678 



RAILWAYS, ELECTRIC. 



in Fig. 2. The current was conveyed to the 

 motor through a third rail placed between the 

 two others, which was not, however, sunk, as 

 it would have been in a permanent surface 

 structure. The contact between this rail and 

 the car was made by stiff wire brushes press- 



FIG. 2. EDISON AND FIELD'S RAILWAY. 



ing on each side of the rail, which were on the 

 end of a lever reaching down from the car. 



The road was in operation from the 9th to 

 the 23d of June, and made in this time 1,588 

 trips, and carried 26,805 passengers. The 

 speed at which the trains were run was eight 



miles an hour. This could easily be exceeded, 

 but the insecurity of the gallery in which the 

 track was laid prohibited anything above this. 

 Ayrton and Perry's Railway* Realizing the 

 difficulty of insulating the tread rails in a suf- 

 ficiently perfect manner to prevent undue loss 

 by leakage in long lines, and yet desiring to 

 retain the advantages of the two-rail system, 

 Professors Ayrton and Perry set themselves to 

 work to modify the latter system so as to an- 

 swer all the requirements. This they have 

 accomplished in a remarkably simple manner, 

 by the employment of an auxiliary conductor 

 running along one of the rails, between which 

 and the rail electric connection can be made 

 automatically by the moving train. The road 

 is thus divided electrically into sections, only 

 those in the immediate neighborhood of the 

 train at each moment, as it sweeps along, 

 being in circuit. The whole of the tread-rail 

 from which the current is taken by the wheels 

 of the moving car is well insulated from the 

 ground, and the successive sections into which 

 it is divided are also insulated from each other. 

 The auxiliary conductor is in the form of a 

 cable, and can therefore be very perfectly in- 

 sulated, as can also the connections by which 

 it makes contact with the sections of the tread- 

 rail. Any leakage that occurs can therefore 

 take place only from these short sections, and 

 will consequently be inconsiderable. Contact 

 between the cable and the tread-rail may be 

 made in a number of ways. One of these 

 consists in providing a short length of rail, 

 placed so as to be depressed by the wheels of 

 the moving car, and resting upon a corrugated 

 steel disk, which forms the top of the box con- 

 taining the exposed contact of the cable. The 

 flexibility of the disk allows a pin carried by 

 it to make contact with a suitable conducting- 

 piece permanently connected with the cable. 

 The box, which may be of cast-iron, is 

 made tight, so that it is always dry 

 within, where the exposed portion of 

 the conductor is. This box may be 

 bolted to a sleeper at the side of the 

 rail or sunk in the ground, as occasion 

 may require. The cable may be simply 

 insulated with guttu-percha or rubber, 

 or it may be carried in a metal tube 

 filled with paraffine. 



The insulation obtained by this mode 

 of construction is but one of its advan- 

 tages, and that not the most important. 

 Its great advantage lies in the fact that 

 Gcn6lC(ltor it provides an automatic block system, 

 which absolutely prevents a following 

 train from running into the one ahead 

 a block that is determined by the con- 

 ditions of operation, and is not depend- 

 ent upon the vigilance of engine-driver or signal- 

 man. To obtain this result the above-described 

 arrangement is modified somewhat. The road 

 is divided into a number of sections or blocks, 

 a mile or more in length. By the movement 

 of the train the current is put on the section 



