exclusively in
large vessels concentrates coast-defences upon a few points, while, if
it is devoted to a greater number, consisting partly of small vessels,
the line of defences is made more continuous and complete.

_System of Protection_. But the effectiveness of war-vessels need not
depend solely upon their size. First, twice or thrice the power may
be obtained, with the same weight of boilers and machinery, and with
considerable economy, by carrying very much higher steam, employing
simple surface-condensers, and maintaining a high rate of combustion and
vaporization, in accordance with the best commercial-marine practice.
Second, _the battery may be reduced in extent_, and the armor thus
increased rather than diminished in thickness, with a given buoyancy. At
the same time, _the fewer guns may be made available in all directions
and more rapidly worked_, so that, on the whole, a small ship thus
improved will be a match in every respect for a large ship as ordinarily
constructed. Working the guns in small revolving turrets, as by
Ericsson's or by Coles's plan, and loading and cooling them by
steam-power, and taking up their recoil by springs in a short space,
as by Stevens's plan, are improvements in this direction. The plan of
elevating a gun above a shot-proof deck at the moment of aiming and
firing, and dropping it for loading or protection by means of hydraulic
cylinders, and the plan of placing a gun upon the top of the armor-clad
portion of the ship, covering it with a shot-proof hood, and loading it
from below, and the plan of a rotating battery, in which one gun is in a
position to fire while the others attached to the same revolving frame
are loading,--all these obviously feasible plans have the advantages of
avoiding port-holes in the inhabited and vital parts of the vessel, of
rendering the possible bursting of a gun comparatively harmless to the
crew and ship, and of rapid manoeuvring, as compared with the turret
system, besides all the advantages of the turret as compared with the
casemate or old-fashioned broadside system. The necessity of fighting
at close quarters has been remarked. At close quarters, musket-balls,
grape, and shells can be accurately thrown into ordinary port-holes,
which removes the necessity of smashing any other holes in the armor.

Protection at, and extending several feet below the water-line, is
obviously indispensable around the battery of a vessel. It is valuable
at other po