lEON SHIELDS FOR FORTS. 
367 
marble, or killed outright by a sbeared-off bolt-nut. Men and 
material are alike too costly to be sacrificed, made food for 
powder, as in days of yore. We cannot now replace such loss. 
Moreover, in these iron defences there is so slight a margin, 
that there is practically no medium between perfect security, 
on the one hand, and that worse than utter uselessness which 
transforms a comparatively harmless flying shot — that merely 
hits or misses a solitary mark, or at most knocks over a few 
isolated men — into a wide-spread shower of fragments, hailing 
destruction to life, limb, and material within the limit of a hun- 
dred yards around. The chief considerations to be regarded in 
this frame, beyond it§ duty of securing the armour and holding 
it up to its work, are the fastening it securely in position, so 
that it shall not be driven back, moved laterally, or toppled 
over by the blows of the shot. It is also requisite to provide a 
slight amount of head cover to protect the guns and defenders 
against missiles falling from high trajectories, and to prevent the 
knocking away of the top edge of the shield by direct fire from 
the attacking batteries. The sole-plate should have, too, a ledge 
extending beyond the face of the shield, to grip the armour and' 
prevent its buckling. A rim of this nature all round would 
have a good elfect. 
We now come to the main defence, the armour-plating. Tlie 
very thick solid plates are up to this time, through imperfections 
of manufacture, and unsatisfactory and rude experiments, open 
to the serious objection of being liable to split across. A plate 
so split might fall asunder, or its two halves might be driven in 
bodily by the succeeding fire of the guns ; in short, a split plate 
would no longer be a serviceable defence. It is, however, only 
just to admit that the solid plates have not in any Grovernment 
experiment we have seen been as properly supported and set up 
as they would have been in a permanent fortification ; and both 
in respect to the Brown’s plate ” and the “ Thames plate ” — 
the latest efforts at 15-inch plates — the rough manner in which 
they were set up helped materially the rapid consummation of 
their disrupture. Nevertheless, the iron in both cases did not 
come up in its working to the quality of the best 5-, 6-, and 8- 
inch plates ; and when we reflect upon the vast masses to be 
properly heated to welding heat, the increased number of pro- 
cesses to be gone through, the enormous weights to be lifted 
and moved about in a limited time, and the variety of accidents 
which can happen to an armour-plate in the operations of the 
furnace, the rolling-mill, or the forge, all multiplied in liability 
as the thickness and weight of the plate increases, and, finally, 
that the machinery has not been specially constructed for such 
grand labours, we should not be surprised at deficiencies, but 
ought rather to leniently judge, by inference from what is done, 
