SECOND EDITION. ix 



in each Epoch are not properly chosen. I have 

 had, therefore, little to alter, either in the general 

 outline or in the detail of the work. 



The German translator of this History, the late 

 Director of the Imperial Observatory at Vienna, 

 M. Littrow, has added to his translation, besides 

 other valuable notes, a biographical notice of each 

 of the persons mentioned in the work. But though 

 these additions are very interesting, they did not 

 belong to the plan of the work as I had conceived 

 it, and would have greatly augmented its bulk. I 

 have, therefore, with a few exceptions, omitted them. 



I have not introduced any new branches of 

 science into this edition, and on this account, among 

 others, I have said nothing of the recent progress 

 of Organic Chemistry. The discoveries which are 

 alleged to have been made in that department will 

 require to have many intermediate steps clearly 

 marked and fairly established, before they can stand 

 by the side of Historical Chemistry as examples of 

 Inductive Science. Still less have I attempted to 

 introduce any notice of recent steps in the sciences 

 which I have more especially termed Organic, as 

 Zoology and Physiology. I am aware that the study 

 of the nervous system, for instance, has been prose- 

 cuted with highly interesting results. But I never 



