l, this sort of fire has been of little efficacy; but by
the aid of a simple implement, readily made on board ship, it is
believed that good results may be obtained, and particularly at night,
when firing from guns on covered decks is now absolutely ineffective.

It consists of a simple metal or wooden batten, sliding in two beckets
attached to the outer or inner sides of each of the brackets of the
carriage, retained in any position by a thumb-screw. This batten is
graduated by experiment or calculation for either the parallel or
converging fire, for such points on the bow, beam, or quarter, as may
be deemed advisable.

A small knob is screwed into the inner end of each batten, and a
cod-line provided, with a loop in each end, somewhat longer than the
width across the transom. If, then, one of the battens be drawn out to
the graduation representing the degree of train required, the line
stretched taut from the two knobs and hitched, and guns trained until
this line is parallel to a mark on the deck, or one of the seams of
the deck-plank--if they are parallel to the keel--the guns will all
make the required angle, and may be fired simultaneously or in
succession, as ordered.

[Illustration]

321. The principal object in view, therefore, is so to prepare the
training by anticipation, that when the smoke rises, or on sheering
the vessel, the enemy shall be visible to all the Gun Captains at the
same time; giving them the choice to fire at will, or on a given
signal, if simultaneous fire be desired.

It diminishes the great disadvantages of guns on covered decks, where
the Gun Captains can only with difficulty ascertain the direction of
the enemy; and places the whole battery more completely under the
control of the Commander.

322. The principal care of the Commander must be to keep his guns
always bearing on the enemy, and never pass the limits of extreme
train for all his guns, unless absolutely necessary in manoeuvring.

This he must regulate, either by one of the guns in his vicinity, or,
better, by the aid of a bearing-plate, a species of plane-table which
gives the angular bearing of the object.

323. Concentration of fire upon a particular part of an enemy's vessel
may also be obtained by a general order for the guns to be aimed to
strike that part when visible, leaving the Captains of guns to
determine the proper time for firing, according to circumstances at
the moment. This obviates the objections due