376 THE ADDRESSES, LECTURES, ETC., OF 



light to the extent of about 25 per cent, of the total illuminating 

 power required. To provide a larger percentage of electric energy 

 would increase the cost of establishment proportionately ; and 

 that of conductors, nearly in the square ratio of the increase of the 

 district, unless the loss of energy by resistance is allowed to 

 augment instead. 



It may surprise uninitiated persons to be told that to supply a 

 single parish with electric energy necessitates copper conductors of 

 a collective area equal to a rod of eight inches in diameter ; and 

 how, it may be asked, will it be possible under such conditions to 

 transmit the energy of waterfalls to distances of twenty or thirty 

 miles, as has been suggested. It must indeed be admitted that the 

 transmission of electric energy of such potential (200 volts) as is 

 admissible in private dwellings would involve conductors of im- 

 practicable dimensions, and in order to transmit electrical energy 

 to such distances, it is necessary to resort in the first place to an 

 electric current of high tension. By increasing the tension from 

 200 to 1,200 volts the conductors may be reduced to one-sixth 

 their area, and if we are content to lose a larger proportion of the 

 energy obtained cheaply from a waterfall, we may effect a still 

 greater reduction. A current of such high potential could not be 

 introduced into houses for lighting purposes, but it could be 

 passed through the coils of a secondary dynamo-machine, to give 

 motion to another primary machine, producing currents of low 

 potential to be distributed for general consumption. Or secondary 

 batteries may be used to effect the conversion of currents of high 

 into those of low potential, whichever means may be found the 

 cheaper in first cost, in maintenance, and most economical of 

 energy. It may be advisable to have several such relays of energy 

 for great distances, the result of which would be a reduction of the 

 size and cost of conductor at the expense of final effect, and the 

 policy of the electrical engineer will, in such cases, have to be 

 governed by the relative cost of the conductor, and of the power at 

 its original source. If secondary batteries should become more 

 permanent in their action than they are at the present time, they 

 may be largely resorted to by consumers, to receive a charge of 

 electrical energy during the daytime, or the small hours of the 

 night, when the central engine would otherwise be unemployed, 

 and the advantage of resorting to these means will depend upon 



