430 



TRANSACTIONS OF THE AMERICAN INSTITUTE. 



at the place where a sharp edged collar is placed to prevent a soft metal 

 band from being- forced out of the gun in advance of the shot. The soft 

 metal band will take the grooves and give the shot the rifled motion, but 

 will not hinder the shot in its passage through iron plating, against which 

 it is projected. When used as a shell, it is intended to ignite the powder 

 it contains by the heat of compression resulting from the blow against the 

 plating. The small inclined and inclosed tube is intended to contain com- 

 mon powder, and it is inclined toward the front of the shell that the com- 

 pression may not entirely close the passage to the powder contained in the 

 cavity of the shell, but rather only close its front end first. 



GREAT CAST IRON GUNS. 



The last gun I shall describe, exhibits the result of my efforts to produce 

 I cheap gun of larger size than has been before produced, constructed, how- 



ever, with full knowledge of all the effects of combustion of the powder by 

 pressure, as laid down by ordnance officers in books heretofore, and the 



