1822.] Mathematical Principles of Chemical Philosophy. 431 



exist, to produce effects quite the reverse of those which are 

 observed in the phenomena of heat. 



i'' From what has been said, it is evident that were there no 

 resistance to this species of motion, it could be permanent only 

 when the force of attraction is inversely as the square of the 

 distance ; but in a resisting medium ; that is, under the pressure 

 of the atmosphere, and the weight of the parts of the body them- 

 selves, the motion must cease after very few revolutions. Con- 

 sider the weight of the particles alone ; this will give them a 

 tendency to describe a parabola in the higher part of their orbit ; 

 then in the lower, the action of gravity counteracts the tangen- 

 tial force, and ultimately must destroy it ; and even in liquids or 

 gases, it is evident that there is resistance enough almost 

 instantly to destroy all motion ; and as the quantity of resistance 

 thus opposed to the motion of the particles does not depend upon 

 the volume of the hquid, but upon its density, the magnitude, 

 and velocity, of the particles. If two unequal volumes of the 

 same liquid contained in similar vessels be heated to the same 

 temperature, the motion will be destroyed, or the heat will cease, 

 at the same moment in each ; but by experiment, the heat con- 

 tinues longer in the large than in the small volume. Again : 

 since the force of attraction acts only in right lines, which in 

 spheres are directed to their centres, it is quite impossible upon 

 any principle that it can give rise to any sort of rotation what- 

 ever ; since this can be produced only by a force acting obliquely 

 to that of attraction ; for any number of bodies attracting each 

 other, and at liberty to move, will move towards their common 

 centre of gravity only : there is, therefore, no cause whatever to 

 give rise to any motion of rotation. 



But even supposing the motion itself possible, the effects will 

 not coincide with the phenomena of nature. The great pheno- 

 menon to be explained is this : All bodies, whether solid, liquid, 

 or aeriform, are increased in volume by increased heat, and 

 diminished by reduction of temperature ; therefore, the spaces 

 through which the particles move are greater at a high than at a 

 low temperature, and the velocities are supposed to be quicker. 

 Let us see how far this can result from the known laws of curvi- 

 linear motion. Let two 

 bodies A and a describe 

 respectively two circles 

 A B G, a 6 g, with uni- 

 form motions ; the cen- 

 tres of force being the 

 centres S and s of the 

 circles : let AB, a b, be 

 two evanescent arcs, 

 which are described in 

 the same portion of time ; from B and b draw the perpendiculars 



