Niagara Falls 



1894 lighting which was not suitable for running the then known 

 Le Sueur motors. The method of electrical distribution for lighting pur- 

 poses that is used in cities is available also for transmission to 

 considerable distances. It consists, as is well known, of a dynamo 

 supplying current at a high voltage to the street lines, and a system 

 of transformers each taking a portion of this current at high 

 voltage and giving in return a current of greater amperage or 

 volume and of lower voltage for house consumption, the object 

 being simply to avoid loss of voltage or pressure by transmitting 

 a heavy current over a light wire. As this may not be quite 

 clear to every reader, it may be as well to say a little more about it. 



The energy of any current is determined by and is equal to 

 the product of two of its properties, its volume or amperage and 

 its pressure or voltage. Letting C represent the amperes and 

 V the voltage, we have that the energy = CV. In passing any 

 current over any wire there is a loss of voltage determined by and 

 equal to the product of two things — i. e., the amperage of the 

 current and the resistance of the wire; so we have loss of 

 voltage = CR. Now, if we have two currents — one, say, of 

 ten amperes and one volt, and the other of one ampere and ten 

 volts — the energy will be the same, or ten watts as it is called. 

 If we pass both through a given resistance, R, we shall have a 

 loss of voltage (= CR) ten times greater in the first than in the 

 second case. But a given loss of voltage amounts to only one 

 tenth as much energy (CV) in the second case with C = one 

 ampere as it does in the first with C = ten amperes, so that with 

 only one tenth the given loss of voltage the energy lost will be only 

 one one-hundredth that lost in the first case. What it amounts to 

 is that the loss in passing a given amount of electrical energy 

 through a given resistance is proportional to the square of the cur- 

 rent, or amperage, and consequently inversely proportional to the 

 square of the pressure, or voltage. 



If, therefore, current is used in a house at fifty volts and trans- 

 mitted to the house at one thousand volts, the loss will be only 

 one four-hundredth as much over a given wire as it would be if 



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