CORRESPONDENCE 



MACH'S MECHANICS 



To the Editor of " Science Progress " 



Sir, — I am very much obliged for the kind things " C." has 

 said of my edition of the Supplement to Mach's Mechanics on 

 p. 679 of the current number of Science Progress, but I beg 

 to be allowed to make a short reply to his remarks on the plan 

 adopted of publishing the supplement separately from the 

 Mechanics. This plan was my own suggestion, and I recom- 

 mended it to the publishers simply because, if a new edition of 

 the Mechanics were made, the student would have had to buy 

 yet another expensive book if he wished to know the rather 

 extensive alterations made by Mach in the last edition issued 

 before his death. With regard to the careful preservation of 

 what Mach wrote and the indication of when he wrote it, which 

 are given in the English but not the German editions, I of 

 course agree with " C." that this is of no importance and even 

 harmful to a student : it is, however, useful to many who are 

 concerned with the development of science to know how time 

 and new tendencies affected Mach's thought. 



Under the present system a comparatively small outlay will 

 permit those who already possess the 1907 English edition to 

 bring the whole up to date. The saving of about 55. 6d. may 

 be a consideration at the present time. 



I am, Sir, your obedient servant, 



Philip E. B. Jourdain. 



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