MINUTES OF PEOCEEDINGS OF 
83 
Main object of experiment . 
11. It formed no part of the design of the proposers of the experiment, 
however, to make a comparison (as supposed by the Ordnance Select 
Committee) between a granite structure with iron shields at the embrasures 
and a structure wholly plated with iron. It was known before the experi¬ 
ment was proposed that a granite, or indeed any other structure, could be 
destroyed if fired at leisurely and by sufficiently powerful artillery from a 
land battery for a sufficient length of time. It was of course also known 
that an iron structure could be made stronger than a granite structure, 
if expense were no object. 
The main object of the experiment was to ascertain the power of resistance 
of a granite casemated fort to a sea attack. 
'Effect produced not so great as was anticipated. 
12. The granite outside was, of course, much smashed by the successive 
shots and salvoes fired at it; but in the interior of the casemates, there was 
for a long time no effect produced which would have prevented the guns 
being worked. The result, indeed, showed a much greater stability under 
a close and deliberate fire of modem ordnance than had been expected. 
This is evident on a comparison of the reports of the Ordnance Select 
Committee, dated respectively the 26th May, 1865, and the 12th December, 
1865. 
In the first report, dated 26th May, 1865, the Committee stated that a 
casemate of the description referred to (C would be rendered untenable if 
struck by half a dozen consecutive shots delivered from a gun ofequal power f 
i.e. a 12 ton gun. In the second report, dated 12th December, 1865, the 
Committee state that the casemates " were noted as beginning to be untenable 
after the ( 62>rd hit on the granite , and quite so after the 54-th hit.” 
13. The details of the experiment, which will be found more at length 
in the report of the Ordance Select Committee were as follows - 
The structure experimented upon is shewn in Pigs. 1-4, Plate IV. 
The superficial area of the part fired at was about ,630 square feet; the 
area of the granite fired at was about 520 square feet, and that of the iron 
shields (after deducting the space occupied by the embrasures) about 110 
square feet. 
The guns, projectiles, and charges used in the experiment were as follows:— 
Calibre. 
Weight. 
Charge. 
Weight 
of shot. 
Striking velocity. 
600 yds. 
1000 yds. 
600 yds. 
1000 yds. 
in. 
10-00 
9-22 
8-00 
7-00 
tons. 
12 
12 
6 
6 
cwt. 
2 
2 
19 
19 
lbs. 
67 
56 
60 
72. 
lbs. 
41-3 
39-5 
26-0 
18-0 
lbs. 
36-00 
30-25 
22-00 
lbs. 
280 
220 
150 
115 
ft. 
1273 
1395 
1369 
1370 
ft. 
1209 
1322 
1292 
