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.