ME ROYAL ARTILLERY INSTITUTION. 
435 
The second shield which was tested, was constructed on the same principle 
as the first, but, only two layers of planks were used, the planks of the front 
layer (Z>) varying in thickness from 6" to 8", placed on a horizontal layer 
( C ) 5 r/ thick. 
This target was subjected to two days experiment, and a total weight of 
2,148 lbs. of steel and cast-iron projectiles, from some of the heaviest* * * § guns 
which could be got for the purpose, struck the shield at 200 yds. range with 
velocities ranging up to 1460 ft. The reports are decidedly favourable. After 
the first day's trial the Committee reported that “ the result of this experi¬ 
ment is very satisfactory, and Captain Inglis appears to have succeeded in 
producing a shield well adapted for the purpose intended. The fastenings*}* 
in this case stood the test remarkably well and after the final experiment 
the report states :—“ This shield was exposed to a very severe trial, but was in 
very good order at the conclusion of the experiment, and the result proved 
that it is by far the best which has yet been tried for land purposes." The 
total amount of work expended on the target, by the projectiles fired at it, was 
28,579,225 foot pounds, and yet the shield at the conclusion of the second 
day's firing was “in very good order and could easily be made as good as 
ever, the mode adopted in its construction admitting of its being very 
readily repaired4" 
One of the greatest advantages of this plan appears to consist in its 
capability of universal application, for it must be evident that when once the 
struts are in place, any required amount of protection can be given, either at 
the time of the construction of the work or subsequently; for instance, where 
only slight protection is required one layer of planks would be used, at a 
more important point, two layers and so on,—and these planks could be put 
up without the use of any skilled labour. 
A large casemate, which has been built at Shoeburyness, will test the 
merits of two other plans of protection for embrasures, but whatever 
may prove to be their power of resistance, I do not believe that in 
the three points of economy, simplicity, and capability of universal appli¬ 
cation, Captain Inglis's shield has any probability of being distanced. 
The following points are considered to be now well established in regard to 
iron armour :§— 
(1) No material for armour plates yet tested has been found to be equal to 
wrought-iron of the softest quality. 
(2) All irregularities, such as corrugations, projections, bosses, &c., are rather a 
source of weakness than of strength, it having been proved that the best application 
of the material is a plane-surfaced plate of uniform thickness. 
(3) Small and narrow plates are weaker than large and wide ones of the same 
thickness. 
* 10-5" rifled gun, was the heaviest used. 
f This has reference to the report on the 1st shield, in which the Committee state that <c the mode 
of fastening, appeared a source of weakness to the planks.” 
J As hearing on this point it may he stated that during the last day’s trial one of the through 
bolts was broken at the 2nd round, and was easily knocked out and replaced by a new bolt before 
No. 3 round was fired. 
§ Report Special Committee on Iron 1862. 
[VOL. IV.] 
57 
