December 9, 1897] 



NATURE 



123 



then have calculated the heat equivalent of work by 

 dividing the calculated thermal units (which no doubt he 

 would have assumed as being all converted into 

 mechanical effect) by the resultant work expressed in 

 foot-pounds. Manifestly he would, in the latter case, 

 have given too high a heat value to the mechanical effects; 

 just as in his actual reasoning he has given too high a 

 mechanical value to his heat units." 



And then in a footnote : 



" There can be no doubt that it was purely accidental 

 that the latter process has not been adopted by Joule " ! 



If he had happened to make his experiments in this 

 inverse way, the authors go on to say, the law deduced 

 would be " that the heat energy of the universe is 

 becoming every day more and more changed into 

 mechanical energy." 



" Thomson's error was due to his acceptance of Joule's 

 conclusions. Joule, in his turn, arrived at his fallacious 

 conclusions by the double error, . . . and both these 

 philosophers have shared in the fundamental error that 

 ' energy ' is a something which is transferred from one 

 body to another. Thus do we see how fertile an erroneous 

 conception is in producing error. . . . Verily, as Lord 

 Bacon expressed it " — 



Then follows a quotation about the tendency of the 

 human mind to reject contrary instances — not without 

 great and pernicious prejudice — " in order that the 

 authority of those previous conclusions may remain un- 

 shaken." 



But not only do they thus misapprehend matters 

 of real physics : the authors also fail to understand 

 even such simple popular phrases as Tyndall's " Heat 

 a mode of motion," and criticise it as if "mode" 

 meant " result " : saying that if heat were due to 

 motion, then equal weights of different substances 

 falling from equal heights should manifest the same in- 

 crease of temperature (p. 165), and they go on to say that 

 experiments on this point would be desirable. The 

 generation of heat, they say, is due to states or acts of 

 coercion, and in one of the it^w modest sentences to be 

 found in the book they confess, on p. 163, that 



" our own belief is that all bodies while in states of 

 coercion [like compressed air] are constant sources of 

 heating, but that the diffusion is equal to the rate of 

 generation, and hence no sensible increase of tempera- 

 ture can take place." 



Further on they recover from this unusual weakness, 

 stoutly maintaining that what they call Tyndall's view of 

 heat is quite wrong, "since heat is due to arrested motion, 

 not to motion itself," and boldly asserting that the amount 

 of heat generated by bodies falling from a height depends 

 upon their hardness, 



'a quantity of water or mercury falling from a certain 

 height would not generate as much heat as would a like 

 quantity of, say, steel falling from an equal height." 



It would be tedious to follow the authors through their 

 wild statements concerning electricity and magnetism in 

 detail : the following brief e.xtracts must suffice. 



" The gold-leaf electroscope, consisting as it does of 

 glass and metal, will be found to be analogous to an 

 electric machine. Indeed, the principle of the instru- 

 ment is not yet understood, and no attempt has been 

 made to explain it" (p. 211). 



NO. 1467, VOL. 57] 



" The resistance of thin wires is less than the resist- 

 ance of thicker wires of the same material, which is the 

 opposite of what is currently believed to be the case " 

 (p. 222). 



" The total resistance of 6 lbs. of copper, for instance, 

 would be the same whether the 6 lbs. of copper were 

 only a yard in length, with a corresponding diameter, or 

 a mile long and correspondingly thinner." 



" Air is a most powerful electric, and when between 

 the poles of a powerful electro-magnet partakes of the 

 character of a viscous fluid." 



Then follows a reference to the usual well-known ex- 

 periment of moving or spinning copper between the 

 poles, with the following note appended : 



" which shows that air is attracted by powerful magnets 

 and held there with a firm grasp." 



" The distinction between electric and magnetic attrac- 

 tion is arbitrary, and no more philosophic than is the dis- 

 tinction between light and heavy bodies, hot and cold 

 bodies, voltaic electricity and galvanism." 



The distinction usually drawn between conduction and 

 induction is asserted to be spurious. Heat electricity 

 and magnetism are said to be identical, being all excited 

 by friction. Magnetic attraction may just as well be 

 called gravitation, since the only difference is that it is 

 not necessarily in a vertical direction. 



Thus we get led back once more to the subject of 

 gravitation, and Newton's law is replaced by the following 

 foggy statement. 



" Bodies attract each other in proportion to their 

 different states of excitation, in proportion to relative 

 mass, and inversely proportionally to the square of the 

 distance and intervening resistance." 



"The point of attraction of the earth for bodies on its 

 surface cannot be in the centre . . . for that would 

 involve the assumption that the opposite half of the 

 globe . . . exerts a force equal to that of the nearer 

 half." 



" The theory that attraction is proportional to mass is 

 not borne out by facts : attraction on earth is actually 

 less where the diameter of the earth is greatest. If we 

 turn to the heavens matters are even less satisfactory." 



The astronomical determination of the mass of central 

 bodies turns out on their view to be quite illusory. 



With regard to " action at a distance," our philosophers 

 find no difficulty whatever ; they point out that air and 

 water and other matter only obstruct the fall of bodies, 

 wherefore, of course the less there is between bodies 

 the better they can attract. They quote the usual 

 extract from Newton's letter to Dr. Bentley, and add 

 comments 



"in order to show why such luminaries of the human 

 intellect were unable to see what to us seems as plain 

 as the noon-day sun ; and we trust to be able to show 

 the reader that it was again the ignis fatuus of suggestive 

 words and false concepts by which these great intellects 

 were decoyed from the path of philosophy into the 

 quagmire of metaphysical word-quibblings." 



But now, towards the end of the volume, when the 

 Newtonian theory is once more attacked, the authors 

 fail to keep their mantle so strictly down, and the cloven 

 hoof of the familiar old paradoxer becomes at length 

 conspicuous. 



" This fact, that the planets do not fall into the sun 

 notwithstanding the assertion that they mutually attract 



