THE 80-TON GUN. 
845 
as crucible steel, being melted in about 240 small crucibles, whose 
contents are run into a large mould. The process is very expensive 
and eminently unscientific—having^ indeed, nothing to recommend it 
but its success. This quality has, however, undoubtedly been attained 
by Messrs. Firth. 
It is not requisite for me to describe minutely the details of the 
manufacture of our ordnance; I will merely indicate the successive 
processes of building up the 80-ton gun. Over the rear end of the 
steel tube is shrunk a very powerful coil, called the breech-piece. This 
is made of a single bar, 12 ins. thick from inside to outside, hammered, 
rolled, and coiled—forming a cardinal point in the mode of construc¬ 
tion. The cascable is next screwed in, so as to abut firmly against the 
solid end of the tube, and the B coils are then shrunk on into their 
places. The ponderous C coil, carrying the trunnions, comes last, and 
is in truth a marvellous piece of forging. It was made of two coils— 
one outside the other—and was 18 ins. thick. These coils were welded 
together under the 40-ton hammer. It should be stated that, in order 
to obtain greater certainty of soundness and ease of manipulation, both 
the breech-piece and the C coil were made in two pieces, which were 
welded together, end to end; care being taken that the weld of the 
breech-piece was not inconveniently near that of the C coil. 
The sketch appended gives a clear idea of the successive processes, 
and the Table A shows the weights of the forgings, both in the rough 
and after finishing. It will be noticed that the total amount of iron 
used is twice that of the gun. This waste is due to the necessity for 
turning off the surfaces and ends of the coils, so as to obtain a fine 
clear metal, free from flaws. The metal turned off is, of course, used 
again. 
TABLE A. 
Detail of Weight of Material for 80 -ton M.L.R. Gun. 
Name of piece. 
A tube (steel) 
Breech piece 
Cascable . 
1 B coil _ 
2 B coil . 
B tube . 
Trunnion .... 
Ccoil .’.. 
Size of bars. 
Length of 
bars. 
Weight of bars. 
Weight of 
iron used in 
Finished weight 
of parts of 
gun. 
gun. 
tons. cwt. qrs. 
tons. cwt. qrs. 
tons. cwt. 
qrs. 
16 
10 
0 
7 
13 
0 
( 12 x 10 x 8^- 
{11 x 10 x 8£ 
50 
150 
7 
21 
10 
18 
O O 
29 
8 
0 
17 
10 
0 
1 
7 
0 
0 
19 
0 
fS|x6ix5| 
86 
6 
9 
86 
6 
9 
of 
27 
6 
0 
13 
8 
0 
L !> 
192 
14 
8 
o) 
C 8^ x 6 g- x of 
30 
2 
5 
0) 
] 7% x 6| x 5& 
32 
2 
4 
°f 
6 
5 
0 
4 
3 
0 
(7 x 6 x 5 
31 
1 
16 
o) 
(7|x6 x 5f 
60 
4 
2 
2") 
■<7 x 6 x 5 
40 
2 
6 
2 f 
8 
1 
1 
3 
8 
0 
(.6 x4^x4| 
40 
1 
12 
l) 
18 
0 
0 
f 8^x6ix5f 
173 
12 
19 
< 8| x 6| x 5f 
173 
12 
19 
2 f 
57 
19 
0 
34 
5 
0 
(. 9| x 8| x 7 
300 
32 
0 
oj 
164 
16 
1 
81 
6 
0 
