The successful introduction of the double-cylinder engine was finally accomplished by the exertions of a few engineers, who were at once intelligent enough to understand its advantages, and energetic and enterprising enough to push it forward in spite of active opposition, and powerful enough, pecuniarily and in influence, to succeed. The most active and earnest of these eminent men was John Elder, of the firm of Randolph, Elder & Co., subsequently John Elder & Co., of Glasgow.[97] [97] _Vide_ "Memoir of John Elder," W. J. M. Rankine, Glasgow, 1871. Elder was of Scotch descent. His ancestors had, for generations, shown great skill and talent in construction, and had always been known as successful millwrights. John Elder was born at Glasgow, March 8, 1824, and died in London, September 17, 1869. He was educated at the Glasgow High-School and in the College of Engineering at the University of Glasgow, where, however, his attendance was but for a short time. He learned the trade under his father in the workshops of the Messrs. Napier, and became an unusually expert draughtsman. After spending three years in charge of the drawing-office at the engine-building works of Robert Napier, where his father had been manager, Elder became a partner in the firm which had previously been known as Randolph, Elliott & Co., in the year 1852. The firm commenced building iron vessels in 1860. In the mean time, the experiments of Hornblower and Wolff, of Allaire and Smith, and of McNaught, Craddock, and Nicholson, together with the theoretical investigations of Thompson, Rankine, Clausius, and others, had shown plainly in what direction to look for improvement upon then standard engines, and what direction practice was taking with all types. The practical deductions which were becoming evident were recognized very early by Elder, and he promptly began to put in practice the principles which his knowledge of thermo-dynamics and of mechanics enabled him to appreciate. He adopted the compound engine, and coupled his cranks at angles of 180°, in order to avoid losses due to the friction of the crank-shaft in its bearings, by effecting a partial counterbalancing of pressures on the journals. Elder was one of the first to point out the fact that the compound engine had proved itself more efficient than the single-cylinder engine, only when the pressure of steam carried and the extent to which expansion was adopted exceeded the customary practice of his time. His own practice was, from the first, successful, and from 1853 to 1867 he and his partners were continually engaged in the construction of steamers and fitting them with compound engines.