June 15, 1905] 



NA TURE 



149 



sciences in the age in wliieh he live«i. What is 

 accomplished in one generation is the Imindalion for 

 the aehievenients of the next. 



Thai the subject is not cxhaiislcd wo may easily 

 see \)\ remarking Ihi' progress ihal has been made in 

 one of its departments most I'asilv reviewed, since 

 Prof. Korel finished tliat part of his worl':. In biology, 

 even in the sitnple cataloguing of the lacustrine 

 animals and plants, it is obvious (hat the work accom- 

 plished iiiidir his guidance is no more than a be- 

 ginning in this direction, .ind spieialists in any branch 

 find abundance still to do. Il is with no intention of 

 belittling the work of Prof, l-'orrl that this aspect of 

 the subject is adverted t<i. It is a great work 

 patiently carried through, and will serve as a found- 

 ation for all future limnological studies. 



IIENR Y Sine WICK '.s KSSA VS. 

 Miscellaneous Essays ami Aiiiircsscs. By Ilenr\ 



Sidgwick. Pp. vii + .<7i. (London: Macmillan 



and Co., Ltd., 1904.) Price lo.s. net. 

 T N this volume we have the first instalment of the 

 ^ shorter essays of that brilliant thinker, Henry 

 Sidgwick. They have been chiefly collected from 

 journals and reviews, but two are now published for 

 the first time. His philosophical lectures and papers 

 are reserved for a companion volume. In a way, the 

 selection of articles now before us illustrates a period 

 of thirty-si.\ years of the life of one of the most 

 striking personalities of our time, ;ind on that account, 

 and from their breadth of view, they liavi' a value even 

 though the occasion of their appearance is long past. 



Of the sixteen papers, si.\ are literary or critical, 

 six deal with questions of socialism and economics, 

 and four with education and university affairs. We 

 were surprised and somewhat disappointed to find no 

 rrminiscence of his activity in connection witli the 

 education of Englishwomen, but perhaps more may 

 III- expected when the histories of Newnham and 

 (iirlon come to be writlin. 



.\ detailed review of the essays on Shakes])eare, 

 .Matthew .Arnold, and ("lough, or of those on political 

 iconomy or sociology, h.ardly falls within the sphere of 

 this joLuaial, but few of our I'eadi-rs who .are interested 

 in the burning question of the best education for men 

 of science will regret having read Sidgwick's essay 

 on "The 'J'heory of Classical Education," reprinted 

 from I'". W. Farrar's " Essays on a Liberal Educa- 

 tion," which was originally published in 1867. In the 

 light of the recent controversy on the (jreck question 

 nuicli of this excellent paper reads as if it had been 

 written vestcrday, and it is difficult to avoid the 

 rellection that if several of the writers of contro- 

 versial letters to the Times had read this essay of forty 

 \(ars ago, both their matter and manner might have 

 been improved. 



With respect to the classical element in a scientific 

 education, .Sidgwick was of opinion th.at although 

 science had at length broken its connection with what 

 was so long the learned language of Ii^urope, yet 

 everyone who aspires to become a " learned " man of 

 science will require to read Latin with ease, but that 

 NO. 1859, VOL. 72] 



the sole stock-in-trade of Greek necessary for hi 111 

 would be a list of words that he could learn in a d.av 

 and the use of ;i dictionary that he might acquire in 

 a week. In other words, he .appeared to be in favour 

 of the retenlion for the highest class of science 

 students of th.at modicum of Cjreek which is at present 

 compulsory at Oxford and Cambridge, only he would 

 perhaps have liked to see it reduced and treated as a 

 distinct part of the direct teaching of English. 



.\ clear distinction is drawn between natural .ind 

 artificial educations, and between the effects of literary 

 and of scientific training. With regard to the latter 

 Cuvicr's famous remark is quoted with approbation : — 



" Every discussion which supposes a classification of 

 facts ... is performed after the same manner ; and 

 he who h.'is cultivated this science merely for amuse- 

 ment, is surprised at the facilities it affords for dis- 

 ent.angling all kinds of affairs." 



lie admits that a student of languages could not 

 honestly claim an analogous advantage for liis own 

 pursuit. The editors are justified in the inclusion of 

 the ess.ay on " Idle Fellowships " in spile of the f.act 

 that the evils of which it compl.ains have greatly 

 diminished. The general educational considerations 

 discussed are of so wide a bearing that they are not 

 less true now than in 1S76, when the essay was 

 published. 



We feel certain that those who peruse this volume 

 will share our gratitude to the editors for their share 

 in the re-publication. 



OUR BOOK SHELF. 



Ihr l„si,lali,n, of Electric Macliiiirs. Hv 11. W. 



I'urner :md II. M. Hobart. Pp. ■xvi + ji,7. 



(London ; Whillaker ,iiul Co., ii|o:;.) Price lo.s. fx/. 



net. 

 Tni; perfecting of the modern dyn.amo electric machine, 

 and the necessity of high potential differences have 

 within recent years quite altered our ideas about 

 insulation. Electrical engineers have come to view 

 the subject from a different standjioint on account 

 of the importance of disruptive strength of the material 

 a|)art from conduction pure and simple. The book 

 under review appears at a very appropriate time. 

 Our knowledge of the physical properties of insula- 

 tors is now sufficient, and the want of a really good 

 book on the subject is great enough to justify its 

 a])pearance. It will be welcomed by the elecirical 

 engineer as a most valuable addition to his library. 



The book opens with an account of the reqiiisiles 

 for insulating materials, and the most perplexing 

 phenomena met with during- the testing of the same. 

 Why is it that air has comparatively such low di- 

 electric strength, and yet it is a verv good insulator 

 as ordinarily understood? .\gain, why does the 

 apparent dielectric strength per unit thickness of such 

 a substance as mica vary with the thickness? These 

 and many other matters difficult to understand are 

 laid before the reader. The properties of insul.ating 

 materials and the influences of temperature and 

 moisture upon them are next dealt with. The 

 .authors quite rightly lay stress upon the testing of 

 insulators at, or even exceeding, their working limits 

 of temperature, ,and the futility of baking to obtain 

 lempor.ary insulation unless moisture be permanently 

 excluded. When dealing with the influence of brush 

 discharge mention might with advantage have been 

 made of the production of nitric acid, and the ultimate 



