M. Seguin on the Effects of Heat and (ff Motion. ^81 
that each body, though it appears at rest, has really a certain 
quantity of motion, whose measure will be a function of the mass^ 
and the velocity of the molecules in motion. 
Upon these suppositions, it is obvious, that, during the im- 
pact of two bodies, all the quantity of motion which is not em- 
ployed in giving the body which is struck a motion of transla- 
tion, will go to augment the quantity of interior motion which it 
possesses ; and if this motion takes place in circles or ellipses, the 
parts will recede from the centre of attraction, and the body will 
increase in volume. In this state it will have a tendency to trans- 
mit the excess of motion which it possesses, to bodies which are 
near it, or to parts which it will emit in greater number, in 
following the same Jaw. 
If the quantity of motion is so great, that the attraction of 
the molecules can no longer be in equilibrio with their angular 
velocities, the body will remain in the gaseous state, till it has 
transmitted to other bodies the excess of velocity which it pos- 
sesses. 
The particles, in continuing to circulate at a distance, or in 
detaching themselves from bodies with different velocities, may 
make different impressions upon organised bodies, viz. that of 
light, if the velocity is sufficiently great to make it traverse the 
humours of the eye ; that of heat or flame, if their number is 
sufficiently great to put in motion or evaporate the organised 
parts, and that of both heat and dame, in the two cases united. 
Bodies, in short, being subject to circulate in circles or in 
ellipses, ought to group themselves together, according to the 
simplest law of solids, inscribed in these two figures. 
It is not difficult to observe the connexion which this theory 
has with magnetic phenomena, as well as the objections which 
may be made to it ; but I shall forbear entering into more 
ample details, lest I should abuse the patience of the Society, 
if it should deign to notice an inquiry, which has for twenty 
years been the subject of my reflexions, assisted by those of the 
disciples of M. Montgolfier, who, like me, have had the advan- 
tage of living near him. I shall now conclude, by pointing out 
the application of this new theory to four facts, selected fromt 
the crowd of those which it may serve to explain. 
s 
