TRANSACTIONS OF SKCTION G. 771 



their own offices direct to the offices of subscribers, not only in the most distant 

 cities of Great Britain and Ireland, but in Paris and other Continental cities. It 

 is asserted that. such a system would lead to such a rapid increase in the number 

 of subscribers thar an annual subscription of 81. would, even in the largest towns, 

 be sufficient to yield a large profit on its cost, even if all the wires were placed' 

 underground. 



3. Becent Progress in the Use of Electric Motors. 

 By Professor G. Forbes, F.B.S. 



In the application of electric motors I have noticed three directions in which 

 this country needs the testimony of independent and impartial people to assert 

 the value of applications which in sorae other countries are generally adopted. 

 These are: — (1) Electric railways, (ii) Replacing shafting in shops by electric 

 conductors and motors.- (3) Transmitting power to a distance from waterfalls and 

 rivers by electricity. 



Electric liaihcays. — These are thoroughly established in America on the 

 cheapest system, i.e. electricity supplied fram a central station by overhead wires. 

 The extensive adoption of electric tram lines in America, and the small immber in 

 England, is certainly due to the fact that they allow these overhead conductors, 

 and we do not generally do so. The most trustworthy estimates seem to vary- 

 between 418 and 6-00 cents per car mile, including coal, attendance, land and 

 buildings, machinery, line, oil, water, and waste. The question of repairs is serious 

 and must be reduced. Most of the lines adopt spur gearing to reduce the speed 

 from the electric motors to the car axles. They generally use two pinions and 

 two spur wheels. This introduces great friction. It is very generally accepted 

 that 8 horse-power is lost in gear friction, though this seems somewhat incredible, 

 being about 30 per cent. These cars are large, and the motors are of 30 horse- 

 power. This enormous power is absolutely demanded to enable them to start on 

 H gradient with facility, and they do this. There is no crawling about these cars. 

 You feel that there is plenty of power for the work. The noise in the cars used 

 to be very considerable, and tlie injury to watches through magnetisation was at 

 one time an objection. The noise from the gearing, especially when worn, has 

 been deadened by enclosing the motor and gearing in cast-iron boxes. The mag- 

 netisation of watches is prevented by adopting a suitable type of motor. Another 

 source of trouble in motors used to be the brushes, for sparking is hablo to be very 

 violent with the variable load of a tram motor, and the commutators wore awaV 

 rapidly. Since carbon brushes have been introduced this difficulty has entirely- 

 disappeared. 



'J'he loss in double reducing gear and the wear and tear led to all the important 

 companies turning to single reducing gear with rather heavier motors. It would 

 at first appear impossible to go farther, and adopt armatures on the wheel axles 

 without sacrificing the great advantage of gearing, which allows the motors to be 

 independently supported without being subjected to the same shocks as the wheel 

 axles. In spite of this, the Westinghouse Company have introduced a gearless 

 motor, which has strength enough to stand the shocks. But other inventors had 

 the idea of fixing the armature alone on the axle, and supporting the field magnet 

 wholly on springs ; to support it partially on springs is of little value. In this 

 direction the most important and promising plan seems to be that adopted by 

 Eickmeyer and Field. They support the whole motor in guides on springs, and 

 connect the motor axle and the wheel axle by cranks and a coupling bar, the 

 cranks on the right and left sides being at right angles to eacli other. This seems 

 to reduce gearing friction to the minimum, while completely obviating shocks. 



In America spur gearing is almost universal, but in Switzerland the Oerlikon 

 Company are introducing worm gearing, which has been so much approved by 

 Mr. Reckenzaun. Storage batteries have not generally been successful in America, 

 but in some trials have worked very well. 



Replacing Shaftinij by Electricity. — Tlie benefit of replacing shafting bv electric 

 conductors and motors has been thoroughly appreciated in America. Everyone 



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