344 



NATURE 



{March 2, 1876 



preference those which will be useful to the reader if he 

 cares to refer to them." 



This last sentence fully accounts for the character of 

 the work. We may say at once that 'we have not read it 

 through. Our readers will probably soon see why. But 

 we may get a good idea of its contents'by dipping in here 

 and there. Geologists do not require to break a mountain 

 down into road metal in order to discover its structure. 

 The book is by no means a paste and scissors production ; 

 it is evidently the outcome of very considerable mental 

 exertion, not only in reading, but in thinking. But, un- 

 fortunately, the author seems to have accepted as equally 

 trustworthy guides some of the best and most authorita- 

 tive works extant, and along with them some, often 

 of the trashiest, volumes ^of the popular scientific lite- 

 rature of the day. In several, especially of the earlier 

 chapters, the first class of works is mainly referred to, 

 in others the second ; a i&'n chapters are based upon 

 a mixture, consequently the result is extremely curious 

 and instructive, at least to the scientific critic. 

 . As a whole, the work is decidedly superior to any of 

 the popular ones on which part of it is based ; though of 

 course, as they have to a certain extent leavened it, it is 

 in many places not only inaccurate, but positively as- 

 tounding in its misrepresentations. It is quite easy, how- 

 ever, to trace in each case the more extraordinary 

 blunders to their popular scientific source. 



Recent British popular scientific works, at least since 

 we have lost such masters as Faraday and Herschel, 

 have, in general, one or other of two marked charac- 

 teristics. The honest but ignorant man, too ignorant to be 

 aware of his own ignorance, complacently and in good 

 faith writes preposterous nonsense. Our author has 

 wisely let him alone. 



Other quasi-scientific men are acute enough to know, 

 perhaps even to admit to themselves (but only under the 

 strictest seal of secrecy) their own ignorance. Some- 

 times they may condescend so far from their pedestals as 

 to seek assistance from those who are really competent 

 to give it, but even then they do not save themselves. 

 The true critic easily perceives by a single loose word or 

 phrase which such writers cannot refrain from adding to 

 the accurate periods of their mentor (if only to save their 

 own consciences on the question of originality) the true 

 state of the case. 



When the quasi-scientific writer feels diffidence in 

 asking assistance, he gets out of his difficulty by adopting 

 what has been well called the " cuttle-fish dodge," and 

 bewilders his readers by squirting in their faces a cloud 

 of inky verbiage. Our author has trusted too implicitly 

 to /«';«. 



Our readers must now have a notion of what seems 

 to us, at least, the character of this book. The style 

 is clear and good, and many of the incidental re. 

 marks and comments are happy. The early chapters, 

 referring as they do mainly to subjects little treated by 

 the modern popular science writers, are, as a rule, very 

 much superior to the later ones, and in many places may 

 be not merely passed as satisfactory, but even highly 

 commended. For instance, the discovery of the law of 

 compression of gases such as air, at constant tempera- 

 tures, is, for once in a popular book, actually assigned to 

 Boyle himself, though even here the pernicious influence 



of the popular quasi-scientific writers has asserted itself in 

 the unwarrantable introduction of the perpetual Mariotte. 

 There are some very sensible remarks on Werner and 

 Hutton, and we are glad to see that William Smith's 

 geological labours are heartily recognised. But what 

 shall we say of passages like the following ? — 



" We owe to him [Scheele] the discovery of chlorine ; 

 and of manganese, barytes, fluor spar, and many other 

 earths whose names I cannot expect you to know," 



Or this— 



" The determination of nitrogen completes the history 

 of the discovery of those gases of which fire, air, and 

 water are composed ; but you will have noticed that we 

 have not yet arrived at the new explanation of chemical 

 changes which was to take the place of ' phlogiston.' 

 The fact is that Black, Bergmann, Cavendish, Scheele, 

 and Priestley, were all so cramped by the old theory, that 

 though they discovered the facts they could not make the 

 right use of them. The man who did this, and who laid 

 the foundation of modern chemistry, was the celebrated 

 French chemist, Lavoisier." 



We have taken the liberty of italicising two words in 

 each of these extracts. 



Again, Fresnel " found that [Dr. Young] also had the 

 same idea [interference], and this led to a number of ex- 

 periments, by which they proved at last that the waves in 

 a natural ray of light do not move tnerely up and down 

 like waves in a pond, but also from side to side ; and that 

 when light is polarised this complex vibration is destroyed 

 and the waves of each separate ray move only in one 

 direction." The italics here are in the text ! 



From the later chapters we make but two extracts ; 

 these will, we fancy, be thought quite sufficient : — 



" If the water were free [in Joule's paddle experiment for 

 the determination of the dynamical equivalent of heat] it 

 would pass on into the air and we should lose sight of it ; 

 but the water is shut in and the force cannot escape, so 

 now it employs itself in dashing to and fro all the little 

 particles which make up the water, and producing the 

 effect we call heat ; and as it produces exactly 1° Fahr. 

 of heat by the time the i lb. weight has fallen 772 feet, we 

 say that yys foot-pounds of force equals i° Fahr. oj heat. 

 You might easily prove to yourself in a somewhat unpleasant 

 way that the force is there ; for if you were to go on 

 turning the paddle violently for many hours, and there 

 were no means for the heat to escape, the motion of the 

 particles would be so violent against the sides of the 

 boiler that it would burst." 



Here again the italics are not ours ; but the whole pas- 

 sage shows clearly that the author has read this part of 

 the subject in works in which scientific terms are used 

 loosely or even inaccurately ; while difficulties have been 

 avoided, not explained. For when "we say that 772 foot- 

 pounds of force equals 1° Fahr. of heat" we commit so 

 many and such astounding blunders that it would be 

 altogether impossible to enumerate them them all in such 

 a notice as this. 



Let us, however, do what we can in a few lines to point 

 out a few of them. Suppose them put as questions by a 

 teacher employing this work as a text-book. 



1. What is a foot-pound of force ? 



To this question the late WiUiam Hopkins, perhaps 

 the ablest instructor whom Cambridge ever produced, 

 would have at once replied, " The old story ; the height 

 of King's College Chapel in acres ! " When will our 

 elementary writers at last recognise that a force may b 



