survey it accurately, and, if possible, to
improve the construction or equipment of the vessels, if they appeared
defective, either for the purpose of sailing or fighting. It seemed to him,
on examining them, that they could not be easily and quickly worked during
an engagement, being much heavier and more unwieldy than those of the
Carthaginians. As this defect could not be removed, he tried whether it
could not be compensated; and an engineer in the fleet succeeded in this
important object, by inventing that machine which was afterwards called
_corvus_.

The immediate purpose which this machine was to serve is clearly explained
by all the ancient authors who mention it: its use was to stop the enemy's
ships as soon as the Roman vessels came up with them, and thus to give them
an opportunity of boarding them; but the construction and mode of operation
of these machines it is not easy to ascertain from the descriptions of
ancient authors. Polybius gives the following description of them: "They
erected on the prow of their vessels a round piece of timber, about one
foot and a half in diameter, and about twelve feet long, on the top of
which a block or pully was fastened. Round this piece of timber a stage or
platform was constructed, four feet broad, and about eighteen feet long,
which was strongly fastened with iron. The entrance was lengthways, and it
could be moved about the piece of timber, first described, as on a spindle,
and could be hoisted within six feet of the top. Round this there was a
parapet, knee high, which was defended with upright bars of iron, sharpened
at the end. Towards the top there was a ring, through which a rope was
fastened, by means of which they could raise and lower the engine at
pleasure. With this machine they attacked the enemy's vessels, sometimes on
their bow, and sometimes on their broadside. When they had grappled the
enemy with these iron spikes, if the ships happened to swing broadside to
broadside, then the Romans boarded them from all parts; but when they were
obliged to grapple them on the bow, they entered two and two, by the help
of this engine, the foremost defending the forepart, and those who followed
the flanks, keeping the boss of their bucklers level with the top of the
parapet."

From this description of the corvus, it is evident that it had two distinct
uses to serve: in the first place, to lay hold of and entangle the enemy's
ships; and, secondly, after it had accomp