422 



NA TURE 



[September i, 1904 



nanielv, that as British yachts have to cross the 

 Atlantic in order to take part in the cup races, they 

 can nev-er be built with that extreme lightness of hull 

 which is possible in vessels constructed on the American 

 coast. This undoubtedly counts for much. 



Mr. Stephens is an advocate of yachting as a sport, 

 not in the sense of the races for the .\merica or 

 Seawanhaka Cups. He believes in the Corinthian 

 stvie of yachting — owners working their own vessels. 

 It is obvious that if he could have his way mere racing 

 machines would disappear. Some incidents which he 

 describes as to the performances of American yachts, 

 and the special risks run in consequence of the produc- 

 tion of racing machines, are very striking. Only one 

 can be mentioned, that of the Mohawk, a. centre-board 

 schooner 140 feet long and more than 30 feet broad, 

 with a depth of hold of less than 9I feet. This vessel 

 drew only 6 feet when her centre-board was housed. 

 Her sail area was enormous, and she had great initial 

 stability; but in 1876, when at anchor off Staten 

 Island, with all sails set and sheets made fast, she 

 was capsized and sank, carrying with her half a dozen 

 persons. On this side we have had equally e.xtreme 

 dimensions, but under our sailing rules, fortunately, 

 there has not been the same inducement to accept 

 serious risks ; our vessels have not been lacking in 

 stability in the sense that they were liable to be 

 capsized. 



The book mav be heartily commended to all 

 interested in yachting, either as a sport deserving con- 

 tinuance or as a branch of ship design. 



W. H. White. 



A COMPREHENSIVE WORK ON PHYSICS. 



Lehrbuch der Physik. By O. D. Chwolson. Trans- 

 lated into German by H. Pflaum. Second volume. 

 Pp. xxii+1056. (Brunswick: Vieweg und Sohn, 

 1904.) Price 18 marks. 



A SERIOUS problem is presenting itself to lecturers 

 and writers of text-books on physics. Never, 

 perhaps, has there been such rapid accumulation of 

 knowledge, both in respect to phenomena the funda- 

 mental facts of which were found out in the early ages 

 of physical discovery and in respect to new phenomena 

 which reveal themselves in succession to the physical 

 investigator. The brilliant experimental discoveries of 

 Faraday in electrodynamics, the equally distinguished 

 theoretical and experimental researches of Fresnel in 

 optics, the researches of Mayer, Helmholtz, Lord 

 Kelvin, Clausius, and Joule in thermodynamics, which 

 are unsurpassed in importance owing to their wide 

 reaching application to almost every branch of physics, 

 all these make the first half of the nineteenth century 

 unique as an age of physical discovery. This period 

 was followed by one of comparative quiet, in 

 which pM'sicists began to acquire a comfortable feel- 

 ing that the universe was now known ; details un- 

 doubtedly there w-ere to be made out, but no striking 

 discovery was expected. This attitude of content was 

 roughly disturbed by the discovery of Rontgen rays in 

 1895, and still more startlingly so by the discovery of 

 various other types of rays and emanations by 

 Becquerel and his followers. Each of these discoveries 

 NO. I 81 8, VOL. 70] 



has given birth in a most prolific way to a vast crowd 

 of minor discoveries demanding a history of their own ; 

 and meanwhile the accumulation of fact and theory 

 in older subjects has steadily gone on, and the problem 

 which presents itself is, How is this huge and ever 

 increasing amount of knowledge to be successfully 

 presented to a student? It is becoming unmanageable. 

 No single course of lectures can deal adequately with 

 it. College courses are beginning to spread over two 

 years, and even then merely skim the subject. The 

 text-book under review illustrates the state of things. 

 It is the second volume out of four. It extends to 

 more than a thousand pages, and deals onlv with sound 

 and with radiant energy. It contains no elaborate 

 development of mathematical theory — in fact, the weak 

 point of the book is that there is not enough mathe- 

 matics in it. Wherever the mathematics required is 

 other than of simple kind it is omitted ; the final 

 formula may be given, but it is often quoted unproven. 

 How is a student to master the vast mass of material 

 which is extended to him here? It seems inevitable 

 that before long some process of selection must be 

 adopted in order that a student's work mav be made 

 more easy for him. Of course, if a book is intended 

 as a book of reference chiefly, the more encyclopEedic 

 it is the better; but the present volume is intended as 

 a text-book, and not as an. encyclopaedia. We think 

 that the ideal text-book is one which will present such 

 a selection from ascertained knowledge as will give a 

 student an adequate grasp of the facts, principles, 

 and methods of his subject. The selection need not 

 and should not be skimped, but no attempt should be 

 made to include all that is known to be true. 



Regarded as a book of reference, this volume is most 

 admirable, and we commend the enterprise which now 

 brings it into a wider circle of readers. German is 

 not popular amongst English students, but Russian is 

 barred altogether. The matter is excellent and is 

 excellently presented. It is thorough, and is brought 

 well up to date in this edition ; e.g. there is a good 

 account of Siedentopf and Szigmondy's recent work 

 on the vision of (so-called) ultramicroscopic particles. 

 The chapter on interference is specially good. The 

 illustrations throughout are unusually clear, especially 

 those explanatory of the various instruments of observ- 

 ation. 



The man who gets this book has only himself to 

 blame if he learns no physics. Our only quarrel is 

 with the size of the dose. Experience has shown us 

 that a student fights shy of this heroic treatment, and 

 turns for help to the text-books of the cramming 

 institutions. Less formidable treatment might induce 

 him to put the latter away with advantage. 



OUR BOOKSHELF. 



Wilhehn Ostwald. By P. Walden. Pp. vii+120. 



(Leipzig : Wilhelm Engelmann, 1904.) Price 4X. 



net. 

 Prof. Ostwald has only just attained his fiftieth year, 

 and in appearance he is full of life and vigour. He has 

 done and is doing a great work in science ; he is a man 

 one may delight to honour, both for his intellect and 

 for his heart. It may be merely the prejudice of the 

 reticent Englishman, but I must confess to a feeling 

 that these biographies of eminent men in the prime of 



