We find aIfo D that Attrition, if it be 

 any thing vehement, is wont to pro- 

 duce Heat in the folideft bodies > as 

 when the blade of a Knife being 

 nimbly whetted grows prefently hot. 

 And if having taken a brafs Nail, 

 and driven it as far as you can to the 

 end of the ftick, to keep it faft and 

 gain a handle, you then ftrongly rub 

 the head to and fro againft the floor 

 or a plank of wood, you may quick- 

 ly find it to have acquired a Heat in- 

 tenfe enough to offend , if not burn 

 ones fingers. And I remember,that 

 going once in exceeding hot weather 

 in a Goach , which for certain rea- 

 (bns we caus'd to be driven very faft 3 

 the attrition of the Nave of the 

 Wheel againft the Axel-tree was fo 

 vehement as oblig'd us to light out of 

 the Coach to (eek for water, to cool 

 the over-chafed parts , and ftop the 

 growing mifchief the exceflive Heat 

 had began to do. 



The vulgar Experiment of ftrike- 



ing fire with a Flint and Steel fuffici- 



ently declares^ what a heat in a trice 



E 4 may 



