THE ROYAL ARTILLERY INSTITUTION. 
37 
RECENT GUNNERY EXPERIMENTS UPON IRON ARMOUR, 
BY CAPTAIN INGLIS, R.E. 
[Extracted, with the consent of the Editor, from Yol. XII. of R.E. Corps Papers; and with the 
permission of the Author]. 
In last year's volume of these Papers,* when treating the subject of the 
application of iron to defensive works, I gave a brief account of most of 
the experiments which had been made, up to June, 1862, upon iron armour. 
I propose now to give an outline of the principal experiments made since 
that time, with a few remarks upon their results. 
Minotaur Target . July 7, 1862. 
This experiment was made at Shoeburyness to test the merits of the 
construction adopted in the “ Minotaur/' and her class of iron clad steam 
frigates. 
In these ships the armour is 5J in. thick, instead of 4f in. as in the 
“ Warrior," but the thickness of the teak backing is reduced from 18 in. to 
9 in.—9 in. of teak being very nearly equivalent in weight to 1 in. of 
■wrought-iron. The skin and ribs are the same as in the “Warrior." 
The target now used was therefore constructed on these principles, and 
presented a front of three armour plates : one made by Messrs Brown, of 
Sheffield, measured 12 ft. 6 in. by 3 ft. 4 in.; another, made at the Thames 
Iron Works, measured 9 ft. by 3 ft. 7 in.; and the third, made by Messrs 
Beale, measured the same as the first named. 
Each plate was secured by three rows of bolts, the upper and lower rows 
being If in. diameter, and the middle row If in. diameter; all but a few of 
the bolts round the port passed through the teak and skin. 
The proportion of bolt to surface of the ship's side was as one bolt to 
about 31 ft. superficial; and the aggregate sectional area of bolt to a given 
area of surface was rather greater than in the “Warrior." 
There were junction pieces. If in. thick, at the back of all the joints of the 
plates. 
The guns used against this target were the 12 ton Armstrong muzzle¬ 
loading gun, throwing spherical 150 lb. cast-iron and 162 lb. wrought-iron 
shot, with 50 lb. charges of powder, the former having an initial velocity of 
1750 ft., and the latter of about 1700 ft. per second; and a service 68-pr. 
throwing 67 lb. cast and 711b. wrought-iron shot with 16 lbs. of powder— 
the cast shot having an initial velocity of 1580 ft., the wrought-iron about 
1530 ft. per second; all at 200 yds. range. 
The first 1501b. cast shot struck the Thames Iron Company's plate and 
made a hole about a foot square through the armour and bedded itself deep 
* Yide R.E. Corps Papers, Yol. XI. p. 184 
