42 ABSOLUTE ELECTRIC MEASUREMENT. 



taken subsequently. Of this he says, in his 8th letter : " The 

 difficulty, if not impossibility, of understanding experiments, 

 and comparing them with one another, arises, in general, 

 from incomplete description of apparatus, and from the 

 arbitrary and vague numbers which are made to characterise 

 electric currents. Such a practice might be tolerated in the 

 infancy of the science, but in its present state of advance- 

 ment greater precision and propriety are imperatively 

 demanded. I have, therefore, determined for my own part 

 to abandon my old quantitative numbers, and to express 

 my results in the basis of a unit which shall be at once 

 scientific and convenient. That proposed by Dr. Faraday 

 is, I believe, the only standard of this kind which has been 

 suggested. His discovery of the definite quantity of 

 electricity, associated with the atoms or chemical equiva- 

 lents of bodies, has induced him to use the voltameter as a 

 measure, and to propose that a hundredth part of a cubic 

 inch of the mixed gases forming water should constitute a 

 degree. There can be no doubt that this system would 

 offer great advantages to the experimenter in somes cases,, 

 and when the Ohm instrument is employed. However, as 

 I am not aware that it has been used in the researches of 

 any electrician, not excepting those of Faraday himself, I 

 do not hesitate to advance what I think more appropriate 

 as well as more generally advantageous. It is thus simply 

 stated " : — 



I. "A degree of static electricity is that quantity which is 

 just able to decompose nine grains of water. 2. A degree of 

 current electricity is the same amount propagated during each 

 hour of time. 3. Where both time and length of conductor 

 are elements, as in electro-dynamics, a degree of electric 

 force , or of electro-momentum, is indicated by tlie same- 



