PREFACE. 1\ 



tific knowledge than is possessed by every man of 

 education : — in language intelligible to such a 

 reader, he endeavours to explain the great pheno- 

 mena of nature. 



How far the Author has succeeded in the task 

 he proposed to liimself, I must leave to the 

 decision of the reader ; but I may be allowed to 

 state that I was induced to undertake an English 

 edition of these Letters — the contents of which 

 are not immediately connected with my special 

 pursuits — by no other motive than the desire of 

 rendering accessible to the Public a source of 

 information from which I had myself derived no 

 less of profit than of pleasure. 



In conclusion, I have to express my sincere 

 thanks to my friend, Mr. C. B. Mansfield, for his 

 valuable assistance in editing the present volume. 



A. W. H. 



London, 

 October 26, 1851. 



■Mi 



