676 



RAILWAYS, ELECTRIC. 



animal forming a cross-circuit to the conduct- 

 ors. As, for the economical working of an elec- 

 tric railway, currents of high tension are neces- 

 sary, this danger would be too great in such 

 situations to tolerate such a disposition of the 

 conductors. In the ordinary railway this feat- 

 ure would be of little consequence, as the 

 track is not exposed to the public except at 

 the crossing of roads, and this can be readily 

 provided for. The leakage would be, however, 

 in this case prohibitory of the use of these rails 

 in this way. Professsors Ayrton and Perry 

 have modified the two-rail system in such a 

 way as to overcome the difficulty from leak- 

 age, as we shall see below in considering their 

 construction. Other inventors have essayed 

 to overcome it by the use of a third rail or 

 conductor for the outgoing current, utilizing 

 both rails for its return. This conductor may 

 be placed midway between the rails, but ele- 

 vated above them, as used by Siemens, or sunk 

 in a central trough, as in the Edison and Field 

 system, or it may be placed on posts at one 

 side of the rails, the connection then being 

 made between it and the car by a flexible con- 

 ductor. The contact between this latter and 

 the suspended wire is made by means of a lit- 

 tle traveling carriage or trolly. This method 

 of receiving the current would evidently not 

 do for rapidly moving trains, though perfect- 

 ly feasible for street and suburban railways. 



Where high speeds are required, the third rail 

 must be placed so that there may be rigid con- 

 nection between it and the moving car, the 

 current then being taken off by rueans of a 

 rolling or other suitable metallic contact. 



Siemens Railway. The first electric railway 

 was constructed by the firm of Siemens and 

 Halske, of Berlin, at the exhibition in that city 

 in 1879. The line was of two-foot gauge and 

 2,700 feet long. The current was conveyed to 

 the car, which was of sufficient size to carry 

 twenty passengers, by a third rail placed in 

 the center of the track and supported upon 

 insulating wooden blocks. The great success 

 of this experimental line led these constructors 

 to build soon afterward the Lichterfelde line, 

 near Berlin, for actual traffic. This was con- 

 structed on the two - rail system, both rails 

 being placed upon insulating sleepers. The 

 gauge is three feet and the length about a mile 

 and a half. It is worked by two dynamo-ma- 

 chines developing a total of 12 horse-power, 

 and has been in operation since May, 1881. 

 Another line of about the same length has also 

 been built between Charlottenburg and Span- 

 dauer Bock, while a shorter one has been con- 

 structed in Kostverloren Park, near Amster- 

 dam. A short line, something less than half 

 a mile in length, has also been put in opera- 

 tion by the same firm at the Zankerode col- 

 liery in Saxony. The rails are not used in this 



FIG. 1. SIEMENS AND HALSKE'S ELECTRIC ENGINE. 



