THE ROYAL ARTILLERY INSTITUTION. 
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was assumed, on the evidence of the Eodman pressure-gauge, that 43 lbs. 
of Prussian cannon-powder was equal in its effect upon the gun to 53 lbs. 
of prismatic powder; and therefore all the rounds fired with charges of 
43 lbs. and upwards of Prussian powder, were included in the test for 
endurance of the Krupp gun. 1 Now, it is quite possible that 43 lbs. of 
Prussian powder are equal in pressure to 53 lbs. of prismatic, although we 
are not prepared to accept the indications afforded by the Eodman gauge 
as trustworthy evidence upon this point; but if it be so, then, as the 
English pow T der is admittedly much more destructive than the Prussian, and 
as the English gun fired throughout 43 lb. charges, it follows, on the 
evidence of the Prussian instruments and by the arguments of those who 
conducted the experiments, that the test advisedly adopted for the English 
gun was much more severe than that adopted for the Krupp gun. 
Einally, the endurance test of the Prussian gun was conducted in, to say 
the least, a most extraordinary manner. Captain von Doppelmair states 
that, “ after 430 rounds, a guttering, 22 millimetres long, appeared at the 
bottom of the vent. The metal at the bottom of the vent was on this 
account removed spherically to a depth of 75 millimetres; but as the 
guttering again appeared after the subsequent 30 rounds, the metal was 
further removed to a depth of 25 millimetres. 2 At the 176th round, the 
breech-piece was also damaged, as before described, by a few rounds of 
English powder fired experimentally, 3 and had to be replaced with one of 
“ somewhat different construction, and a new Eroadwell ring.” 4 Captain 
von Doppelmair also states that some further partial failure of the second 
Eroadwell ring occurred after 445 rounds had been fired from it. 5 Eurther, 
after 662 rounds, a serious crack, 267 millimetres long, ultimately appeared 
in the chamber of the gun, 6 which was developed another 90 millimetres 
by 14 more rounds. 7 “ After this,” says Captain von Doppelmair, “ the 
trial of endurance, which the gun had hitherto sustained in the most 
brilliant manner, was discontinued.” 8 
The “Times” correspondent gives a somewhat different account of these 
proceedings. He says:—“ If our information be correct, the wedge, or 
breech-loading apparatus, had to be changed so long ago as September 29. 
After the firing on that day, a crack was discovered at the base of the old 
upper vent. Mr. Krupp's workmen were allowed to cut away the surface 
of the bore, at the seat of the incipient danger. Part of the breech-loading 
apparatus was again renewed on October 15. After the practice on the 
same day, the crack appeared again, and was again cut out. On Nov. 19 
there was a considerable escape of gas. Before firing on November 21, 
the whole breech-loading apparatus was renewed, both Broadwell ring and 
wedge. On December 3, so serious a crack appeared, that the chief advo¬ 
cates of the gun desired that no further experiments should be made with 
it.” 9 
1 Doppelmair, p. 53. 2 Ibid. p. 53. 3 Ibid pp. 12,13. 
4 Ibid. p. 54. 6 ibid. p. 64). 
6 Ibid. pp. 54, 55. 7 ibid. p. 54. 
8 Ibid. p. 54. The gun subsequently endured thirty-six more rounds with no further increase 
of the crack, and it was then sent back to the factory for repair, pp. 85, 86. 
9 “ Times,” January 23, 1869. 
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