PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 561 



in foundries to arrange a mode of getting rid of the carbonic 

 acid, 



PROJECTILES, 



T. D, Stetson, — The rifling of small arms was so great that 

 ehooting from smooth bores was an almost obsolete idea, but 

 rifling cannons was only in its infancy. An estimate had been 

 made in England that every discharge of the famous Lancaster 

 gun against the Russians cost $500, or <£100, including, of course, 

 the cost of the experiments in the attempt to perfect it. The 

 finishing of the ball by Whitworth's process is very beautiful, 

 but very expensive. He cuts the gun into a six or eight sided 

 bore, and fits the ball to it by accurate finishing of each. The 

 firing of rough shot in a rifled cannon is destructive. He con- 

 sidered the Whitworth the type of perfection, but too expensive 

 for general service. One of the substitutes successfully adopted 

 is the banding of the ball with lead. One officer of the U. S. 

 Army has patented a mode by which wrought iron is bound 

 around the ball, A wrought iron surface would be nearly as 

 destructive as the cast shot, but in this invention grease and 

 leather is also used. He reviewed the history of rifled projectiles 

 from the round ball down to the latest Minnie. A round ball 

 was the least liable to get out of order, and required the least 

 skill, A ball pointed at each end is the most scientific form, but 

 this form of ball is objectionable. The ball hollowed out and 

 chambered at its back or rear end, so as to allow the powder 

 to go inside and expand the metal, causes the ball to spread, and 

 thus to fill the bore and rifle grooves very perfectly. All these 

 are lead balls for small arms. Rifled cannon is yet in a transi- 

 tion state- There has been a number of cannon rifled by our 

 government. The late Secretary Floyd has paid $80 for rifling 

 them. He thought the}" could be done as well at a profit for $10. 



The chairman disagreed with Mr. Stetson, He thought it 

 would cost $80 each to rifle cannon welL 



Mr. Stetson. — All rifle projectiles are longer than the diame- 

 ter. A rifle cannon projectile for a 6 pound gun will weigh about 

 14 pounds. The style in which our Government rifling has been 

 done is not the best. They have rifled them as little as possible, 

 just as the seceding States have seceded as little as they could. 

 He exhibited a ball weighing five pounds designed for a two 

 pound gun. It was a cast iron ball, belted with lead. All balls 

 thus belted are so contrived that by some means the lead is ex- 



[Am. Inst.] JJ 



