THE ROYAL ARTILLERY INSTITUTION. 
335 
THE THEORY OF GUN ARCHITECTURE. 
BY 
CAPTAIN F. S. STONEY, E.A., 
CAPTAIN INSTEUCTOE, EOYAL GUN PACTOEIES. 
When rifled ordnance first came into fasliion and the artillery service 
required guns in which the maximum of strength would combine with the 
minimum of weight, inventions good, bad, and indifferent poured into the 
War Office, and the proposers generally adduced theories in support of their 
several systems. Mathematicians, too, turned their attention to the problem, 
so that altogether a good deal—judging by quantity—has been written and 
spoken on the subject of late years. The present paper is an attempt to 
explain briefly the science of constructing guns, and to shew by reference to 
modern artillery how far theory is carried out in actual practice:— 
The power of any homogeneous tube or cylinder to resist pressure from 
within is not proportional to its thickness. A cylinder for an hydraulic 
press with a thickness equal to half the diameter of the piston is said to be 
nearly as strong as one ten times as thick. - * Guns are no exception to the 
general rule. The sides of the 13-inch S.S. mortar are twice as thick as 
those of the 13-inch L.S. mortar, but the former piece is far from being 
twice as strong as the latter. 
Several men of science who investigated the problem agree that no 
POSSIBLE THICKNESS CAN ENABLE A CYLINDER TO BEAR A CONTINUAL 
PRESSURE PROM WITHIN GREATER ON EACH SQUARE INCH THAN THE TENSILE 
STRENGTH OE A SQUARE INCH BAR OE THE MATERIAL, that is to Say, if the 
tensile strength of cast-iron be 11 tons per inch no cast-iron gun however 
thick could bear a charge which would strain it up to that point, for on the 
first round the interior lamina would be ruptured before the outer portion 
could come into play, and every succeeding round would tend to magnify 
the evil. 
The matter is not difficult to understand. Take for example a section of the 
10-inch cast-iron gun where the thickness of the metal is 5 inches, and assume 
that the amount which the metal will stretch before it breaks is a thousandth 
part of its length. Now supposing a pressure could be communicated with 
* Holley. Ordnance and Armor, p. 238. 
