THE 80-TON GUN. 
475 
Still, tlie 80-ton gun is by no means a bad weapon, as far as it goes; 
and we will now consider its powers as realised up to the present stage 
with relation to the problem originally propounded to the designers, 
and observe how its prowess has been gradually augmented at each 
successive stage of its development. 
TABLE F. 
Eound. 
Calibre. 
Maximum 
pressure. 
Mean 
pressure. 
Total 
energy. 
Penetrating 
power at 
1000 yds. 
ins. 
ft. tons. 
ft. tons. 
ft. tons. 
ft. tons. 
17 . 
14-5 
24-9 
23-0 
20,058 
380 
6 . 
15-0 
24-8 
23-8 
20,705 
383 
30 . 
15-0* 
23-4 
22-4 
23,205 
433 
48 . 
15-0f 
23*3 
22-5 
24,493 
457 
15 . 
16-0* 
21-8 
20-4 
26,740 
466 
* Air spaced. f Air spaced and chambered. 
These rounds have been selected as the highest in power at each 
stage which could be fixed upon as service rounds—that is, in which 
no pressures of an inadmissible character are recorded. 
For purposes of experiment, where the brands of powder are inti¬ 
mately known and their variations can be depended on not to exceed 
safe limits, it is convenient to consider rather the mean pressure in the 
chamber than an isolated maximum; but for firing under service con¬ 
ditions this method of observation would not be admissible, and hence 
I have discarded it in the above summary. The last column shows 
that the great stride in the progress of the gmFs powers has been 
made by the introduction of the air-space principle. The other novelty 
—the enlargement of the chamber—has also gained great success, 
when it is considered that the increase of diameter was too small, and 
moreover that the chamber was too short to permit the full develop¬ 
ment of the principle. 
It is in contemplation to enlarge the chamber to a diameter of 18 ins. 
on the return of the gun from Shoeburyness, where it will speedily 
exhibit its powers in a practical manner; but time presses, and this 
farther development cannot be carried out at present. In the mean¬ 
while, taking round 15 (Table F) as our best result, and bearing in 
mind that with our present knowledge of powder there is no difficulty 
in repeating any result once gained without sensible difference, we 
proceed to investigate the question of penetration. Working out the 
two formulas adopted in the previous paper on this subject as types, 
it appears that at 1000 yds. the 1703-lb. projectile will perforate 
according to 
ins. 
Capt. English, R.E.. 20*1 
Major Noble, R.A. . 26T 
