8 REPORT— 1882. 



importance of having the Ohm detei'mined in the most accurate manner 

 possible, and enumerates four distinct methods, all of which should 

 unquestionably be tried with a view of obtaining concordant results, 

 because upon its accuracy will depend the whole future system of 

 measurement of energy of whatever form. 



The word Energy was first used by Young in a scientific sense, and 

 represents a conception of recent date, being the outcome of the labours 

 of Carnot, Mayer, Joule, Grove, Clausius, Clerk-Maxwell, Thomson, 

 . Stokes, Helmholtz, Macquorn-Rankine, and other labourers, who have 

 accomplished for the science regarding the forces in Nature what we owe 

 to Lavoisier, Dalton, Berzelius, Liebig, and others, as regards Chemistry. 

 In this short word Energy we find all the efforts in nature, including 

 electricity, heat, light, chemical action, and dynamics, equally represented, 

 forming, to use Dr. Tyndall's apt expression, so many 'modes of motion.' It 

 will readily be conceived that when we have established a fixed numerical 

 relation between these different modes of motion, we know beforehand 

 what is the utmost result we can possibly attain in converting one form 

 of energy into another, and to what extent our apparatus for effecting 

 the conversion falls short of realising it. The difference between 

 ultimate theoretical effect and that actually obtained is commonly called 

 loss, but, considering that energy is indestructible, represents really 

 secondary effect which we obtain without desiring it. Thus friction in 

 the working parts of a machine represents a loss of mechanical effect, but 

 is a gain of heat, and in like manner the loss sustained in transfen-ing 

 electrical energy from one point to another is accounted for by heat 

 genei'ated in the conductor. It sometimes suits our purpose to augment 

 the transformation of electrical into heat energy at certain points of the 

 circuit, when the heat rays become visible, and we have the incandescence 

 electric light. In effecting a complete severance of the conductor for a 

 short distance, after the current has been established, a very great local 

 resistance is occasioned, giving rise to the electric arc, the highest develop- 

 ment of heat ever attained. Vibration is another form of lost energy in 

 mechanism, but who would call it a loss if it proceeded from the violin of 

 a Joachim or a Norman-Neruda ? 



Electricity is the form of energy best suited for transmitting an effect 

 from one place to another ; the electric current passes through certain 

 substances^the metals — with a velocity limited only by the retarding 

 influence caused by electric charge of the surrounding dielectric, but 

 approaching probably under favourable conditions that of radiant heat 

 and light, or 300,000 kilometres per second; it refuses, however, to pass 

 through oxidised substances, glass, gums, or through gases except when 

 in a highly rarefied condition. It is easy therefore to confine the electric 

 current within bounds, and to direct it through narrow channels of 

 extraordinary length. The conducting wire of an Atlantic cable is 

 such a narrow channel; it consists of a copper wire, or strand of 



