278 Mr. Thrapath on the Causes, Laws, and principal [ApRii,^ 



inanimate bodies could act on each other at a distance without 

 some other means than that of a mere tendency, or incHnation, 

 in them to approach, would appear so strongly unphilosophical', 

 and the apparent coincidence of several phenomena, with con- 

 <ilusions 1 had drawn from my notions of gravitation, so very 

 seducive, that I could not avoid thinking the views I had taken 

 were tolerably correct ; and that there was only wanting the 

 direction of some happy idea, which patient perseverance might 

 possibly attain, to set the whole in a clear and irrefragable light. 

 Thus between hope and despair, between unceasing attempts 

 and mortifying failures, I continued until May 1814, at which 

 time my ideas of heat underwent a complete revolution. Previous 

 to this time I had conceived heat to be the effect of an elastic 

 fluid ; and on this supposition had repeatedly attempted to 

 reduce its laws to mathematical calculation; but uniform disap- 

 pointment at length induced me to give this hypothesis a careful 

 investigation, by comparing it with general and particular phaeno- 

 mena. The result of this investigation convinced me that heat 

 could not be the consequence of an elastic fluid. At the time I 

 was making this comparison, I took every opportunity of exa- 

 mining how far the other hypothesis (which until now I had 

 forgot was sanctioned by the names of Newton and Davy) 

 agreed with phainomena, and was so well pleased with its sim- 

 plicity, and the easy, natural manner in which the different 

 phaenomena seemed to flow from it, that I regretted having 

 neglected it so long, and determined to consider it more atten- 

 tively. A difficulty, however, soon appeared in the application 

 of this theory of heat to gaseous bodies, which I had some 

 trouble to conquer ; for as 1 still adhered to the hypothesis of 

 gases being composed of particles endued with the power of 

 mutually repelling one another, I could by no means imagine 

 how any intestine motion could augment or diminish this power. 

 Here then I was involved in another dilemma ; but after 1 had. 

 revolved the subject a few times in my mind, it struck me that 

 if gases, instead of having their particles endued with repulsive 

 forces, subject to so curious a limitation as Newton proposed, 

 were made up of particles, or atoms, mutually impinging on one 

 another, and the sides of the vessel containing them, such a 

 constitution of aeriform bodies would not only be more simple 

 than repulsive powers, but, as far as I could perceive, would be 

 consistent with phenomena in other respects, and would admit 

 of an easy application of the theory of heat by intestine motion. 

 Such bodies I easily saw possessed several of the properties of 

 gases ; for instance, they would expand, and, if the particles be 

 vastly small, contract almost indefinitely ; their elastic force 

 would increase by an increase of motion or temperature, and 

 diminish by a diminution; they would conceive heat rapidly, 

 and conduct it slowly ; would generate heat by sudden com- 



