and yet kept
secret is indeed a wonder, and we must therefore conjecture that the
marquis had some other device in his mind. Certain it is, that the idea
of converting vessels into traps of destruction, or of so defending them
as to destroy assailants after boarding the decks, has not been very
extensively developed.

'No. XVI.--How to make a sea castle or a fortification _cannon
proof_, capable of a thousand men, yet sailable at pleasure to
defend a passage, or in an hour's time to divide itself into three
ships, as fit and trimmed to sail as before; and even whilst it is
a fort or castle, they shall be unanimously steered, and
effectually be driven by an indifferent strong wind.'

It is to be regretted that Parliamentary or other inducements were not
employed to obtain from the marquis, at least the publication of his
views as regards making vessels cannon proof. From the general character
of his inventions, and from comparison of them, it appears he had full
faith in cannon-proof floating batteries as a means of defence, and, we
may consequently and justly infer, as superior to the latter. Among his
inventions there are but two in reference to 'fortifications,' and both
of these are after a manner a transfer of the floating battery to land,
or an application of the principle of mobile defences. These are as
follows:

'No. XXIX.--A portable fortification, able to contain five hundred
fighting men, and yet, in six hours' time, may be set up and made
cannon proof, upon the side of a river or pass, with cannon mounted
upon it, and as complete as a regular fortification, with halfmoons
and counterscarps.

'No. XXX.--A way in one night's time to raise a bulwark, twenty or
thirty foot high, cannon proof, and cannon mounted upon it; with
men to overlook, command, and batter a town, for though it (the
bulwark) contain but four pieces, they shall be able to discharge
two hundred bullets each hour.'

There can be but little question, from all I have cited, that the
Marquis of Worcester was singularly in advance of his age as regarded
the great principles of warfare. We have found him thus far, in all
probability, acquainted with the construction of permutable seals, and
indeed of the grand principle of permutation applied to technology in
several respects (vide "Century" Nos. III, IV, V,) of the telegraph, of
sinking vessels by torpedoes, and,