AUTHOR'S PREFACE TO THE 

 ENGLISH EDITION. 



THIRTY years after the appearance of the first edition of this 

 book, an English translation of it is now being prepared. I 

 regard this as a favourable indication of the permanent value 

 of the book, since it is evident that the standpoint then 

 adopted is intelligible at the present day and is still unsuper- 

 seded. Moreover, it may be concluded that the exposition of 

 the subject is not marred by national prejudices. 



In order to keep pace with the constant progress of the 

 science, two new lectures have been added to the original 

 fourteen. One of these appeared fourteen years ago, upon the j ,f,dT 

 publication of the second German edition of the book ; whilst 

 the other the sixteenth is here published for the first time. 



The English edition is a faithful translation, and, so far as 

 I am able to judge, it is written in a good style. For these 

 features my best thanks are due to the translator. 



I venture to express the hope that the book will find 

 friends amongst the English-speaking peoples, and that it may 

 contribute to stimulate interest in the history of our science. 



A. LADENBURG. 



GRASSENDALE, SOUTHBOURNE-ON-SEA, 

 September 1899. 



