800 TRANS. OF THE ACAD. OF SCIENCE. 



the indefatigable zeal of our physicists and natural philoso- 

 phers, and their late researches into the "correlation of 

 forces," have opened, a vein of scientific gold, that promises 

 to reward the explorers with the treasures of knowledge and 

 truth. Since Mayer has calculated the mathematical for- 

 mula for the mechanical equivalent of heat ; since Tyndall, 

 Joule, Faraday, Grove, Helmholtz, LeConte, and others, 

 penetrated deeper into the laws of forces, and their mutual 

 relations, and demonstrated how light, heat, electricity, mag- 

 netism, chemical affinity, and motion, are all convertible into 

 each other, but never destroyed ; there is scarcely a doubt 

 left that the actual indestructibility, but changeability in 

 form throughout nature, will soon be as firmly established of 

 force as it has been proved of matter. 



What are now the most general fornis under which mat- 

 ter and force appear ? 



The most general forms of matter are its solid, its liquid, 

 and its gaseous state. 



The most general forms under which force appears, are : 



1. Physical forces; 



2. Vital force ; 



3. Reasoning force. 



Of the physical forces I consider as the principal ones: 

 Gravitation and chemical affinity, light and heat, magnetism 

 and electricity ; on which certain qualities of matter, such 

 as inertia, molecular attraction, impenetrability, porosity, 

 density, compressibility, expansibility, elasticity, etc., are 

 more or less dependent. 



The six principal physical forces mentioned might be con- 

 densed also into three groups, since every two of them are 

 connected by some natural relationship. Thus, gravitation, 

 with its centripetal and centrifugal force, and chemical 

 affinity work both by molecular attraction and repulsion, 

 though the first tends more to unite similar bodies, 

 the latter dissimilar ones; the first acting more quantitatively 

 and at immense distances, the latter more qualitatively and 

 in close proximity. Thus, light and heat appear to be 

 rather modifications of the same force, than distinct forces 

 mutually dependent. The close relation between magnetism 

 and electricity is still more striking, the essence of both 

 being molecular polarization of matter. 



Our present researches into the correlation of forces have 

 thus far been mostly confined to the physical forces, with the 

 result above stated, that all of them are convertible into each 

 other but cannot be annihilated. 



The following extracts (taken principally from TyndalVs 

 Heat, a new mode of motion, and from Grove's Correlation 



