BURSTING OR HEAVY GUNS. 
197 
into the cause of the accident, and until their decision be known it is obviously 
premature to express any opinion. It is certain that rapid local ignition and want 
of facile diffusion of flame is extremely apt in large and dense charges to give rise 
to oscillations productive of extraordinary intensifications of pressure, and it is also 
certain that the calculated strength of the 100-ton gun at the point of fracture is 
far in excess of what a normal pressure would demand; but you had better hear 
what the Italian Commission makes out before committing yourself to further 
criticism. 
Noble is not here at present, and therefore I cannot consult him, but will do so 
on his return. 
The quality of the powder for heavy guns, as well as the mode of igniting it, 
becomes more and more critical as we advance in dimensions, and there is great 
want of adequate experience on the subject. Nothing, in fact, wants investigation 
so much as this powder question, and until we arrive at more definite conclusions 
we cannot hope to be altogether free from accident. My own leaning is in favour 
of prismatic powder, which affords the advantage of tubular flame space, and 
occupying little room, thereby allowing the flame to pass freely both through it 
and round it; but for very big guns I think the prisms should be larger, so as to 
reduce the aggregate surface" to be ignited and lesson the primary production 
of gas. 
Yours truly, 
W. Gr. ARMSTRONG. 
Capt. Orde Browne. 
This Shoeburyness experiment is known to Gen. Younghusband and 
other officers present. Therefore we have, apart from Sir WillianPs 
statement, reason to contemplate the possibility of violent wave action, 
at all events, if even a small part of the charge were broken up. 
Let me remind you, however, that not only is the charge devoid of 
a central tube, but it consists of progressive powder. The last time 
I had the honor of addressing you, I spoke of this powder as very 
excellent for an individual result, but surely peculiarly liable to variation 
—consisting of a mixture of slow-burning and quick-burning powder, 
so arranged that tke slow-burning should be consumed first; but sup¬ 
pose the grains to be at all broken, or even imperfectly formed, the 
quick-burning powder might be exposed to ignition before the proper 
time, and then a great effect might be caused. 
At Spezia, in the trials in 1876-7, in the early 100-ton gun trials, 
275 lbs. of W.A. P 3 powder gave 1542*8 ft. velocity, with a pressure of 
21*4 tons. In 1879, in the enlarged gun, 551 lbs. of F. powder gave 
1671*6 ft. velocity, with a pressure of 20*38 tons. 
This was an excellent result; but suppose the F. powder to have its 
condition modified sufficiently to bring it to the condition of W.A. P 2 
powder, the result produced would be simply that the charge would 
be doubled. 
If, then, we consider the recent effect of axial vent with no ignition 
tube, altered grain of powder, and the complex character of the F. 
powder, there is abundant cause for producing an abnormal strain. 
Now, we ought to consider the position of a private firm, manu- 
