196 
BURSTING OP HEAVY GUNS. 
As to tlie steel tube, no doubt interests are involved in it which 
make it wrong to speak certainly of its quality before we hear more. 
Should the steel tube turn out to be unsound, then unquestionably 
there is cause for blaming the material of the gun. Of this, of course, 
we cannot judge at present. 
Supposing that there is no fault to be discovered in the steel, can we 
see how any extraordinary strain could fall on the gun ? Air spacing 
would produce a great diminution of pressure. It was not double- 
loaded, and could not well jam, as it has no studs, and I do not know 
that it has paper wads. A possible cause lies nearer at hand, though 
until, comparatively recently wholly unsuspected. 
The charge consists of 551 lbs. of Fossano progressive powder , and 
there is ho central tithe up the cartridge , and the gun has an axial vent. 
UJow, I have received two letters from Sir W. Armstrong, in one of 
which he fells me that in a recent Elswick experiment, by firing an 
untubed cartridge by an axial vent, the pressure was increased from 
18 to over 5.0 tons. 
N E WC ASTLE- ON-T YNE, 
lltli March, 1880. 
My dear Sir, 
We have little information about the failure of the 100-ton gun beyond 
what has appeared in print. The gun was abundantly strong at the point of frac¬ 
ture to resist any legitimate pressure, and I have little doubt that the cartridge and 
mode of lighting by a rear vent are in fault. In some recent experiments of our 
own we had the pressure exalted from about 18 to over 50 tons per square inch, 
fiy Igniting at a rear vent an untubed cartridge, such as the Italians have been 
using. -The extra pressure is all wave action, and chiefly takes effect longitudinally, 
thereby fending to tear the gun asunder. A small variation in the quality of the 
powder, ‘or a slight admixture of pulverised or broken lumps, seems sufficient to set 
up a localised ignition which throws the whole mass into violent oscillation. 
The' proper management of the huge charges now used, so as to obtain invariable 
exemption from this dangerous action, is, in my opinion, the chief unsolved problem 
in regard to monster artillery. 
Yours very truly, 
W. G. ARMSTRONG. 
P.S.—It occurs to me to mention that within the last few days an 8-in. M.L. 
gun of ours was fired at Shoehury with charges of 105 lbs. pebble powder, which 
gave 18 tons pressure in the bore. By way of experiment, cartridges containing 
a proportion of R.L.G. powder were tried, and it was found that with only 5 lbs. 
of this smaller powder, mixed with 100 lbs. of pebble, the pressure on the crusher 
gauges rose to 30 tons, the velocity of the projectile remaining almost the same; 
so that the extra 12 tons was all wave action. This was with a top vent, and the 
difference would have been far greater with an axial vent. 
My dear Sir, 
Newcastle-on-Tyne, 
16tli March, 1880. 
It is always risky to pronounce judgment on a subject while it is under 
investigation. An Italian Commission of highly competent persons, who have all 
the facts before them and have the gun to refer to, are now prosecuting an enquiry 
