of rocks.--_To make a flash_, is
to let boats down through a lock; to flash loose powder at night to show
position.

FLASHING-BOARD. To raise or set off.

FLASHING-SIGNALS. By Captain Colomb's plan, the lime light being used on
shore, and a plain white light at sea, is capable of transmitting
messages by the relative positions of long and short dashes of light by
night, and of collapsing cones by day.

FLASH IN THE PAN. An expressive metaphor, borrowed from the false fire
of a musket, meaning to fail of success after presumption.

FLASH RIM. In carronades, a cup-shaped enlargement of the bore at the
muzzle, which facilitates the loading, and protects the ports or rigging
of the vessel from the flash of explosion.

FLASH VESSELS. All paint outside, and no order within.

FLASK. A horn or other implement for carrying priming-powder. Smaller
ones for fire-arms are usually furnished with a measure of the charge
for the piece on the top.

FLAT. In ship-building, a straight part in a curve. In hydrography, a
shallow over which the tide flows, and over the whole extent of which
there is little or no variation of soundings. If less than three
fathoms, it is called _shoal_ or _shallow_.

FLAT-ABACK. When all the sails are blown with their after-surface
against the mast, so as to give stern-way.

FLAT-AFT. The sheets of fore-and-aft sails may be hauled flat-aft, as
the jib-sheet to pay her head off, the driver or trysail sheets to bring
her head to the wind; hence, "flatten in the head-sheets."

FLAT-BOTTOMED. When a vessel's lower frame has but little upward
inclination.

FLAT CALM. When there is no perceptible wind at sea.

FLAT-FISH. The _Pleuronectidae_, a family of fishes containing the soles,
flounders, turbots, &c., remarkable for having the body greatly
compressed laterally; they habitually lie on one side, which is white,
the uppermost being coloured, and having both the eyes placed on it.

FLAT-NAILS. Small sharp-pointed nails with flat thin heads, longer than
tacks, for nailing the scarphs of moulds and the like.

FLATS. All the floor-timbers that have no bevellings in midships, or
pertaining to the _dead-flat_ (which see). Also, lighters used in river
navigation, and very flat-floored boats for landing troops.

FLAT SEAM. The two edges or selvedges of canvas laid over each other and
sewed down.

FLAT SEIZING. This is passed on a rope, the same as a round seizing, but
it has no riding turns.

FLATT