203 



NATURE 



[February i6, 1922 



naturally placed on the importance of a highly 

 trained fishing population in regard to questions of 

 national defence, and the immediate object of the 

 memorandum was to interest the Government in this 

 and other purely economic questions. In 1919, how- 

 ever, a series of committees met at Fishmongers' 

 Hall under the presidency of Sir Edward Busk, and 

 detailed recommendations dealing with administra- 

 tion, publicity, education, and scientific research 

 were prepared, printed, and circulated. A begin- 

 ning was made with the work of consolidating the 

 statutes relating to fishery. Later on the British 

 Trawlers Federation was formed, and proposals for 

 the creation, by Royal Charter, of a British 

 Fisheries Society were drafted. The author of the 

 book under notice was mainly responsible for 

 all this organisation. Throughout the whole move- 

 ment scientific research was kept in the foreground, 

 and its absolute necessity in any possible scheme of 

 fishery reconstruction was recognised by everyone 

 concerned. It was understood that the industry 

 itself was prepared to back financially a sound pro- 

 gramme of scientific and industrial research, and, 

 without doubt, such programmes of education and 

 research would now have been in practice but for 

 the wholly unexpected partial collapse of the fishing 

 industry that occurred in 1920. 



These remarks will make clear what is the attitude 

 taken up by Mr. Howell in writing his book. It is 

 an account of the life-histories and economic signifi- 

 cance of the various species of marine fishes, and it 

 is very well done indeed. Apart from a few errors, 

 inevitable, perhaps, in a work of this kind, it is a 

 trustworthy account of the material of the marine 

 fisheries, written in a plain but very attractive 

 manner, fortified with clearly constructed statistical 

 statements, very well illustrated and beautifully 

 printed. But, much more than all that, it is a plea, 

 on almost every page, for the further prosecution 

 of marine research in relation to the fisheries, and 

 it aims at the communication of the results of such 

 work to the fisherman and owner of fishing vessels. 

 It is' a useful protest against the pedantry of the 

 fisheries investigator. Little of what has been dis- 

 covered has ever been presented in such a manner 

 as to be understood by the industry in general — 

 though this is quite practicable, as the book itself 

 proves. Men of science almost always write for 

 other men of science, though sooner or later their 

 results must receive application, and this application 

 would come all the more quickly if there were a 

 true liaison between the administrators, the scien- 

 tific workers, and the industry. The furtherance of 

 such a working agreement is, all the way through, 

 the main object of Mr. Howell's admirable book. 



J.J. 



NO. 2729, VOL. 109] 



Wegener's Displacement Theory. 



Die Enstehung der Kontinenie und Ozeane. Von 



Prof. Dr. Alfred Wegener. Die Wissenschaft : 

 Sammlung von Einzeldarstellungen aus den 



Gebieten der N aiurwissenschaft und der Technik. 



Herausgegeben von Prof. Dr. Eilhard Wiede- 

 mann. Band 66. Zweite ganzlich umgearbeitete 



Auflage. Pp. viii-l-135. (Braunschweig: 



Friedr. Vieweg und Sohn, 1920.) 30 marks. 



THIS book makes an immediate appeal to 

 physicists, but is meeting with strong opposi- 

 tion from a good many geologists. This opposition 

 is to be expected, for the author replaces the whole 

 theory of sunken continents, land bridges, and great 

 changes of earth temperature by a displacement 

 theory. 



Prof. Wegener's thesis is that the continents are 

 of lighter material, and float like icebergs on a 

 heavier plastic which reaches its highest level at the 

 bottom of the oceans ; the poles are not fixed relative 

 to the plastic, and have occupied widely different 

 positions, as, for instance, when Central Europe was 

 a Sahara, or, again, when the great coal fields were 

 laid down along a great circle (equator); land 

 masses under gravitational influence move away from 

 the poles and westwards. 



Thus the Americas in their westward drift have 

 heaped up the Andes and the Rockies. The South 

 Atlantic opened early, but the northern portion did 

 not exist until much more recent times. At the 

 great Ice age, in fact, the glaciation in both hemi- 

 spheres was due to an ordinary polar ice cap. 

 India once stretched down over the Indian Ocean, 

 being united to Africa and Australia. Since that 

 time the Himalayas have been piled up, and Aus- 

 tralia has left New Zealand far behind. 



Actual measurements of continental and sea levels 

 establish the fact that instead of there being a 

 random distribution about one level there are two 

 well-marked averages, a fact difficult to explain on 

 any subsidence theory. Again, it was shown by 

 Wilde that the earth's magnetic field can be closely 

 imitated on a globe where iron sheets are placed 

 over the ocean areas. ' On the present theory this is 

 due to the plastic interior being richer in iron and 

 rising higher under the oceans, where there is thus 

 a thicker layer below the temperature at which iron 

 loses its magnetic properties. Recent astronomical 

 work has shown that the latitude of North American 

 and European stations is increasing, but in the 

 absence of measurements from the Far East we 

 cannot prove that this is not due to a displacement 

 of the pole. 



The book brings forward a mass of geological 



