vi PREFACE TO THE 



point of view, and thus, to write a new work, not 

 to publish a new edition. 



I have, however, in Notes at the end of each 

 Book, given an account of some of the most impor- 

 tant recent advances in each subject, considered as 

 an Inductive Science. I introduce this limitation, 

 because it is my justification, as well in the present 

 as in the former edition, for the omission of many 

 topics which are of great interest, both in a prac- 

 tical and in a scientific view, but which are applica- 

 tions of discoveries already made, not steps towards 

 discovery ; deductive results of laws of nature, not 

 inductions of such laws from observation. This was 

 my reason for passing over such inventions as 

 printing and porcelain, glass and gunpowder, steam- 

 boats and rail -roads, gas -lighting and chemical 

 bleaching, in the former edition ; this is my excuse 

 for saying nothing now of photography, the electric 

 telegraph, and other striking recent inventions. I 

 have omitted, for like reasons, many remarkable 

 inventions, still more directly bearing upon the 

 progress of science, as Daniel's galvanic battery, 

 and the very ingenious battery of Mr. Grove. Even 

 implements of scientific research, if we are not able 

 to bring into view the points to which they lead, 

 cannot be put in their place in the history of 



