The electric railway progress was so great in the United States that about January 1, 1891, there were more than two hundred and forty lines in operation. About thirty thousand horses and mules were replaced by electric power in the single year of 1891. In 1892 the Thomson-Houston interests and those of the Edison General Electric Company were merged in the General Electric Company, an event of unusual importance, as it brought together the two great competitors in electric traction at that date. Other electric manufacturers, chief among which was the Westinghouse Company, also entered the field and became prominent factors in railway extension. In a few years horse traction in the United States on tramway lines virtually disappeared. Many cable lines were converted to electric lines, and projects such as the Boston Subway began to be planned. Not the least of the advantages of electric traction is the higher speed attainable with safety. The comfort and cleanliness of the cars, lighted brilliantly at night, and heated in winter by the same source of energy which is used to propel them, are important factors. All these things, together with the great extension of the lines into suburban and country districts, and the interconnection of the lines of one district with those of another, cannot fail to have a decidedly beneficial effect upon the life, habits, and health of the people. While the United States and Canada have been and still are the theatre of the enormous advance in electric traction, as in other electric work, many electric car lines have in recent years been established in Great Britain and on the continent of Europe. Countries like Japan, Australia, South Africa, and South America have also in operation many electric trolley lines, and the work is rapidly extending. Most of this work, even in Europe, has been carried out either by importation of equipment from America, or by apparatus manufactured there, but following American practice closely. The bulk of the work has been done with the overhead wire and under-running trolley, but there are notable instances of the use of electric conductors in underground slotted conduits, chief of which are the great systems of street railway in New York City. In Chicago the application of motor-cars in trains upon the elevated railway followed directly upon the practical demonstration at the World’s Fair of the capabilities of third-rail electric traction on the Intramural Elevated Railway, and the system is rapidly extending so as to include all elevated city roads. A few years will doubtless see the great change accomplished.