474 SCIENCE PROGRESS 



in future to publish as early as possible at least an abridged summary of 

 the results. 



The magnetic observations secured on this expedition comprised daily 

 magnetographs of three components of the earth's magnetic field, supple- 

 mented by absolute observations at more or less regular intervals for the 

 purpose of determining the base-line values of the magnetographs. A 

 large amount of material was therefore available for discussion. In addition, 

 by previous arrangement, a number of simultaneous quick runs were obtained 

 in the Antarctic and at various permanent observations, during which were 

 recorded, on a very open-time scale, the variations in the several components 

 of the earth's magnetic field. 



From a discussion of the absolute observations, the most probable base- 

 line values are deduced, and the hourly values of the elements hence obtained 

 from the magnetographs. These enable the diurnal inequalities and the 

 daily absolute ranges to be determined and discussed. The results obtained 

 are compared with those obtained during the National Antarctic Expedition 

 of 1902-4 and with those obtained at Observatories in lower latitudes. 

 This is followed by a discussion of the annual and diurnal variation of 

 magnetic character and of the evidence in favour of a 27-day period. A 

 detailed comparison of the records obtained during certain of the quick 

 runs in the Antarctic and at other observatories is also given. The Antarctic 

 is a region of numerous and violent magnetic storms, and most of the re- 

 mainder of the discussion is occupied with a description of the various 

 types of disturbance and with comparison of the records of the more promi- 

 nent storms obtained in the Antarctic and elsewhere. A chapter is included 

 dealing with the connection between magnetic disturbances and aurora. 



Although no very important new conclusions are arrived at, and the 

 discussion is in general confirmatory of previous knowledge, it forms 

 material addition to the data on which any theory of the variations of the 

 terrestrial magnetic elements in general, and of magnetic storms in particular, 

 must be based. The hourly values of the elements have been tabulated at 

 the end of the volume, so that the material is available for any other investi- 

 gator to discuss at any future time any points which may not have been 

 touched upon in the present volume. 



H. S. J. 



Traite de Dynamique. By Jean D'Alembert. Les maitres de la pensee 

 SCientifique. Collection de memoires et ouvrages. Publiee par les 

 soins de Maurice Solovine. [Two volumes. Pp. xl -f- 102, 182.] 

 (Paris; Gauthier Villars, 1921. Price 7 francs.) 



Perhaps in no other great branch of human knowledge have the professors 

 in the past paid so little regard to the history of their subject as in mathe- 

 matics and its allied sciences. To many students of mechanics the names of 

 Archimedes, Galileo, Newton, D'Alembert and Lagrange are but convenient 

 labels for certain laws and theorems, and their knowledge of these men is con- 

 fined to a few pleasing anecdotes of doubtful authenticity. Happily, signs are 

 not wanting of a change for the better and there is at the present time a 

 marked revival of interest in the history of mechanics. This is partly due to 

 the influence of modern theories which have driven us to a deeper study of the 

 work of the old masters. An Einstein was needed to show us how little we 

 had understood of the genius of Newton. But we must also acknowledge our 

 debt to the educationalists who have shown us that the best we can do for our 

 students is to bring them into a living contact with the greatest minds that the 

 race has produced. If in their turn they are to advance and extend the bounds 

 of knowledge it is not suf&cient that they should be our disciples : we must 

 lead them into discipleship with those greater men who have made our work 



