1G ON RIFLED GUNS. 



492. f i'05 

 91.07 

 1028790.00 



1029373.'i'12 



Q' + Q" + Q'' 



Thus showing the work performed b}' the forces indicated by the plug experiments to be 

 nearly three times as great as that with which the missile leaves the gun, augmented by the 

 work of friction and of atmospheric resistance. 



Taking one-third of the circumferential, longitudinal, and torsion strains, as they existed 

 at the instant the missile left the piece, in the example of the 100-pounder, these strains will 



stand — ■ 



C=2S07350lbs 

 T = 3703.3 

 h— 10G9.6 



giving the same ratios as before, and from which it is obvious that the failure of rifled guns, 

 with the Parrott twist, must be sought in some cause other than the superadd ition of the 

 pulling and twisting strains to that which acts to split the piece; and, so far as the principles 

 of rifling are concerned, this gun may be made as safe as the common smooth-bore. 



(17) — The values of C, T, and L, will vary with the character of the twist. An increas- 

 ing twist which develops into the arc of a circle, tangent to a rectilinear element of the bore 

 at the bottom of the piece, is suggested in Captain Benton's book on ordnance and gunnery; 

 and the uniform twist is in common use. The equation of the first is 



y 2 = 2 ax — x 3 ; x=p. ¥ 



whence 



L=/-2«./i. ¥+(?.&* = () 



ji = constant 



} (4)' 



o — 



in which a is the radius of the circle. Making y = l, and ¥= — , we have 



4- 2 



1* + /. 



2 



n 



(29) 



(18) — The Equation of the second or uniform twist is 

 (32S) 



