82 ELECTEIC TRACTION. 



then become a generator and give current to the rails, and its 

 mechanical effects are reversed, so that it brakes tbe train 

 instead of propelling it. 



For controlling the cars a series of levers are worked on 

 the platforms, and a "rheostat" is used for throwing 

 machines into circuit. The last item to be determined is the 

 return of the current to the power-h< use. There are many 

 methods, as have already been pointed out, namely, by earth 

 plates being buried in damp soil and by rail ; but in recent 

 practice the complete metallic return, the same as the over- 

 head wire laid on the top of the sleepers and between the 

 rails, and connected with the latter close to the joints, is 

 pronounced to be satisfactory. 



Of course many objections of an sesthetical nature have 

 been urged against the overhead gearing, but they are more 

 apparent than real, and those who take their stand on such 

 paltry objections I would recommend to look at the telegraph 

 and telephone cables so obtrusively conspicuous in big towns. 

 The telephone people have also complained that the ground 

 return interferes with the successful operation of the tele- 

 phone. The same argument could be brought against electric 

 lighting and telegraphs. The telephone people could meet 

 this chief objection by having a metallic return constructed, 

 the cost of which would be a mere bagatelle. As regards 

 the risk to human life by shock, the working potentiality of 

 500 volts is so low that it is hardly worth considering. 

 Having touched the fringe of the principal objections a brief 

 comparison, pro and con, with other systems of traction will 

 be considered. Traction expenses on horse tramways amount 

 to two-thirds of entire working expenses, to say nothing of 

 its inhumanity ; and as to steam, it is a clumsy but effective 

 method of applying force, and the citizens of Hobart would 

 be wanting in public spirit if they ever permitted steam 

 engines to run along their streets. If a draughtsman sat 

 down and deliberately attempted to design an affront to a 

 decent community he could not have succeeded better than at 

 Sydney. The working expenses of the steam trams there 

 amount to 3s. per train mile. It is now generally admitted 

 that the struggle for existence lies between the cable system 

 and the electric. The cost of the construction of the former 

 in Melbourne amounted to d£34,000 per mile, and 75 per cent, 

 of the available energy is lost by dragging the cable itself, 

 while the whole of the energy can be utilised by the over- 

 head system, excepting a few points percent, due to resist- 

 ance of the current by the overhead wires, to say 

 nothing of numerous mechanical defects. At Min- 

 neaopolis <£80,000 was spent in the purchase of cable 

 plant, but was cast on one side as scrap iron to make way for 



