Dec. 3, 1885] 



NA TURE 



99 



Numerical Exercises in Cheinisiry. By T. Hands, M.A,, 



F.R.A.S. (London: Sampson Low and Co., 18S4.) 

 This is a neat little book of easy arithmetical exercises 

 on chemical problems which are likely to crop up in the 

 course of laboratory work. The examples, about 650 in 

 number, are to some extent original and partly collected 

 from examination papers. Tliey extend over a good deal 

 of the physical ground more intimately connected with 

 chemistry, and appear to be generally of a useful charac- 

 ter. There is no attempt at theoretical instruction beyond 

 what is absolutely necessary for setting out a question. 

 The first four pages are given to exercises on the metric 

 system, after which thermometers, heat, chemical equa- 

 tions, &c., are dealt with. The book will be very useful 

 for students who have got a little way into the subject, 

 but still in the position of beginners. 



An Introduction to the Differential and Intei;ral Calculus, 

 with Examples of Application to Mecha?iical Problems. 

 By W. J. Millar, C.E. (London: Blackie and Son., 

 18S5.) _,__^__.__ ^ 



This is the second attempt within a very short time to 

 give an elementary and, as far as possible, interesting 

 exposition of the principles of the Differential and 

 Integral Calculus. One cannot but feel sympathy with 

 the authors of such attempts, for, sooth to say, we often 

 find writers on the less elementary branches of mathe- 

 matics anything but good teachers or editors of students' 

 text-books. 



The present little work has the peculiarity that, being 

 written for engineering students, its illustrations are 

 mainly such as can best be appreciated by those who 

 have an acquaintance with applied dynamics. It is 

 clearly written, the examples are well chosen, and it is 

 on , the whole wonderfully accurate, considering the 

 appearance usually made by practical men when dealing 

 with pure mathematics. On page 7 no distinction is 

 made between the increment of x and the square of the 

 increment oi x ; on page 12 there is a faulty investigation 

 of the rule for the differentiation of a quotient ; and one 

 or two others might be specified. These do not detract 

 much, however, from the value of the exposition as a 

 whole, and we cordially hope that the little book may 

 attain its object of smoothing and rendering attractive to 

 practical engineers the rather forbidding pathway leading 

 to the higher mathematics. 



LETTERS TO THE EDITOR 

 [ Tke Editor does not hold himself responsible for opinions expressed 

 by hiscorrespondeuts. Neither cati he undertake to icturn, 

 or to correspond loith the writers of, rejected manuscripts. 

 No notice is taken of anonymous communications. 

 [ The Editor urgently requests correspondents to keep their letters 

 as short as possible. The pressure on his space is so great 

 that it is impossible otherwise to insttre the appearance even 

 of comjnunications containinginteristing and novel facts.^ 



The Whole Duty of a Chemist 

 I CANNOT complain if the addres.s which I delivered a few 

 weeks ago to the Institute of Chemistry, although it received an 

 extent of encomium for which I was :quite unprepared, should 

 meet here and there with adverse, not to say unfriendly, criti- 

 cism. Naturally enough, the inculcation of sturdy self reliance 

 is displeasing to the new apostolate of sponging upon othei-s, 

 though it scarcely, I think, justifies a resort to the dialectic 

 juggle of representing the defence of one side of a chemist's 

 duty as meant to be a deliberate expression of " the whole duty 

 of a chemist." The Chemical Society takes cognisance of 

 chemists in one aspect of their work, the Institute of Chemistry ■ 

 takes cognisance of the same individuals in another aspect ; and 

 one really need not be a conjuror, though it may put some strain 

 on the fair-mindedness of an editor, to perceive that an address 

 intended for the one organisation would be unsuitable for the 



other. That distinguished man, the late Dr. James Young, F. R. S. , 

 whom you so complacently sneer at, was not a professional 

 chemist at all, but a manufacturing chemist. He was 

 a first-rate manufacturer, whereas Reichenbach was 

 but a third-rate or fourth-rate investigator, if so much ; 

 and, your opinion notwithstanding, it is commonly held 

 that the first-rateness of the one man in his own walk 

 more than counterbalanced whntever weight attached to the 

 higher walk of the other. I may cite for your information 

 Sir Frederick Abel, Dr. Frankland, Prof. Dewar, and the 

 'ate Dr. Stenhouse, as being eminent professional chemists. 

 Though of high repute in forensic circles, I am not aware of 

 their being never heard of at the learned Socie'ies ; but I am 

 aware that, in common with other leading chemists of the 

 country, they have had the bad taste to be contemptuous of your 

 own contributions to chemical science. Can it really be that 

 this circumstance has affected unconsciously the spirit of your 

 leading article ? I would suggest , moreover, for your editorial 

 consideration, that to supplement criticism of an author's per- 

 formance with flippant insinuations as to his personal conduct" 

 and career, is hardly in accordance with the best traditions of 

 scientific journalism ; while it constitutes undeniably bad art, 

 as implying that the production criticised did not of itself afford 

 adequate opportunity for attack, even, of course, with an editor's 

 happy privilege of misrepresentation. As regards the reflections 

 so unmistakably made on myself personally, I have little 

 fear that the irreproachable tone of your remarks will 

 serve to suggest the measure of their trustworthiness ; 

 and will only observe " happy are they that hear their 

 detractions, and can put them to mending." As regards, how. 

 ever, your disparagement of the chemical profession at large, 

 from which, I trust, it may not suffer beyond hope of recovery, 

 I would venture to remind you that even that other profession, 

 of which you are so magnanimous a member, has had its calum- 

 niators ; and the words of a well-known satirist of the last 

 century are considered by some to be as applicable now as ever, 

 that " Of all the cants which are canted in this canting world, 

 the cant of criticism is the most tormenting." Sterne was, 

 happily, unacquainted with the cant of scientific mendicancy, or 

 he might have added that that also was a very fine cant in 

 its way- William Udling 



Oxford, December I. 



[We print the above without 'comment except on the two fol- 

 lowing points. Dr. Odling has entirely misunderstood the allusion 

 to the late Dr. Young : no sneer was intended, as will be obvious 

 on a perusal of the whole paragraph. He has also taken as per- 

 sonal to himself remarks made on types not individuals. — Ed.] 



A Stray Balloon 



The Times ])uljlished on September 29 a short extract from 

 the Bciiniida Royal Gazette, communicated by me, describing 

 Ihe appearance of a balloon, passing over Bermuda on August 

 27, and which I suggested might be one of those which ascended 

 this year in England or France, and had not been subsequently 

 heard of. This was followed by a letter from Mr. Charles 

 Harding, F.R.IVIet.Soc. , commenting on the "extreme im- 

 probability" of a balloon crossing the Atlantic, and even adding 

 that " a little practical experience in ballooning suggests it to be 

 thoroughly impossible." 



As the columns of the Times are hardly suitable for the dis- 

 cussion, may I ask that you will allow me to make public 

 through Nature Ihe further information I have received on the 

 subject. 



First, the impossibility is, I think, disposed of by the fact that 

 one of the balloons sent up from Paris during the siege did 

 actually travel rather more than half the distance, having 

 descended in Iceland, where it was found long after. We know 

 not how long either balloon was on its course, but it would be 

 bold to assert that if one balloon can float four or five days 

 another cannot float ten days. We know nothing of the excep- 

 tional conditions which prolonged the buoyancy : an unusually 

 good varnish, peculiar folding of the silk in its collapse, a film 



