50 
MINUTES OF PEOCEEDINGS OF 
After this the 300-pr. Armstrong shunt gun fired a spherical wrought- 
iron solid shot, weighing 163 lbs., with a charge of 45 lbs., which, at 30 
yards in front of the target, gave a velocity of 1630 ft. per second. It struck 
the 7|-in. plate where it had no teak backing, and made an indent 3|in. 
deep, and 13 inches in diameter, with a crack on the face of the indent; 
the plate was considerably' bulged in, and at the back it showed a large 
starred crack. The shot was flattened out to a diameter of 13 in. 
The material of which these armour plates was made proved itself to be 
of uniform and excellent quality. 
The practical lessons to be learnt from this day*s experiments seem to be 
these:— 
1st. That guns are already in existence which can completely penetrate 
with shot the best 7 4-in. armour that can be made, and which can, with 
shell, pierce the sides of a ship built, as to frame, much more strongly than 
our best ship, and protected with our best 5J-in. armour. 
2nd. That iron plates can now, with the improved manufacture of the 
country and the energy brought out by the occasion, be made of dimensions 
hitherto quite unattainable, and yet without losing anything in quality. 
Chalmers 9 target . April 27, 1863. 
The next experiment of any importance was made at Shoeburyness to test 
the merits of a principle of construction proposed by Mr Chalmers for iron¬ 
clad ships of war. 
The chief features of the system, advocated by this gentleman (and with 
such confidence that he made the target to test its value at his own expense, 
a tiling not thought of in recent times by any other inventor), may be thus 
described:— 
The ribs and skin constituting the frame of the ship are very similar to 
those of the “ Warrior,” and the difference consequently lies in the external 
protection; this, instead of being obtained by armour in one thickness with 
a simple backing of teak, as in all the ships yet building or afloat, is 
composed as follows : first, he presents to the shot an armour plate 3f in. 
thick, of hammered iron, which is backed by a compound mass of iron and 
teak 10 in. thick; this backing is made up of alternate timbers 10 in. by 
5 in., and wrought-iron ribs 10 in. by T T g in., laid horizontally, and bolted 
together at frequent intervals by vertical screw bolts of 1 in. diameter. 
This compound backing is supported in rear by, and attached to, a plate 
1| inch in thickness, this being called an intermediate or second armour 
plate; and the intermediate armour is again backed by a thickness of 5 in. 
of teak to form a cushion, behind w r hich come the skin and ribs before 
described as being similar to the “ Warrior’s.” The armour is held on by 
2j-in. screw bolts formed with a peculiarly shaped stepped head, instead of 
the usual conical form, and nutted at the back of the skin. 
Thus the side consists, exclusive of skin and ribs, of 5 in. of armour and 
15 in. of backing (10 in. of which is a compound of iron and teak), against 
