Page:Popular Science Monthly Volume 74.djvu/224

220 100-horse-power capacity, will weigh under direct current system 22,500 pounds and under the alternating system 32,000 pounds, or nearly 50 per cent, excess over the direct-current equipment. For the entire car, however, the excess weight would be only about 12 per cent. The excess in cost would be about 35 per cent. In the case of locomotives the excess weight of the alternating-current equipment is even greater. The New York, New Haven & Hartford alternating locomotive has about the same weight as the New York Central direct-current locomotive, but if compared on the basis of maximum tractive effort the former weighs twice as much. The two locomotives are, however, designed for different service and the comparison is much more favorable to the alternating-current system if based on the continuous capacity. The cost of each of these locomotives is about the same.

Taking a broad view of the situation at present, we find that the direct-current system is already installed and continues to be favored for dense, short-haul traffic, such as is found in city terminals and tunnels, and short suburban service. This is largely due to the greater familiarity with the direct-current motor, to its greater capacity and less cost. It is admitted, however, that this system will not do for through traffic over long distance. The single-phase system possesses marked advantages for long haul, express and passenger service on account of the great saving effected in line conductors and sub-stations. It has the great additional advantage that it can operate on direct currents also and may, therefore, enter terminals already equipped with direct current. There is every indication that the operation of steam railways by electricity will be rapidly extended within the next few years. It appears probable that the single-phase, high-voltage, alternating-current trolley will be used and that for some time direct current will continue to be used in terminals. The tendency, however, will be to abandon direct current in terminals, substituting the high voltage trolley throughout.

The process of change to electricity, however, must necessarily be gradual. The necessary capital investment must be provided for and this will probably be accomplished in any large instance by doing the work piece-meal and charging the cost to renewals. Methods for handling freight traffic have not yet been thoroughly developed. Much freight hauling is done by electricity, but before the bulk of traffic of a through line can be handled some method of multiple operation must be devised for freight trains and the work must be experimented upon by applying the methods at present indicated, to some large project. The standardization of electric railway apparatus is one of the greatest necessities of the present situation. No extensive system would care to operate its trains without the possibility of the exchange of cars with