THE EOYAL AETILLEEY INSTITUTION. 
419 
ACCOUNT 
OF 
PEELIMINAEY TEIAL OF A 600-pr. 13-3 in. M. L. WEOUGHT-IEON, 10 GEOOVED 
SHUNT AEMSTEONG EIFLE GUN, UNDEE THE DIEECTION OF THE 
O. S. COMMITTEE, SHOEBUEYNESS, 19th NOVEMBEE, 1863. 
BY CAPTAIN E. J. BEUCE, E.A. 
This gun was made at Elswick, Neweastle-on-Tyne, and had not been fired (even for proof) 
before the present trial. 
The dimensions of the gun are as follows:— 
ft. in. 
Length over all. 15 3 
Length behind trunnion centre . 6 2'5 
Length of bore . 12 1*25 
Diameter of bore . 0 133 
External diameter over breech . 4 3-5 
„ over trunnion hoop. 4 6-5 
,, at muzzle . 1 9’5 
Width over trunnion ends . 6 2*5 
The gun is built up of eight layers of coiled cylinders barrel inclusive, 
varying in thickness from 2 in. to 2*8 in. The pressure on the back of the 
bore is carried chiefly (as in all the Armstrong guns) by a breech piece, so 
called, forged solid, bored out, and shrunk on the barrel. The breech piece 
of this gun is 6-ft. 8Jin. long, has an outside diameter of 2 ft. 6'3in. and a 
section of 458 square inches. The section of coils operative to resist end 
thrust may be taken as about equal to 125 in. more, making 583 square 
inches in all to meet the strain upon 140", the area of the bore. The barrel 
was made open right through, and the breech end is closed by a wrought- 
iron cylindrical plug fitted into the bore and backed up by a forged wrought- 
iron piece screwed into the breech piece, and faced with a steel-disc. 
The trunnion hoop is made from scrap iron forged under the hammer. It 
is 6 in. thick and 16'5in. wide, and is shrunk on the sixth course of 
cylinders. 
The trunnion hoop and breech piece forgings weighed before machining 
4f tons and 8J tons respectively. 
The outer breech coil was made from a bar 5 in. deep x 4 in. wide in 
section, and 124 ft. long. This bar weighed 71 cwt. It was heated in one 
length, and wound on a drum by a machine at the mouth of the heating 
furnace. The coil was then welded under a 15 ton hammer. This is by far 
the largest coiled cylinder yet made. 
[vol. hi.] Q, Q 
