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THE POPULAR SCIENCE MONTHLY. 



Fig. 3. 



-Tandem Locomotive 

 (end view). 



ing, driving-wheels, etc. The locomotive is suspended by two 

 wheels, Q, which have rubber tires. The electridal current pass- 

 ing through the motor drives it at the rate of sixteen hundred to 



seventeen hundred revolutions a minute, 

 and the power is transmitted by the cog- 

 wheels A and B to a second horizontal 

 shaft on which is a chain-wheel, F. A 

 chain going round this wheel, and round 

 two chain-wheels at C, C, causes the two 

 driving-wheels of the locomotive to rotate. 

 Various forms of grip and friction- 

 gearing locomotives have been devised by 

 the staff of the Telpherage Company, but 

 it was found that the simple locomotive 

 represented in the figure could go quite 

 readily up inclines as steep as one foot 

 rise in thirteen ; no grades so steep as this 

 were needed at Glynde, hence the more 

 elaborate machines were not put in use 

 there. Prof. Perry is confident that the 

 simple locomotive would be effective on 

 grades as steep as one in ten, if the rail be kept quite dry. It was 

 found that the weight of the locomotive, which is not much greater 

 than that of one of the loaded skeps, with the aid of the rubber 

 tires produces enough friction on the rail for the propulsion of 

 the train. In the wet season of the year the rubber tires will last 

 only a fortnight, but in dry weather their life is much longer. 

 Still, even on the wettest days the locomotive performs its work 

 quite well. 



It was feared at first that trains near the engine-house would 

 move much faster than those which were farther away. But this 

 difficulty is prevented by an electrical governor attached to each 

 locomotive. In Fig. 4, D is the second shaft, and W W are the two 

 weights of a centrifugal governor, which are held ordinarily in po- 

 sition near the axis by means of the spring S. When the weights 

 fly apart to the dotted positions W and W, they draw the lever 

 into the dotted position and break the metallic contacts at c, so 

 that no electricity can be received by the motor. But no spark is 

 made at c, because, after the contact is broken there, a connection 

 of small resistance is continued for a short time at a, between two 

 carbons, or a piece of carbon and a piece of iron, one of which is 

 compelled by a spring to follow the other for some distance. If 

 the contact be suddenly broken when the motor is making sev- 

 enteen hundred revolutions a minute, the electric current will 

 remain cut off until the speed of the motor has become reduced 

 to about fifteen hundred. The position of the governor on the 



