.s/A' WILLIAM .sVAJ/A.V.s, F.R.S. 407 



t xjH'iiditiiro for lost effect in the conductor in producing the power 

 to be conveyed. It does not appear that Mr. Deprez has con- 

 sidered the effect of this economic law upon his recent experi- 

 ments. 



Sir William Armstrong, in the year 1878, was probably first to 

 take practical advantage of these suggestions in lighting his house 

 at Cragside during night-time, and working his lathe and saw- 

 bench dm inu- the day, by power transmitted through a wire from 

 a wain-fall nearly a mile distant from his mansion. I have also 

 for some years accomplished the several objects of pumping water, 

 cutting wood, hay, and swedes, of lighting my house, and of carry- 

 ing on experiments in electro-horticulture from a common centre 

 of steam-power. The results have been most satisfactory ; the 

 whole of the management has been in the hands of a gardener and 

 of labourers, who were without previous knowledge of electricity, 

 and the only repairs that have been found necessary were one 

 renewal of the commutators and an occasional change of metallic 

 contact brushes. 



Amongst the numerous other applications of the electrical trans- 

 mission of power, that to electrical railways, first exhibited by 

 I )r. Werner Siemens at the Berlin Exhibition of 1879, has attracted 

 more than ordinary public attention. In it the current produced 

 by a dynamo-machine, fixed at a convenient station and driven by 

 a steam-engine or other motor, was conveyed to a dynamo placed 

 upon the moving car, through a central rail supported upon insu- 

 lating blocks of wood, the two working-rails serving to convey the 

 return current. The line was 900 yards long, of 2-feet-gauge, 

 and the moving car served its purpose of carrying twenty visitors 

 through the Exhibition each trip. The success of this experiment 

 soon led to the laying of the Lichterfelde line, in which both mils 

 were placed upon insulating sleepers, so that the one served for 

 the conveyance of the current from the power station to the 

 moving car, and the other for completing the return circuit. This 

 line has a gauge of 3 feet 3 inches, is 2,500 yards in length, and 

 is worked by two dynamo-machines, developing an aggregate 

 current of 9,000 Watts, equal to 12 HP. It has i.mv been in 

 constant operation since the 16th of May, 1881, and has never 

 failed in accomplishing its daily traffic. A line \ a kilometer in 

 length, but of 4 feet 8| inches gauge, was established at Paris in 



