Industrial Niagara 



transmitted at fifty volts. The advantage that alternating cur- 1894 

 rents have over direct for long-distance transmission is that they 

 may easily be transformed up or down — that is, their voltage 

 at the generating end may be increased (at the expense, of course, 

 of their amperage) and reduced at the consuming end. In point 

 of fact, it is frequently and usually unnecessary to employ such 

 devices at the generating end, for the reason that the generators 

 themselves can work perfectly well at the high voltage requisite 

 to transmit. The objection to using the same high voltage on 

 the consuming machinery is simply that there is more danger of 

 accident with numerous small motors scattered in various places 

 and in the hands of unskilled persons than in a power station 

 containing only two or three highly guarded machines attended 

 by trained operatives. 



In connection with the Niagara Falls work there is the further 

 advantage which the alternating current has over the direct, and 

 that is what may be termed the " flexibility," commercially, of 

 the former. The alternating-current machines operated in parallel 

 at, say, two thousand volts, may have a portion of their current 

 taken from them at that voltage for use in the immediate neigh- 

 borhood and the rest transformed up for distant transmission. 



Lately, and particularly owing to the brilliant work of a young 

 man, a native of Smiljan Lika, a border country of Austria- 

 Hungary, by name Nikola Tesla, there have been devised forms 

 of apparatus, generating as well as consuming, by means of which 

 alternating currents may be economically used for operating 

 motors. To express it very roughly, his method amounts to 

 arranging an armature within a magnetic ring and causing oppo- 

 site magnetic poles to revolve around the ring so as to cause 

 rotation of the armature. 



The operation of these devices is preferably by means of a 

 polyphase alternating current — that is, a flow of electricity hav- 

 ing more than one pulsating current. 



957 



