now manufactured in England, Malta, and the United States.

NANT. A brook, or small river, on the coasts of Wales.

NAPHTHA. A very inflammable, fiercely burning fluid, which oozes from
the ground or rock in many different localities, and may be obtained by
the distillation of coal, cannel, and other substances. It is nearly
related to _petroleum_ (which see), and is used for lighting,
combustible, and various other purposes.

NAPIER'S BONES. Small rods, arranged by Lord Napier to expedite
arithmetical calculations. In _Hudibras_:

"A moon-dial, with Napier's bones,
And several constellation stones."

NARKE. A ray of very wonderful electric powers.

NARROWING OF THE FLOOR-SWEEP. For this peculiar curve, _see_ HALF-BREADTH
OF THE RISING.

NARROWS. The most confined part of a channel between two lands, or any
contracted part of a navigable river.

NARWHAL. The _Monodon monoceros_, an animal of the cetacean order, found
in the Arctic seas, and distinguished by the single long pointed tusk
projecting straight forward from its upper jaw, whence it is also termed
sea-unicorn.

NATURAL FORTIFICATION. Those obstacles, in the form or nature of the
country, which impede the approaches of an enemy.

NATURAL MOTION. A term applied to the descending parabolic curve of a
shot or shell in falling.

NAUFRAGIATE, TO. An old expression, meaning to suffer shipwreck. It
occurs in Lithgow's _Pilgrime's Farewell_, 1618.

NAULAGE. A freight or fare.

NAUMACHIA. An artificial piece of water whereon the ancient Romans
represented a sea-fight, supposed to have originated in the first Punic
war.

NAUROPOMETER. An instrument for measuring the amount of a ship's heel or
inclination at sea.

NAUSCOPY. The tact of discovering ships or land at considerable
distances.

NAUTICAL. Relating to navigation, sailors, or maritime affairs in
general.

NAUTICAL ALMANAC. A book of the first necessity to navigators. (_See_
EPHEMERIS.)

NAUTICAL ASSESSORS. Persons of nautical experience appointed to assist
the judge of the admiralty and other courts in technical difficulties.

NAUTICAL ASTRONOMY. That part of the celestial science which treats of
the planets and stars so far as relates to the purposes of navigation.

NAUTICAL DAY. This day commences at noon, twelve hours before the civil
day, and ends at noon of the day following. (_See_ DAY.)

NAUTICAL MILE (MEAN) = 6075.6 feet.

NAUTICAL STARS. About 72 of the brightest, wh