i8ji.] Modern British Ordnance and Ammunition. 521 



Construction. 



Inches. 



(Length .... 168-5 

 Steel tube {Thickness at {g^J ; ^ 



Breech piece (coiled) .{2^; (exte * rior) ^ 



1 B. Coil, length 57-5 



B. Tube, length 56-5 



C Coil j Len § th 90 



L Diameter (exterior) . . 56 



Palliser shell j Len g th 33 inches, 

 ralliser shell \ Weight ?00 lbs> 



Minimum Service charge, 75 lbs. pebble powder. 

 Maximum battering charge, 95 lbs. ,, 



Intended for Turrets of " Devastation" class. 

 With a proof charge of 130 lbs. of powder, i.e., nearly half 

 as much again as the Service battering charge, the 700- 

 pounder projectile left the muzzle with a velocity of 1370 

 feet per second ; the copper piston in the rear of the shot, by 

 which the pressure of the gas in the interior of the bore 

 is estimated (according to the depth to which it is driven in 

 upon itself), indicating a strain of sixty-four tons to the 

 square inch.* 



This is certainly the finest gun ever turned out by the 

 Royal Gun Factory, to which it does so much credit, and is a 

 signal victory of the F. or cheap construction. It is greatly 



* The Special Committee on Gunpowder and other Explosives, in investi- 

 gating the action of gunpowder, &c, in the gun, make use of three methods: — 

 1. The determination of the time a proje&ile takes to traverse various 

 intervals within the bore of a gun, which is accomplished by means of 

 Captain Noble's chronoscope, which registers by means of eleftric currents 

 upon a recording surface (revolving discs), travelling at a uniform and very 

 high speed, the precise instant at which a shot passes certain defined points in 

 the bore. 2. The velocity outside the bore at the distance of fifty yards from 

 the muzzle, by the Navez-Lenes' chronoscope. 3. The "crusher" gauge, 

 which is alluded to above, which determines the pressure exerted by the gas at 

 various points of the bore (usually five in number). If the "crusher" 

 be inserted in the breech the cylinder is of copper ; if in the chase of the gun 

 where the pressure exerted is comparatively small, it is of an alloy of lead. 



With a piston area of i-6th of square inch, a pressure of 20 tons on the 

 square inch reduces the length of a copper cylinder from 0*500 inch to 0*229 

 inch ; similarly a pressure of three tons on the square inch reduces a lead 

 cylinder from 0*500 inch to 0*240 inch. This " crusher" has been made so as 

 to fit the bush in the base of all Palliser shells. Much better results have 

 been furnished by the " crusher" gauge than by the Rodman system. 



The observations for pressure and velocity independently taken by the three 

 above-named methods, have corroborated and confirmed one another in a 

 remarkable degree. For details see Proceedings of Department of Director of 

 Artillery ; Minutes 27,929, 28,072, 28,768. 



