414 
ARTILLERY IN COAST DEFENCE. 
stand the bearing of this. In the case of iron armour, the shot 
penetrating, though it only damages the plate at the point of impact, 
will probably do serious damage to whatever is behind the plate ; 
whilst with hard armour no such damage will be done, but the plate 
will be less able to resist a subsequent blow. 
It should be remarked that a shot which only just gets through 
the armour may not affect much damage, since its energy will have 
been almost entirely destroyed, and it may still have to pass (probably 
if a Palliser shot in a broken condition) through obstructions, such as 
coal-bunkers, bulkheads, &c., before reaching a vital part of the ship. 
Horizontal armour may be attacked by direct fire provided the angle 
of descent is over 10 degrees and the striking velocity sufficient; the 
penetration at this angle being about one-fourth of that obtainable 
with an equal velocity by a direct hit on vertical armour. The angle 
of descent depends on the range and on the height of the gun above 
the object; tables, an example of which is given in the Tactical 
Manual, must be worked out in each fort, according to its height above 
the water. It must be remembered that the armoured deck is usually 
about at the level of the water, and that there are generally one or 
more decks above this, so that the shot will have to pass through 
obstructions, losing some of its force before it reaches the armoured 
deck. 
Common shell can be used against thin wrought-iron armour the 
perforation being equal to half the diameter for each 1000 f.s. velocity 
but the backing would greatly impede the further course of the frag¬ 
ments : in this case the shell should be plugged. 1 2 
As regards the attack of armoured decks by high-angle fire, the same 
rules for finding the penetration apply as in other cases. Steel shot 
are the best projectiles for this purpose, as they are less liable to break 
up when striking an object not truly point first, than are Palliser shot. 
Shot would, of course, be very liable to be deflected by upper works 
of the vessel before reaching the armoured deck, and so may strike in 
any position. 
The attack of unarmoured ships, or unarmoured portions of armoured 
vessels, would be carried out with common shell when it is desired 
principally to inflict damage on the vessel and its armament; and by 
shrapnel when it is desired to cause losses among the crew. Common 
shell plugged have been found to explode when passing through thin 
armour or the sides of unarmoured iron ships, and Capt. Nash, R.A., 
has therefore proposed to use them with plugs in preference to fuzes, 
but, as has been pointed out by Capt. May, P.N., the time taken for a 
fuze to act and for the shell to burst will be long enough to allow it to 
penetrate unarmoured sides, while there are many objects on deck— 
funnels/spars, &c.—which, while offering sufficient resistance to set in 
action the fuze, would probably not explode a plugged shell. It would 
1 Captain Orde Browne. Yol. XIV., p. 131. It is not quite clear whether this measure of the 
power to penetrate is intended or not ; Text-Book of G-unnery gives “ half the diameter at short 
ranges.” 
2 The resistance offered by armour, approaching the thickness which the shell can penetrate, 
would check its velocity so much that a fuze would act before penetration was complete; in the 
case of unarmoured sides, the resistance would not be sufficient to cause this check. 
