The present work is an unabridged edition, in three volumes, of a work originally published at London in 1893, 1899, 1912, respectively, to which has been added a foreword by Sir Edmund Whittaker, 'Oliver Heaviside, an Historical Foreword,' and three appendices, as follows. To the first volume, 'The Work of Oliver Heaviside,' by B.A. Behrend. To the third volume, 'Some Unpublished Notes of Oliver Heaviside,' by H.J. Josephs and in addition 'The Heaviside Papers Found at Paignton,' by J.H. Josephs. The first edition of the present work was reissued in 1922 and again in 1925, at London. A second edition, with an introduction by E. Weber, was published at New York in 1950. The present edition is published at New York, in 1971.