EXPER. VI.
And it will be convenient to begin with an instance or two of the Production of Heat, wherein there appears not to intervene any thing in the part of the Agent or Patient but Local Motion, and the natural Effects of it. And as to this sort of Experiments, a little attention and reflection may make some familiar Phænomenon apposite to our present purpose. When, for example, a Smith does hastily hammer a Nail or such like piece of iron, the hammer'd metal will grow exceeding hot, and yet there appears not any thing to make it so, save the forcible motion of the hammer which impresses a vehement and variously determin'd agitation of the small parts of the Iron; which being a cold body before, by that superinduc'd commotion of its small parts, becomes in divers senses hot; first in amore
