74 
MINUTES OF PROCEEDINGS OF 
is completely cracked through in two places and a portion on the left side 
between the two cracks appears ready to come away with a blow. It did, 
however, receive a blow from a 10-inch steel shot partly on the separated 
piece after it was cracked through without giving way. 
7. The Committee had intended further fire on both shields, but their 
steel shot are exhausted. 
It is to be observed that the simple rolled iron plate possesses an 
important advantage in having no bolts, nuts, washers, or rivets to cause 
casualties in the work. 
The west shield owes its attachment entirely to a system of bars of 
railway iron built into the granite and held by other similar bars crossing 
them and turned down as cramps. There are 10 of these cramping bars 
above and below, of which 5 are broken. 
This mode of fastening appeared amply secure, and it is perhaps the only 
way in which a thick plate in one mass can be held, but it has the disadvan¬ 
tage as compared with that employed for the other shield, that it forms a 
part of the structure, and there would be no means of replacing a wounded 
shield without extensive pulling clown of the interior. 
8. Considered as an embrasure the opening into which the west shield 
is inserted has the disadvantage of deflecting in shot that strike outside of it. 
The Committee ascertained this by firing five 40-pr. segment shells so aimed 
as to impinge on the granite from each surface, right, left, under, and over. 
In every case some of the splinters or segments entered the casemate by 
the embrasure. 
In one case the quantity that got in was sufficient to have been very 
destructive to the men both in the casemate struck and in the adjoining 
one, the segments having glanced off at an angle of about 45°. 
The marks on the wooden screens were so close and so numerous as to 
make it difficult to count them. 
The east embrasure, which is 12 feet wide, is not liable to these casualties 
and was therefore not put to the same test. 
The Committee do not think any iron shield should be less than 12 feet 
wide when recessed in stone openings of the general character of those they 
have tried. 
9. The centre pier or space between the embrasures received on this 
occasion 19 blows, and had previously received 3,* total 22; viz.:— 
7"-0 
yds. 
foot tons* 
cast-iron shot. . 
. 600 
2 
2994 
8"*0 
ft ••••••••«< 
. 600 
2 
3898 
9"*22 
li .......... 
. 1000 
1 
2666 
9"*22 
steel shot . . 
. 1000 
1 
2666 
9"*22 
it ••*•••••»«•«< 
. 600 
1 
2969 
9 ,, *22 
cast-iron shot. 
. 600 
2 
5938 
9"*22 
steel shell .. . 
. . 600 
1 
2969 
10"-0 
cast-iron shot . 
........ 600 
12 
37,752 
22 ) 61,852 
Average blow.. 
....2811 
* See Report, No. 3765, p. 70; 
