INTRODUCTION, 



since Newton failed to give currency to the new views. But the 

 salient and impregnable demonstration of Rumford, and the ingen* 

 ious experiments of Davy, facts which could neither be evaded nor 

 harmonized with the prevailing errors, were not without influence. 

 That there was a general, though unconscious tendency toward a 

 new philosophy of forces, in the early inquiries of the present cen- 

 tury, is shown by the fact that various scientific men of different 

 nations, and with no knowledge of each other's labors, gave ex- 

 pression to the same views at about the same time. Grove and 

 Joule of England, Mayer of Germany, and Colding of Denmark, 

 announced the general doctrine of the mutual relations of the forces, 

 with more or less explication, about 1842, and Seguin of France, 

 it is claimed, a little earlier. From this time the subject was closely 

 pursued, and the names of Helmholtz, Holtzman, Clausius,* Faraday, 

 Thompson, Rankine,t Tyndall, Carpenter, and others are intimately 

 associated with its advancement. In this country Professors Henry J 

 and Leconte have contributed to illustrate the organic phase of the 

 doctrine. 



I cannot here attempt an estimate of the respective shares 

 which these men have had in constructing the new theories ; the 

 reader will gather various intimations upon this point from the 

 succeeding essays. The foreign periodicals, both scientific and lit- 

 erary, show that the question is being thoroughly sifted, and mate- 

 rials accumulating for the future history of the subject. The para- 

 mount claims are, however, those of Joule, Mayer, and Grove. 



* CLATJsnifl, BmooLpn JULIUS IMMANUEL was born at Coslin, Pommern, January 

 22, 1822. He became Professor of Philosophy and Physics in the Polytechnic School 

 at Zurich in 1855, and then Professor of the Zurich University (1857). He was after- 

 wards teacher of Physics and Artillery in the School of Berlin, and then private 

 teacher of the University of that place. 



t BANKINE, WILLIAM JOHN MACQTTOEN was born at Edinburgh, July 5, 1820. He 

 is a civil engineer in Glasgow, a member of the Philosophical Society at that place, 

 and of the Eoyal Society of London. 



t See the article "Meteorology," in the Agricultural Eeport of the Patent Office, for 

 1857. 



See the American Journal of Science for Nov. 1859. 



