the Heat excited by Friction. 493 



bar to which the blunt borer is fixed is represented 

 broken off at m. 



Fig. 4 is a perspective view of the wooden box, a sec- 

 tion of which is seen in the foregoing figure. (See^, h^ 



*> *, Fi g- 3-) 



Fig. 5 and 6 represent the blunt borers, joined to the 



iron bar m, to which it was fastened. 



Fig. 7 and 8 represent the same borer, with its iron 

 bar, together 'with the piston which, in the experiments 

 No. 2 and No. 3, was used to close the mouth of the 

 hollow cylinder. 



END OF VOL. I. 



Cambridge : Electrotyped and Printed by Welch, Bigelow, & Co. 



