INTRODUCTION. 



ris my purpose to write the History of some of the most im- 

 portant of the Physical Sciences, from the earliest to the most 

 recent periods. I shall thus have to trace some of the most remark- 

 able branches of human knowledge, from their first germ to their 

 growth into a vast and varied assemblage of undisputed truths ; from 

 the acute, but fruitless, essays of the early Greek Philosophy, to the 

 comprehensive systems, and demonstrated generalizations, which com- 

 pose such sciences as the Mechanics, Astronomy, and Chemistry, of 

 modern times. 



The completeness of historical view which belongs to such a de- 

 sign, consists, not in accumulating all the details of the cultivation of 

 each science, but in marking the larger features of its formation. The 

 historian must endeavor to point out how each of the important ad- 

 vances was made, by which the sciences have reached their present 

 position ; and when and by whom each of the valuable truths was 

 obtained, of which the aggregate now constitutes a costly treasure. 



Such a task, if fitly executed, must have a well-founded interest for 

 all those who look at the existing condition of human knowledge with 

 complacency and admiration. The present generation finds itself the 

 heir of a vast patrimony of science ; and it must needs concern us to 

 know the steps by which these possessions were acquired, and the 

 documents by which they are secured to us and our heirs forever. 

 Our species, from the time of its creation, has been travelling onwards 

 in pursuit of truth ; and now that we have reached a lofty and com- 

 manding position, with the broad light of day around us, it must be 

 grateful to look back on the line of our vast progress ; to review the 

 journey, begun in early twilight amid primeval wilds ; for a long time 

 continued with slow advance and obscure prospects ; and gradually 

 and in later days followed along more open and lightsome paths, in a 

 wide and fertile region. The historian of science, from early periods 

 to the present times, may hope for favor on the score of the mere 

 subject of his narrative, and in virtue of the curiosity which the men 



