_See_ SALVAGE.)

DERIVATION. In artillery, the constant deflection of a rifled
projectile. (_See_ DEFLECTION.)

DERRICK. A single spar, supported by stays and guys, to which a purchase
is attached, used in loading and unloading vessels. Also, a small crane
either inside or outside of a ship.

DERRICK, TO. A cant term for setting out on a small not over-creditable
enterprise. The act is said to be named from a Tyburn executioner.

DERRING-DO. A Spenserian term for deeds of arms.

DESCENDING NODE. _See_ NODES.

DESCENDING SIGNS. Those in which the sun appears to descend from the
north pole, or in which his motion in declination is towards the south.

DESCENDING SQUALL. A fitful gust of wind issuing from clouds which are
formed in the lower parts of the atmosphere. It is usually accompanied
with heavy showers, and the weatherwise observe that the squall is
seldom so violent when it is followed as when it is preceded by rain.
(_See_ WHITE SQUALL as a forerunner.)

DESCENSION. The same as _oblique ascension_ (which see).

DESCENT. The landing of troops for the purpose of invading a country.
The passage down a river.

DESCRIPTION-BOOK. A register in which the age, place of birth, and
personal description of the crew are recorded.

DESERT. An extensive tract, either absolutely sterile, or having no
other vegetation than small patches of grass or shrubs. Many portions of
the present deserts seem to be reclaimable.

DESERTER. One that quits his ship or the service without leave. He is
marked R (_run_) on the books, and any clothes or other effects he may
have left on board are sold by auction at the mast, and the produce
borne to account.

DESERTION. The act of quitting the Army or Navy without leave, with
intention not to return.

DESERTION-MONEY. The sum of three pounds paid to him who apprehends a
deserter, which is charged against the offender's growing pay--his wages
for previous service having become forfeited from his having _run_.

DESTROYING PAPERS. A ground of condemnation in the Admiralty court.

DETACHED. On detached service. A squadron may be detached under a
commodore or senior officer.

DETACHED BASTION. A bastion cut off by a ditch about its gorge from the
body of the place, which latter is thus rendered in a degree independent
of the fall of the former.

DETACHED ESCARP. An escarp wall, originally invented by Carnot, and
revived by the Prussians, removed some distance to the front of the
r