PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 367 



from a fair distance would entirely destroy its operation. The 

 advantage claimed for the steam gun is, that it requires so few 

 men to do the work. But in w^arfare there are always plenty of 

 men to fight, if we can only find the money to pay them. 



The ball will have a rotary motion, upon leaving the disk, in 

 consequence of the greater momentum of that part of the ball 

 which at that moment happens to be farthest from the centre of 

 the disk. Military authorities say that the bullet should have 

 an initial velocity of 12 to 1,500 feet. With light rifles the 

 speed probably reaches 2,000 feet. With such speed as that, the 

 centrifugal gun falls into the background. 



Mr. Stetson. — The tendency of modern improvements is 

 to enable us to throw projectiles farther with a less initial 

 velocity. The charge of powder is somewhat reduced ; yet, in 

 consequence of the elongated and pointed form of the shot, there 

 is less atmospheric resistance, and the projectiles go as far and 

 produce as much effect at the distance of 1,000 yards as those of 

 the old shape did with a greater initial velocity. Probably the 

 velocity from some rifled pistols does not exceed 600 feet. The 

 charge of powder that instead of being one-fourth to one-third 

 the weight of the ball, is so much reduced, that, with the Ilotch- 

 kiss projectile, a twelve pound ball requires but thirteen or four- 

 teen ounces of powder, ranging from half a mile to a mile very 

 accurately. 



The expansive force of gunpowder is very great, having 

 been shown sometimes to amount to 100,000 lbs. to the square 

 inch.* No such force as that of gunpowder can be produced 

 by steam. Nor can we produce the centrifugal force due 

 to such pressure without destroying the machine. We can only 

 obtain a comparatively small velocity. 



In order to throw a projectile with a given velocity, a force is 

 required equivalent to lifting it a certain height, independent of 

 friction, for that velocity will be expended in raising it that 

 height ; or, inversely, if it is allowed to fall from that height, in 

 a vacuum, that velocity will be produced. To produce a double 

 speed in any mass requires a quadruple power, the power required 

 being in the ratio of the square of the velocity. It is thought 

 by some that we may be able, with centrifugal guns, to throvsr 

 bullets at the initial, velocity of six hundred feet, which will 

 kill at short ranges. But we cannot throw a stream of bullets, 



•Count Renaford's experiments make the force of coafined gunpowder 500,000 lbs. — J. R, 



