CJid on fQ Tlxpansion of Moist Air. 435 



ictidrvis not the effect of the action of the indi- 

 virtual particles, which is to mo inconceivable. 

 Yet It is upon this the author fixes the main 

 spring of his argumentation. The transparency 

 of the atmosphere (page 309) merits no notice. 

 An' experiment is brought forward at page 313, 

 to Jirove that vapour flowing through air open 

 to the atmosphere actually expands the air ; 

 on which my observations are given at page 413. 

 The most important observation in both essays, 

 however, 16 at page 421, where Mr. Gough 

 clearly demonstrates that he has been all the 

 while combatting a chimera : by insisting that 

 u})on my theory vapour cannot move the par- 

 ticles of air unless its force is equal to atmo- . 

 spheric pressure, he makes it manifest he does ^ 

 not understand the fundamental principle. I 

 never made it a part of my system to conceive, 

 that if a particle of any one gas was actually ia 

 contact and pressing like an inelastic body on 

 a particle of another kind of gas, that it pre- 

 vented the simultaneous action of a kindred 

 proximate particle : Tlius, if three equidistant 

 particles of gas j, cr, tf, in the same horizontal 

 tine are kept in equilibrium by the action of a 

 surrounding system of particles ; and if any 

 particle, (;, of another gas be in contact and 

 made to press on the middle particle a, in the 

 horizontal direction ; I never imagined that 

 3 I 



