76 
MINUTES OF PROCEEDINGS OF 
Some of these shots were fired in two salvoes, one of 7-in., 9‘22-in., and 
10-0-in. shot. The other of 7-in., 8-in., 9'22-in., and 10‘0-in. shot aimed 
centrally on the same spot. 
The effect of these shocks was to bring down the whole of the arch, 
except so far as supported by the shield, and to shake out the brickwork 
included between two of the granite stones of the vault inside, and a large 
portion of one of the arch stones itself, making an opening through which 
daylight appeared. 
The brick vaulting behind, although much fissured and cracked in many 
directions, remained otherwise entire, but two or three large pieces of granite 
were detached from the wall and thrown into the work. 
The arch stones had been twice struck before the salvoes. 
12. The smaller arch over the west embrasure which differs in structure 
from the other received ten blows, but they were of somewhat higher average 
value; viz. :•— 
" 
yds. 
foot tons. 
7-in. 
0 
0 
8 -in. cast-iron shot . 
. 600 
1 
1,949 
9"*22 „ . 
. 1000 
8 
21,328 
9"‘22 cast-iron shell. 
. 1000 
1 
2,666 
10 ) 25,943 
Average blow .2594 
The effect was to bring down the arch stones and the course of granite 
above them to a depth of five feet; that is to say, to the plane of the shield 
which, however, supported what rested immediately upon it, and to expose 
the concrete of the bomb proof arch. 
The vaulting inside, although much cracked, remained otherwise entire. 
13. The east pier was structurally rather stronger than the west pier, 
but the former having been weakened by the blow of the 10-inch steel shot, 
which split blocks Cl and Dl before glancing on the shield, the Committee 
appropriated the 7-in. gun to its demolition, and took the heavier 8-in. gun 
for the same work on the west pier. The B and C blocks were demolished 
externally by the 7-in. gun in ten rounds with charges due to 600 yards 
range, and the blocks behind them were split, throwing large splinters into 
the work but without entirely giving way, perhaps half of each may remain 
on its bed. 
The last round fired at it was an 8-inch steel shell. It did not per¬ 
ceptibly increase the damage externally but threw a block of three or four 
cwt. to a distance of 20 feet across the casemate inside. 
The aggregate value is 18,338 foot tons, the average force 1528 foot 
tons. 
14. The west pier was struck by four 8-in. shot fired with the 600 yards 
charge before either of' the granite blocks was so far cut away as to make 
an opening into the work. This took place, however, at the fifth shot. 
