394 



NA TURE 



{Sept. 9, 1875 



their own waters. But no one ever saw an Irish fishing- 

 boat in either a Scotch or English sea. The Englishmen 

 and Scotchmen, with their capital continuously employed 

 throughout the year, beat, of course, the Irishman who 

 leaves it idle and unemployed for three-fourths of it. 



The view which we have thus expressed is not, how- 

 ever, shared either by the friends of Ireland or the Irish 

 Inspectors. In their eyes the decrease in the number of 

 Irish fishermen is equivalent to the decay of the Irish 

 fisheries ; and both of these are due to the unsympathetic 

 attitude of this country. Last year nothing would do any 

 good but loans. Now that the Reproductive Loan Fund 

 has been utilised for this purpose with effects which we 

 shall immediately notice, nothing will do any good but a 

 safe and commodious harbour at Arklow. Such a har- 

 bour "is most necessary for the successful prosecution of 

 both herring and oyster fisheries," and " unless something 

 be done, there is little hope of any substantial improve- 

 ment." We have no desire to discourage the construction 

 of safe and commodious harbours, but we should like to 

 ask the Irish Inspectors whether they ever heard of a 

 place in England called Yarmouth. It is as important a 

 fishing station as Arklow, it is on as stormy a shore ; but 

 when a storm is raging, the Yarmouth fishermen have to 

 stand out to sea to avoid being'driven on to the coast. We 

 never heard that the want of a harbour at Yarmouth had 

 destroyed the Yarmouth fishery ; and we think that Yar- 

 mouth has at least as good a claim as Arklow for the con- 

 struction of such a harbour. The new system of loans to 

 fishermen remains for consideration. There has, of, course, 

 been no want of applicants for the loans. 2,800 indi- 

 viduals have already applied for the money, and we have 

 no doubt there are a good many more quite prepared to 

 follow their example. 1,300 of the 2,800 applications 

 emanate from County Galway, and 160 of these applicants 

 five in one parish. No more than six of the 160 "fulfil 

 the conditions which should entitle them to obtain a 

 loan ! " We presume that as the Inspectors pointedly refer 

 to the 160 applicants, they may be regarded as fair 

 examples of the 2,800 who have applied. In that case 

 only 105 persons throughout Ireland will, in the lenient 

 judgment of the promoters of the policy, be entitled to 

 participate in the loan. Is it possible to conceive a more 

 striking illustration of the consequences of the policy ? 



MAGNUS'S ''ELEMENTARY MECHANICS" 

 Lessons in Elemeiitary Mechanics introductory to the 

 Study of Physical Scietice, with manerotts Exercises. 

 By Philip Magnus, B.Sc, B.A. (Longmans, 1875.) 



IN order to assign any work to its proper place it is 

 necessary that we should try to ascertain what is the 

 author's aim in writing it, and also to see if that aim be 

 to any fair extent attained ; further, we should take into 

 our account the consideration of the question whether if 

 the author's end be attained it is one worth arriving at. 

 If the verdict on all these issues be favourable, then we 

 may say that the raisoti d'etre of the work is justified. 

 For the aim of the present volume the title will suggest 

 at once that the author does not attempt to produce a 

 treatise which shall enter into comparison with such 

 works as those produced by Thomson and Tait. Let us 

 hear his own statement : " The lessons are intended for 



the use of those who have had no previous acquaintance 

 with the subject ;" and so he has endeavoured to bring into 

 prominence the leading principles of Mechanics, and to 

 exemplify them by simple illustrations. Here we may 

 observe that the term mechanics is used in the ordinary 

 acceptation of that word now-a-days, i.e., as the science 

 of the motion and equilibrium of bodies, and not in the 

 Newtonian sense to which Messrs. Thomson and Tait 

 seek again to restrict it. Starting on the hypothesis that 

 the idea of Motion is more elementary than that of Force, 

 since it is only from a combination of forces that equi- 

 librium can result, the author makes the subject of Statics 

 depend upon the laws of Dynamics. Hence the propo- 

 sition, which is generally cited as that of the Paral- 

 lelogram of Forces, Mr. Magnus derives at once from 

 Newton's second Law. 



After a short preliminary introduction we have " Kine- 

 matics—Motion " treated under the heads of Measure- 

 ment of Motion and Falling Bodies ; then " Dynamics — 

 Force," under which heading we have Measurement of 

 Force, the Laws of Motion, Energy, Machines. 



The second part of the book discusses " Statics — Rest," 

 under the following heads ; Theory of Equilibrium, 

 Centre of Gravity. 



The style is lucid, the solved exercises carefully chosen, 

 the work compact. With the exception above mentioned, 

 of Statics being made dependent on Dynamics, the 

 arrangement and matter are much the same as we find in 

 English treatises. An intelligent boy ought in a few 

 months to be able to make himself master of the greater 

 portion of this small book, which Mr. Magnus has aimed 

 at making suftrciently elementary to be placed in the 

 hands of a beginner. What we consider to be higher 

 praise is that we believe it to contain nothing that the 

 student will have to unlearn in a subsequent portion of 

 his career. We can recommend it as a trustworthy in- 

 troduction to more advanced text-books. 



We have endeavoured to test its accuracy as regards 

 the answers to the numerous questions scattered over its 

 pagf s. Of these there are 279 in the Dynamical portion, 

 192 in the Statical portion, besides 79 questions in an 

 appendix composed of papers from the Matriculation, 

 South Kensington, College of Preceptors, Oxford Local, 

 Cambridge Local, and other Examinations. These answers 

 seem to us to be exceptionally correct, as, though we have 

 tried them all, we differ from Mr. Magnus's results in only 

 a dozen cases ; some of these cases are apparently clerical 

 errors. We make this statement, taking into account two 

 or three slips of errata which have been subsequently dis- 

 tributed by the author. 



In Ex. 23, p. 86, i-368th should be i-368th, i.e., 3J3 ; 

 § 199, we think, would not be easy for the pupil unless he 

 had some aid from a tutor. Some of the questions given 

 to the Matriculation candidates of the University of 

 London seem to us hardly suitable for them ; we shall 

 select one, because even so experienced a teacher as the 

 writer of the work we have noticed at first fell into an 

 error. The question is : " Suppose that at the equator 

 a straight, hollow tube were thrust vertically down towards 

 the centre of the earth, and that a heavy body were 

 dropped through the centre of such a tube. It would 

 soon strike one side ; find which, giving a reason for your 

 reply." The author gives an answer which we have heard 



