various vehement and intestine commotion of the parts among themselves, and in such an one we formerly observ'd the nature of Heat to consist.
EXPER. VII.
In the foregoing Experiment the brisk agitation of the parts of a heated iron was made sensible to the touch; I shall now adde one of the attempts, that I remember I made to render it discoverable to the eye it self. In order to this, and that I might also shew, that not onely a sensible but an intense degree of heat may be produc'd in a piece of cold iron by Local Motion, I caus'd a bar of that metal to be nimbly hammer'd by two or three lusty men accustom'd to manage that Instrument; and these striking with as much force, and as little intermission as they could upon the iron, soon brought it to that degree of Heat, that
