172 



KNOWLEDGE ♦ 



[June 1, 1888. 



and in this its ordinary sense I shall use it in these pages " — 

 because " the terra has thus a potential meaning, to depart 

 from which toould render lamjtuige uniiUeUi/jible " ; though, 

 as he quite correctly points out (the remark in no sense 

 i.ffeoting his opinion as to the impropriety of any attempt 

 to alter the technical use of the word "force"), " we must 

 iruard against supposing that we know essentiall}' more of 

 the phenomena by saying they are produced by something " 

 ( force), " which something is only a word derived from the 

 constancy and similarity of the phenomena" {motions of 

 various kinds) we seek to explain by it. 



Assuredly Sir \V. R. Grove would be far from welcoming 

 the proposed limitation of the word " foi-ce " to one-half of 

 its accepted significance, and the substitution of the word 

 " energy " for the other half, with accompanying maltreat- 

 ment of " attraction " and " repulsion " scarce!}' less pain- 

 fully tending to (and suggestive of) bewilderment. 



Professor Tyndall was very sharply, and as I think most 

 unfairly, taken to task for using the word " force " (both in 

 the singular and plural) as Sir W. E. Grove had done. 

 Yet Professor Tait was undoubtedly right in saying that 

 " the sense in which Newton uses the word ' force ' is the 

 sense in which we should continually use it" (if we are 

 professedly using it technically) " if we desire to avoid 

 intellectual confusion." And certainly Tyndall, who re- 

 peatedly distinguishes between attractive and repulsive 

 '• forces," and clearly recognises the correct meaning of 

 "energy" as simply the capacity (potential or active) for 

 doing work, would ha sorely troubled at the thought that 

 any looseness of expression on his part, where his real 

 meaning could not be misunderstood, should have suggested 

 the astounding idea of merging the distinctive word 

 " attraction " into the general word " force," and the 

 equally distinctive word " repulsion " into the word 

 " energy," which (as constantly used in scientific treatises 

 on dynamical physics) is perfectly distinct from all three. 



Professor Huxley, whom I hold to be the most perfect 

 living model of the man of science (because of all men 

 known to me he is the readiest alike to maintain what he 

 considers should be maintained and to concede what he 

 considers should be conceded), used the word "forces" 

 where, as he afterwards noted, the more general term 

 " powers " would have been better. Is he likely, therefore, 

 to rejoice to see the good old word which has now for two 

 centui'ies done the .same office in ten thousand scientific 

 treatises invited to do half duty, and another word of 

 entirely distinct character invited to abandon its own useful 

 office and do the other half of that duty] Far from it. 

 AVith characteristic manliness he goes out of his way (as 

 weaker men v.'ould hold, but such a man as he can spare 

 the extra travel when it seems necessary) to say that he 

 would rather now write " powers " where he formerly wrote 

 " forces." How Mr. Clodd has come to regard this frank 

 admission by Professor Huxley that the word " force " 

 should be limited to its proper use, into support of the 

 entire misuse of that word (and others) I altogether fail to 

 understand. What men like Sir Wm. Thomson (whom 

 Sir R. Grove — rather significantly — calls Thompson), Pro- 

 fessors Cayly, Adams, Sylvester, and their like, would say 

 to the suggestion that the words "Force," "Attraction," 

 "Repulsion," and "Energy" should be shuffled about as 

 Mr. Allen has suggested I can guess, though I would 

 rather not say. Tlie mildest punishment they would 

 intlict — though I fancy it would not be found very easy 

 penance — would be that Mr. Allen sliould suggest some 

 way of expressing the ideas now represented by " Energy," 

 " potential energy," and " kinetic energy " ; for assuredly 

 his new definitions, whether regarded as rigid and definitive 

 or as loose and ill-fitting, would leave these conceptions 



entirely unrepresented. The more severe would suggest 

 that Mr. Allen should revise according to his novel ideas 

 the whole body of scientific literature relating to matters 

 dynamical. The nature of the task may be inferred from 

 the first two steps which would have to be taken. How- 

 would Mr. Allen re-word the two first laws of ISTewton, 

 remembering that, though originally written in Latin, these 

 laws were repeatedly referred to by Newton as worded in 

 English, thus? — - 



I. Everij body ■pe.rseveres in its state of rest or of uniform 

 motion in a riyht line, unless it is comjMlled to change that 

 stale hy forces impressed on it. 



II. The alteration of ^notion is even proportional to the 

 motive FORCE impressed, and is made in the direction of the 

 right line in which that force is impressed. 



ilay I be permitted to present a parable for the benefit 

 of — whomsoever it maj' concern 1 



For centuries the words " trade " and " wealth " (" poten- 

 tial "and "material") had been used in all treatises on 

 Political Economy in the sense in which tliey are still 

 understood. But it chanced that several writers — among 

 them an able theologian, a learned lawyer, and an ex- 

 perienced archaeologist — in writing on their several subjects 

 used the word " trade " where the more general word " com- 

 merce " would have been better, and seemed (but only 

 seemed) to confound the word " mani;factures " with the 

 expression "material wealth." A pedant or two corrected 

 this, though the writers criticised pointed out that no one 

 could misunderstand their meaning. Hearing of this, an 

 entomologist of great acumen as a naturalist and singularly 

 graceful as a scientific writer, but whose studies gave him 

 no actual occasion to write about trade or commerce or 

 manufactures, or political economy generally — who, in fact, 

 rather disliked these subjects — advocated an entire change 

 in business language. Let us hereafter, said he, call all 

 forms of importation trade and all forms of exportation 

 vjealth. ... It was urged that the four good words — 

 — Trade, Import, Export, and Wealth — would all be put to 

 entirely new uses, if the change were adopted ; that the 

 literature of political economy would have to be rewritten ; 

 and that new expressions would now have to be adopted to 

 express what had heretofore been understood by Wealth, 

 Material Wealth, and so forth. One might as well, said 

 one, speaking as in a parable, propose that Dress should 

 signify the Clothing of Men, and Costume the Clothing of 

 Women. Whether the innovator (who had in the mean- 

 time taken to writing fairy tales) was convinced, this de- 

 ponent sayeth not. But the new usage was not adopted^ 

 and it never will be. 



Mr. Grant Allen would do well to test the idea expressed 

 in his privately published pamphlet by preparing a small 

 treatise on some dynamical subject involving all four of 

 those conceptions — " Force," " Energy," " Attraction," and 

 " Repulsion " — respecting which he has been moved to 

 anxiety. Unless I mistake, he would find his rigid and 

 definite meanings perplexingly elastic and confusing. A 

 pamphlet on the motion of a shell moved by the repvdsive 

 action of exploding powder, and travelling in a resisting 

 medium, first against the attractive action of gravity, and 

 afterwards in response to that action, would afl^ord excellent 

 exercise, not only for the writer, but for the reader (if the 

 new nomenclatui'e were consistently adopted), especially if 

 the shell were suffered to explode just before reaching the 

 earth, and the movements of its parts (assumed equal and 

 of given number) were carefully dealt with. Science is 

 entitled to ask that those who suggest new uses for words 

 which have been for centuries used {by Her, at any rate) in 

 determinate ways, should in some such way show the con- 

 venience and value of the new nomenclature, and manifest 



