, TRANSACTIONS OF THE SECTIONS. 179 
On Improvements in Ordnance. By Captain Buakecey, R.A. 
A 16-inch shot would present but 16 times the surface to the action of the air (to 
retard it, or make its flight inaccurate) as a 4-inch shot, and would weigh 64 times as 
much; it would therefore be retarded and blown out of its course but 34, or } as much. 
A gun four times as accurate as a 9-pounder, and with the immense range due to 
the less resistance of the air, would be a powerful weapon on board fast steamers. A 
few 30-inch shell guns would be useful in war, and really conducive to peace if placed 
on the banks of the Thames, the Clyde or the Mersey. If any foreign power quarrels 
with us and suddenly appears with thirty or forty gun-boats armed with one monster 
gun each, he could destroy Portsmouth. None who know Mr. Armstrong’s applica- 
tion of hydraulic power wiil doubt its adaptability to move guns of any size, and 
-with little human labour. Large guns require more strength than small ones, as the 
‘powder occupying in each the same proportional space, the small shot moves in say 
sap of a second a certain number of inches, the large shot in the same time moving 
fewer inches, so that at the end of that time the gas in the small gun would have 
much more proportionate room to expand in, and would therefore press less on the 
gun than in the large one. Added to this, the large shot would require more time to 
get its velocity, and the pressure must remain on the gun so much longer. May not 
_ the dime a material can bear a tension be an element worthy of experiment; and may 
not cast iron bear a pressure during 54, of a second, which if continued during half a 
second would destroy it? I believe the sudden and short strain caused by the explo- 
_ sion of gunpowder to be less, not more injurious, as is generally thought, than an 
equal strain applied gradually but left longer. However, a 32-pounder is the limit of 
cast-iron guns of the present shape, any larger than that being unsafe with full charges. 
Adding thickness to the metal would give little additional strength. Professor Bar- 
low calculates that a cylinder one inch thick, and one inch in internal diameter when 
strained, stretches only } as much in proportion outside as inside, the cross section 
remaining equal, so that the interior diameter being stretched to 1 Xz, the exterior, 
instead of becoming 3 X54, (as it would if the outside layer ‘‘pué out” an equal 
strength to the inner, according to the law “ut tensio sic vis’), becomes only 8+4 
Of pho OF 8-++-acbs- The cross section being (8+s5¢%55)°=9-+535 minus (14+ 7955)” 
_ =1+ 1,3 the difference, 8 round inches, being the same as when not strained, or 
(3?—1?). 
Uf with the present thickness the outside docs but 3 its duty, we can expect but little 
additional strength from adding to it; Professor Barlow arguing that the strength 
decreases as the squares of the distances from the centre. The same law puts a limit 
to the size of brass or cast steel guns, or of wrought iron if in one welded mass. 
I would suggest for guns up to 10 inches a shape very like the present, but the 
outside at the breech strengthened with two layers of thin wrought-iron cylinders put 
on very hot, and hammered so that the outside shall be fully strained when the gun 
is fixed. One I made so stood 605 rounds, all with double charge, and the last 158 
rounds loaded to the muzzle. This is evidently greater strength than is required for 
_ anything under 10-inch guns. Above that, I think, with a cast-iron cylindrical centre, 
that either rod-iron wound round at a great heat and welded, layer over layer, but 
each in cooling taking a permanent strain, or else iron wire wound round it, each 
_ layer having a greater initial strain than the one under it, would be the best way : we 
thus get all the fibre in one direction, 
__ Mr. Armstrong of Newcastle made a gun of a solid steel centre, with bar iron 
coiled round it and welded. This gun has stood some thousands of rounds. I dis- 
_ covered early in 1855 that Mr. J. Longridge, C.E., agreed very nearly with me in 
‘opinion, having arrived quite independently at his conclusions, and since then we 
have been working together. I exhibit some brass cylinders strengthened with wire, 
which he experimented on; the strain cannot have been under 56 tons per inch on 
some of these, reckoning brass and wire, or at least 70 tons an inch on the wire, as 
there the strength lay. . This would make very serviceable field howitzers; such 
howitzers need not weigh over 8 cwt. 
__ If we do not possess the most efficacious weapons possible, we shall find ourselves 
‘overpowered some day. Any foreign power couid secretly prepare a flotilla of gun- 
boats, and manufacture the large guns to destroy our fleets and seaports immediately 
after a declaration of war. 
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