The modern overhead trolley, or under-running trolley, as it is called, seems to have been first invented by Van Depoele, and used by him in practical electric railway work about 1886 and thereafter. The universality of this invention for overhead supply marks the device as a really important advance in the art of electric traction. Van Depoele was also a pioneer in the use of an underground conduit, which he employed successfully in Toronto in 1884. The names of Edward M. Bentley and Walter H. Knight stand out prominently in connection with the first use of an underground conduit, tried under their plans in August, 1884, at Cleveland, on the tracks of the horse-railway company. We have barely outlined the history of the electric-motor railway up to the beginning of a period of wonderful development, resulting in the almost complete replacement by electric traction of horse traction or tramway lines, all within an interval of scarcely more than ten years. The year 1888 may be said to mark the beginning of this work, and in that year the Sprague Company, with Frank J. Sprague at its head, put into operation the electric line at Richmond, Virginia, using the under-running trolley. Mr. Sprague had been associated with Edison in early traction work, and was well known in connection with electric-motor work in general. The Richmond line was the first large undertaking. It had about thirteen miles of track, numerous curves, and grades of from three to ten per cent. The enterprise was one of great hardihood, and but for ample financial backing and determination to spare no effort or expenditure conducive to success, must certainly have failed. The motors were too small for the work, and there had not been found any proper substitute for the metal commutator brushes on the motors—a source of endless trouble and of an enormous expense for repairs. Nevertheless, the Richmond installation, kept in operation as it was in spite of all difficulties, served as an object-lesson, and had the effect of convincing Mr. Henry M. Whitney and the directors of the West End Street Railway, of Boston, of the feasibility of equipping the entire railway system of Boston electrically. Meanwhile the merging of the Van Depoele and Bentley-Knight interests into the Thomson-Houston Electric Light Company brought a new factor into the field, the Sprague interests being likewise merged with the Edison General Electric Company. The West End Company, with two hundred miles of track in and around Boston, began to equip its lines in 1888 with the Thomson-Houston plant. The success of this great undertaking left no doubt of the future of electric traction. The difficulties which had seriously threatened future success were gradually removed.