Plymouth Gazette, 19 July 1878.]