492 Inquiry co7icerning the Source of 



DESCRIPTION OF THE FIGURES. 



FIG. I shews the cannon used in the foregoing ex- 

 periments in the state it was in when it came 

 from the foundry. 



Fig. 1 shews the machinery used in the experiments 

 No. I and No. 2. The cannon is seen fixed in the ma- 

 chine used for boring cannon. W is a strong iron bar 

 (which, to save room in the drawing, is represented as 

 broken off), which bar, being united with machinery 

 (not expressed in the figure) that is carried round by 

 horses, causes the cannon to turn round its axis. 



m\'s,2i strong iron bar, to the end of which the blunt 

 borer is fixed ; which, by being forced against the bot- 

 tom of the bore of the short hollow cylinder that re- 

 mains connected by a small cylindrical neck to the end 

 of the cannon, is used in generating Heat by friction. 



Fig. 3 shews, on an enlarged scale, the same hollow 

 cylinder that is represented on a smaller scale in the fore- 

 going figure. It is here seen connected with the wooden 

 box \g^ h, z, k) used in the experiments No. 3 and No. 

 4, when this hollow cylinder was immersed in water. 



p, which is marked by dotted lines, is the piston 

 which closed the end of the bore of the cylinder. 



n is the blunt borer seen sidewise. 



d^ e, is the small hole by which the thermometer was 

 introduced that was used for ascertaining the Heat of 

 the cylinder. To save room in the drawing, the cannon 

 is represented broken off near its muzzle ; and the iron 



