Xvi INTRODUCTION. 



Helmholtz and Clausius, or fail to see the probable in- 

 flueuce of their writiDgs on the science of the coming 

 time. For many years, therefore, it was my habit to 

 place every physical paper published by these eminent 

 men within the reach of purely English readers. 



The translation of the lecture on the ' ^Yechselwirkung 

 der Naturkrafte,' printed in the following series, had this 

 ori<nn. It appears here with the latest emendations of 

 the author introduced by Dr. Atkinson. 



The evident aim of these Lectures is to give to those 

 ' whose education has been mainly literary,' an intelligent 

 interest in the researches of science. Even among such 

 persons the reputation of Helmholtz is so great as to 

 render it almost superfluous for me to say that the intel- 

 lectual nutriment here offered is of the very first quality. 



Soon after the publication of the ' Tonempfindungen ' 

 bv Helmholtz, I endeavoured to interest the Messrs. Long- 

 man in the work, urging that the publication of a trans- 

 lation of it would be an honour to their house. They 

 went carefully into the question of expense, took sage 

 counsel regarding the probable sale, and came reluctantly 

 to the conclusion that it would not be remunerative.^ 

 I then recommended the translation of these ' Populare 

 Vortrage,' and to this the eminent publishers immediately 

 agreed. 



Hence the present volume, brought out under the 

 editorship of Dr. Atkinson of the Staff College, Sandhurst. 

 The names of the translators are, I think, a guarantee 

 that their work will be wortliy of their original. 



JOHN TYNDALL. 



Royal Institution: 



MarLh 1873. 



' Since the date of the foregoing letter frim Professor Tyiidall, Messrs. 

 Longman & Co. have made arrangements for the translation of Helmholtz's 

 Tonempfindungen, by Mr. Alexander J. Ellis, F.R.S., &c. 



