a 



/?<?5 

 TEANSLATOE'S PBEFACE 



TO NEW EDITION. 



IN 1891 the seventieth birthday of Hermann von Helm- 

 holtz, and the forty-ninth anniversary of his taking the 

 degree of Doctor of Medicine, was celebrated in Berlin in 

 a manner which, whether for its universality or import- 

 ance, has, perhaps, never fallen to the lot of a Man of 

 Science during his lifetime. 



The demand for a new edition of the translation of 

 the two volumes of Von Helmholtz's Popular Scientific 

 Lectures suggests that this is an appropriate occasion for 

 a re-issue under conditions which make them accessible 

 to a larger circle of readers. 



The present edition is identical with the preceding 

 ones ; discussing as they do, with the hand of a master, 

 fundamental scientific problems, these Lectures are not 

 likely to be soon out of date. 



To the second volume has been added a remarkable 

 autobiographical account of the Author's scientific career 

 and development, which formed the subject of an address 

 given by Von Helmholtz in reply to the addresses of 

 congratulation on the occasion of his Jubilee. This is 

 taken, by kind permission of the publisher, M. Hirschwald, 

 from a collection of the addresses and speeches delivered 

 on that occasion. 



E. ATKINSON. 



March 1893. 



425182 



