2 20 THE POPULAR SCIENCE MONTHLY 



mately 100-horse-power capacity, will weigh under direct current sys- 

 tem 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, ISTew 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 com- 

 parison 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 ac- 

 count 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, alter- 

 nating-current trolley will be used and that for some time direct cur- 

 rent 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 tlie 

 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 



