﻿148 Notices respecting New Boohs, 



writing — though, in so doing, he has occasionally allowed his illus- 

 trations and his language to fall into an opposite extreme. 



As everyone knows, Mr. Heaviside has advocated many changes 

 in scientific nomenclature, and has already succeeded in getting 

 some of them adopted. The present volume teems with them ; 

 but he does not appear (p. 34) to expect success for a very large 

 number. 



It is an unfortunate (perhaps an unavoidable) circumstance that, 

 on the appearance of any new branch of science, there is sure to 

 be started a system of nomenclature which, with the advance of 

 knowledge, is soon perceived to be unscientific and misleading. The 

 science of Electricity is far from being an exception to this rule. 

 Its most conspicuous term, Electromotive Eorce, is thoroughly 

 misleading ; aud this term Mr. Heaviside' replaces, very happily, 

 by the term " Yoltage " (p. 26) ; for, that which is usually called 

 the " electromotive force along any path " is, in reality, the line- 

 integral of the [tangential compt. of the] electric force-intensity 

 from the beginning to the end of that path, and this Mr. Heaviside 

 habitually describes as the Yoltage along the path. Analogously, 

 the same integral for the magnetic force-intensity he calls the 

 Gaussage — which, as he takes the trouble to inform us, is " pro- 

 nounced Gowsage, after Gauss (pronounced Gowce) " — this latter 

 to replace the absurd " magnetomotive force." Can we imagine 

 the typical English author taking so much trouble to set us right ? 

 Mr. Heaviside is usually most scrupulously precise and accurate ; 

 but, for a moment, he forgets this characteristic when, at the end 

 of p. 26, he continues : — " The Yoltage or the Gaussage along aline 

 is the sum of the effective electric or magnetic forces along the line : 

 the effective component being merely the tangential component of 

 the real " [i. e. the resultant] " force." He knows well that the 

 sum of such quantities (infinite in number, and each of finite mag- 

 nitude) is infinite. The unskilful " practician " should be told 

 that he is not to take the sum of such components, but the sum 

 obtained by multiplying each of them by the element of length of 

 the curve, and then adding these products together. And is there 

 not a little slip of the same nature at the top of p. 151 (and else- 

 where), where the surface-integral of induction is written 2NB 

 instead of ZNBdS ? 



With regard to another term in very common use with the 

 practicians, viz., " lines of force," Mr. Heaviside is justly severe, 

 more particularly in Yol. II. of his ' Papers ' (p. 328), where he 

 says " It is quite painful to read of magnetic resistance to lines of 

 force.'' The worst of this matter with regard to lines of force is 

 that a line of force, in the strict Euclidian sense of a line (length 

 without breadth) is a mathematical reality with which the mathe- 

 maticians cannot dispense, while the unit tube of force is also a 

 reality, and quite distinct from the line ; so that when the practi- 

 cian talks of the number of lines of magnetic force passing through 

 a given surface, either he employs the notion of tubes while talking 

 of lines, or — and this is, perhaps, what generally happens — he is 



