Xiv INTRODUCTION. 



started with the axiom that matter is indestructible, all disappear- 

 ance of material during his operations was chargeable to their im- 

 perfection. He was therefore compelled to improve them to ac- 

 count in his result for every thousandth of a grain with which he 

 commenced ; and as a consequence of this inexorable condition, 

 analytical chemistry advanced to a high perfection, and its conse- 

 quences to the world are incalculable. Precisely so with the anal- 

 ysis of forces. So long as they are considered capable of being 

 created and destroyed, the quest for them will be careless and the 

 results valueless. But the moment they are determined to bo in- 

 destructible, the investigator becomes bound to account for them ; 

 all problems of power are at once affected, and the science of dy- 

 namics enters upon a new era. 



The views here briefly stated will be found fully and variously 

 elucidated in the essays of the present volume ; in these introduc- 

 tory remarks I propose to offer some observations on their history 

 and the extended scope of their application. 



I have spoken of the principles of Correlation and Conservation 

 of Forces as established ; it may be well to state the sense in which 

 this is to be taken. They have been accepted by the kading scien- 

 tific minds of all nations with remarkable unanimity; their discus- 

 sion forms a leading element in scientific literature, while they oc- 

 cupy the thoughts and guide the investigations of the most philo- 

 sophical inquirers. But while science holds securely her new pos- 

 session as a fundamental principle, its various phases are by no 

 means completely worked out. Not only has there been too little 

 time for this, even if the views were far less important, but the 

 questions started lie at the foundation of all branches of science, 

 and can only be fully elucidated as these advance in their develop- 

 ment. The new doctrine of forces is now in much the same con- 

 dition as was the new astronomy of Copernicus. It is not with- 

 out its difficulties, which time alone must be trusted to remove ; 

 but it simplifies so many problems, clears up so many obscurities, 



