Polytechnic Association. 879 



gun, but by the reaction of powder gas issuing in small jets through 

 tangential orifices at the circumference of the shot. The shot is to 

 be made hollow, and contain the charges of powder required to 

 rotate it. The objections to Mr. Bessemer's "improvements" are 

 so grave that it may be doubted whether he will carry them into 

 practice. 



Mr. T. D. Stetson — The objection to the use of long guns consists 

 in the impression of the air ahead of the ball. When the gun is 

 short the air can get away laterally without much resistance, but 

 when the tube is long there is a point beyond w T hich the resistance 

 will become considerable. Experiments have shown that shortening 

 the barrel of an ordinary gun from six feet to five will increase the 

 force of the charge. When you fire with steam you can have a longer 

 gun, but with powder you can get all the velocity from ten or fifteen 

 feet that you can ever get. 



The President — The principle of Mr. Lyman's gun is simply this, 

 not to give the ball at first its full velocity. It is the same principle 

 that is applied to the bow and arrow. The bow being upon the prin- 

 ciple of the toggle joint, the swiftest motion is at the end of the 

 motion of the string, so that the velocity is increased all the time until 

 the arrow leaves the bow. Mr. Lyman found that if the full power 

 was applied at first there was danger of the gun exploding. He, 

 therefore, fired a small charge at first, and afterward successive 

 charges, propelling the ball faster and faster until it left the gun. In 

 theory this is very beautiful. A gun made by Mr. Lyman is said to 

 have carried a ball eight miles, which is much farther than was ever 

 before attained ; but Lyman's gun has never been brought into use, 

 although it was invented before our rebellion. 



Dr. P. H. Van der Weyde — Different explosive powers differ 

 chiefly in the time it takes them to burn. Take an explosive powder 

 that is slow in burning and we may use a long gun ; but if it ignites 

 very quickly we must have a short gun. That is the danger of burst- 

 ing a gun in using fulminating powders. It is the virtue of ordinary 

 gunpowder that it burns slowly. If you want long guns you must 

 make the powder burn more slowly. I do not see the necessity of 

 having successive charges. 



The President — It is almost impossible to get powder that will 

 burn slowly enough. 



Dr. Van der Weyde — We may make it burn as slowly as a fuse. 

 We make a pound of powder burn in a tenth of a second, or a twen- 

 tieth, or a hundredth, or a thousandth ; but in that case it would be 



