THE EOYAL ARTILLERY INSTITUTION 
29 
REMARKS ON IRON DEFENCES. 
Bx CAPTAIN H. C. S. DYER, E.A. 
The first experiment recorded was carried on at Woolwich in 1827, at 
the instance of General Ford, E.E., who proposed to protect masonry with 
wrought-iron bars.* To test the value of this proposal, a block of Dundee 
stone 6x5x2 feet was covered with lj-inch wrought-iron bars in horizontal 
courses, these were covered with another layer of 1^-inch bars placed vertically. 
The target was fired at with 24-pr. solid cast-iron shot, at a range of 
634 yds.: after 20 rounds had struck, 19 of the front bars and 5 of the hori¬ 
zontal course were broken, 4 bars were detached. The result of this experi¬ 
ment was considered so unsatisfactory that all idea of using iron as a means 
of defence was for the time abandoned; it was again revived about the year 
1850, by Lord Boss and others, but apparently the time had not yet arrived 
for these sweeping changes in old established notions, and it was reserved 
for the Emperor Napoleon III. to bring the question to a practical issue. 
The superiority of the French floating battery engaged at Kinburn in 
1855, over the wooden ships engaged at the same time was so indisputably 
proved, that the Admiralty determined on providing themselves with some 
vessels of this class ; two of them reached the Baltic a short time before 
peace was declared, and were not required. As these vessels owing to the 
great weight of their armour, and being provided with engines of such small 
power, could only be made available for coast defences, it was determined to 
construct others which should be invulnerable, without sacrificing the im¬ 
portant element of speed. Before proceeding in the construction of these 
ships, it was considered advisable to determine by experiment the best mode 
of disposing the armour for defence. For this purpose a committee was 
formed in July 1859, and carried on experiments on various descriptions of 
iron until April 1860, when the question was handed over to the Ordnance 
* “A wall 5 ft. high and 7 ft. thick, built of the best Aberdeen granite blocks, cased with two layers 
of iron bars, the under layer being horizontal of 1-inch square, and the outer vertical If-inch square, 
and each layer being strongly cramped into the granite, and the wall covered and surrounded by 
12 ft. of earth. Cost £4 16s. 8 d. 
“ The stone, iron, and convict labour for this work were given gratis by order of the Board, and 
the expense of coals and lime only charged, it being intended to try an idea of General Ford’s, that 
wrought-iron bars would resist and break cast-iron shot. 
“ The experiment was made from a 24-pr. at 600 yds. distance, which, on striking the face of the 
iron-cased wall only nineteen times, had penetrated through both layers of bars, and pulverized the 
stone under them, so completely as to render further battering unnecessary.”—Extracts from Books 
in the Royal Engineer Office, Woolwich. “ Iron-cased Wall, Royal Arsenal, erected agreeably to 
Board’s Orders of 12th April and 19th May, 1826, by convict labour.” 
