rHEFACE 



The contents of the present volume, with three 

 exceptions, are either popular lectures, or addresses 

 delivered to scientific bodies with which I have 

 been officially connected. I am not sure which 

 gave me the more trouble. For I have not been 

 one of those fortunate persons who are able to 

 regard a popular lecture as a mere hers dCceuvre, 

 unworthy of being ranked among the serious efforts 

 of a philosopher; and who keep their fame as 

 scientific hierophants unsullied by attempts — at 

 least of the successful sort — to be understanded 

 of the people. 



On tlie contrary, I found that the task of 

 putting the truths learned in the field, the 

 laboratory and the museum, into language which, 

 without bating a jot of scientific accuracy shall be 

 generally intelligible, taxed such scientific and 

 literary faculty as I possessed to the uttermost; 

 indeed my experience has furnished me with no 

 better corrective of the tendency to scholastic 

 pedantry Avhich besots all those who are absorbed 



