THE ROYAL ARTILLERY INSTITUTION. 
71 
sponding gutters. To stop the increase of the flaws in the chamber the ring 
was turned every 30 or 40 rounds, bringing a fresh place opposite each flaw. 
After 212 rounds a very slight bulge was observable at the commencement of 
the grooving; the impressions taken shewed its trifling character, and that it 
hardly exceeded the one formed in the 11-inch gun (F) after the same number 
of rounds, which gun however stood 600 rounds more, and remained fit for 
service. 
22. “ After the 212th round it was inferred from marks on the last 
lead ring that some of the recovered projectiles had rubbed the lands as 
well as the grooves. It had been remarked that the impressions of the 
lands and the lead of the projectiles were not of the same width on opposite 
sides. There were two marks on some of them, one wider than the other, 
evidently produced by the same land, but at different instants of the shot's 
passage through the bore, one at the first movement of the shot, the other 
later. It was observed on this occasion that the gauge between opposite 
grooves on the same diameter was less by a line ( T J ¥ or *083 inches) than the 
diameter of the bore.’ These circumstances indicated an irregular movement 
in the bore which could only be attributed to the projectile not having been 
centred at starting. 
“ It became necessary to increase the diameter of the last belt of the 
shot to correct this irregularity; but not to have to enlarge the mould 
in which the lead coating was cast round the shot, six holes were drilled in 
the back part of the projectile in which an equal number of studs were cast, 
having such a relief that the diameter of the hinder part of the projectile 
behind the studs was only three points (0*02 inches) less than the diameter 
of the bore. This arrangement being intended to centre the long axis of the 
shot with the bore in loading as nearly as possible, has sufficed to get rid of 
the rubbing on the end of the shot. However, the inequality of the impres¬ 
sions made by the lands of the rifling continued as before, which proved that 
notwithstanding this improvement, the axis of the projectile did not exactly 
coincide with that of the bore, and that it came into collision sometimes 
with one side, sometimes with the other, while passing through it. 
23. " These irregular movements of the projectile could not be the cause 
of the indents in the bore, because the soft coating of the shot is not able 
to produce them; but when once the formation of dints ceases the stoppage 
of the shot is no longer possible. Irregular movements of a corresponding 
character ought also to occur necessarily in muzzle-loading guns firing 
studded projectiles; only the facts are not so apparant, inasmuch as those shot 
had no soft coating, and consequent^, the effect, if produced, escaped obser¬ 
vation. It may indeed be affirmed that the irregular movement in the bore 
must be greater in muzzle-loading than in breech-loading guns, otherwise it 
would be hard to explain the less accuracy of fire of the former than of the 
latter. 
“Four hundred rounds have been fired with this gun (/) down to the 
present time (April 1865), at the practice ground of Wolkof, and twenty-five 
rounds with a charge of 22 lbs. common powder at Krupp's foundry, 
total 425. 
