For the two facts (I) that such great motion is produced in a cannon and in a mine and that none of the visible bodies that surround them is in a state of agitation sufficiently great to produce this motion, constitute certain proof that there are other invisible and insensible bodies that have at least as much agitation as the cannon ball, but that, being very subtle and delicate, can by themselves pass freely through the pores of the cannon without rupturing them, before it fires,.e.