THE ROYAL ARTILLERY INSTITUTION. 
423 
plating, declared that the proper thing was a combined backing of wood and 
iron; and to test this principle two targets, Mr Chalmers' and Mr Clark's 
were constructed and experimented on in 1863. 
The record of these experiments will be found in the “ Proceedings,"* but 
I find from the Beport of the Special Committee on Iron that the Committee 
considered the system of compound backing adopted in the te Chalmers" 
target of considerable advantage in adding strength and resisting power to 
the structure, and that it afforded great support to the armour plates and 
prevented buckling. 
This construction, however, was not considered well adapted for ship 
building, and has therefore not been adopted. Mr Clark's target was very 
complicated in its construction and was not favourably reported on. 
It will be seen from what I have stated, that up to this time three systems 
had been tested : (1) Iron armour plates on wood backing; (2) Structures 
wholly of iron; (3) Iron armour plates on a combined backing of wood and 
iron, and of these three, speaking only of their merits in resistance to pro¬ 
jectiles, Class No. 3 are decidedly the best. 
With this digression we may now pass on to a consideration of the 
“ Bellerophon.” 
Until the introduction of very heavy guns and steel projectiles, the 
protection afforded by the “ Warrior" was amply sufficient, but in order 
to enable defence to keep pace with attack it has becomepecessary largely 
to increase the thickness of armour. This necessity has led to the area of 
protection being reduced, and thus ships are now being constructed (the 
“ Bellerophon," “ Hercules," &c.) with square boxes, or turrets, and a belt 
of iron to protect the water line. 
The “ Bellerophon " is an iron ship of 4,246 tons and 1000 horsepower, 
and is being constructed to carry 14 guns. 
Her length is 300 feet, and her battery is about 90 feet in length; her 
armour extends all round the ship, as high as the main deck, and is carried 
up to the upper deck on the bow and the central battery; her draught of 
water is 21 ft. forward and 26 ft, aft. 
The “ Bellerophon" target was constructed to * b c d 
represent a portion of the side of the “Bellero¬ 
phon" iron-cased frigate. 
The construction is as follows •— 
Bibs (A), 2 feet apart, made of an angle-iron 
10" x 3^" x and two angle-irons 3|" x 3J" x f" 
riveted together; to the double angle-irons of this 
frame the skin ( B ), composed of two thicknesses 
of J" plating, was riveted with a layer of painted 
canvas interposed. On the outside of the skin, 
horizontal angle-iron stringers, ( C "), are attached, 
and the wood backing ( C ), 10" thick, is worked 
longitudinally on the skin plating between the 
angle-iron stringers and is bolted with nut and 
screw bolts through the skin plating. The armour 
consists of wrought-iron rolled plates (L) 6" thick, 
secured with bolts 2J" and 2f" diameter. 
* Vide Yol. III. p. 316. 
