i873-] Recent Changes in British Artillery Materiel. 337 



ignored. They hope the manufacturers may succeed in 

 overcoming the difficulties thus indicated, and enable this 

 explosive, so useful for many purposes, to be admitted with- 

 out restriction. 



" The committee have no hesitation in recording their 

 opinion that a safe and unobjectionable nitro-glycerine com- 

 pound, possessing valuable explosive properties for many 

 useful purposes, and fully meeting all the requirements of 

 quarry owners, can be manufactured, transported, and stored 

 in this country." 



With regard to powder, it has been found that the very 

 heavy charges of pebble powder, although they may not 

 give the same pressures as the former charges of rifle large 

 grain, still really do much more real damage to the guns, 

 and will render the necessity of re-venting and indeed of re- 

 tubing the guns much more frequent. 



II. The last experiment with regard to the constant 

 variations in the strength of gunpowder has led to a re- 

 consideration of the lately-existing proof regulations (one 

 and a quarter times highest service charge) for heavy guns. 

 It is found necessary, in consequence of the unsatisfactory 

 discrepancies in amount of pressure produced by a com- 

 paratively small increase in the charge, that proof charges 

 should be larger than service ones, in order to ascertain 

 whether the gun possesses superabundant strength to resist 

 the effects of powder which may be more than ordinarily 

 violent; and therefore the proof of guns should be con- 

 ducted upon the same general principles as heretofore, viz., 

 by using the service projectile and a charge somewhat in 

 excess of the service one, but the amount of excess need 

 not be so great as of old, that the gun may not be subjected 

 to severe local pressures or strains which might permanently 

 weaken or otherwise injure the structure of the gun under 

 proof. The proof charge of the 12-inch gun of 35 tons 

 will, therefore, now be as follows : — First round no lbs., 

 and second round 115 lbs. of pebble powder; the projectile 

 of service weight being used in each case. Experiments 

 are now being carried out to determine the proportionate 

 increase of proof over service charge for 8, 9, 10, n, and 

 12-inch (25 tons) guns. It may here be noticed that the 

 learned Professor Bashforth is disposed to question the 

 very discordant results obtained by the committee as to the 

 measurements of the variation of powder-pressure, as regis- 

 tered by the crasher-gauges and the chronoscopes of Schultze 

 and Noble, on whose results little reliance is to be placed in 

 consequence of their records being received on the surfaces 



