THE ROYAL ARTILLERY INSTITUTION. 
205 
permitted by the designer, who then resorted to the plan of building up 
the component parts of rolled iron, the billets composed of old rails, 
piled alternately with “ puddle bars,” lap or double \ welded into hoops, 
with a species of dove-tailed joint, which hoops were shrunk over one 
another to the requisite thickness. 
The mortar to which the present paper refers, may be described as 
follows:— 
(1) There was the cast-iron base, 30 ins. thick, weighing about T^tons, 
which carried the trunnions, and the flange for holding the longitudinal bars, 
and the chase for the quoin wedges, forming at that side of the axis the 
fulcrum for elevating. A hole 37 ins. in diameter and very slightly coned 
was bored through this base, and enlarged by a recess at the top to 48 ins., 
forming a recess about 13 ins. deep. 
(2) There was a wrought-iron chamber or breech-piece, nearly 70 ins. 
long, formed of a solid forging, much after the manner of the Mersey 
Company's great cannon of the same epoch.* Its largest external diameter 
was 36 ins., reduced by three steps to 24 ins. It was strengthened externally 
by two layers of wrought-iron hoops over the body, and one heavy ring 
towards the mouth, the whole turned with a slight cone, to fit the cast-iron 
base. The chamber proper, which was bored in this, was 48*5 ins. deep, 
and coned from a diameter of about 14 ins. at the cup to 9 ins. at the 
further end. The front was cupped to fit the shell. This piece weighed 
altogether about 7 tons. 
(3) There were three great compound rings of wrought-iron, which, 
together with a muzzle ring, made up the chase 80 ins. long. They were 
built up respectively of 21, 19, and 11 sectional hoops, so disposed as to 
break joint—the inner or A tube of each being in one length, the remainder 
in two or three. The largest of these hoops was 67 ins. in external diameter, 
made out of a bar about 19 ft. long; the smallest was 40 ins. in diameter. 
The greatest thickness of the chase was 16 ins., the least 9 ins. 
(4) A heavy muzzle ring and moulding, having a sectional area of about 
78 square inches. It was turned with a flange to fit over the top of the 
chase. 
(5) Six wrought-iron longitudinal bolts, nearly square in section, con¬ 
necting the above-named ring with the cast-iron base. They had a sectional 
area of 21 square inches each, and were secured at the bottom by gibs, and 
keys (cotters). The top of each bolt was provided with a head, resting on a 
sort of circular iron washer; and to prevent the transmission of a violent 
jar on discharge, a thin ring of wood was interposed between the exterior 
* Two experimental malleable iron guns of 13-inch bore were ordered of Mr. Nasmyth in the 
early part of 1855. One of them was actually welded up, to a weight of upwards of 31 tons, when 
insuperable difficulties in the then state of manufacture compelled its gifted projector, with bitter 
reluctance, to give it up. Messrs. Horsfall were more successful, and in the summer of 1856 com¬ 
pleted and presented to the Government the 13-inch gun of 22 tons now mounted at Tilbury 
Eort. The Royal cypher and a commemorative inscription were cut on this gun by order of Sir 
John Pakington, Secretary of State, in 1868, and it is to be regretted that Mallet’s mortars have 
ndt yet been similarly honored; 
