AT ANCHOR. The situation of a vessel riding in a road or port by her anchor.
ATAR. A perfume of commerce, well known as atar-of-roses; atar being the Arabic word for fragrance, corrupted into _otto_.
A'TAUNTO, OR ALL-A-TAUNT-O. Every mast an-end and fully rigged.
ATEGAR. The old English hand-dart, named from the Saxon _aeton_, to fling, and _gar_, a weapon.
ATHERINE. A silvery fish used in the manufacture of artificial pearls; it is 4 or 5 inches long, inhabits various seas, but is taken in great numbers in the Mediterranean. It is also called _argentine_.
ATHILLEDA. The rule and sights of an astrolabe.
ATHWART. The transverse direction; anything extending or across the line of a ship's course.--_Athwart hawse_, a vessel, boat, or floating lumber accidentally drifted across the stem of a ship, the transverse position of the drift being understood.--_Athwart the fore-foot_, just before the stem; ships fire a shot in this direction to arrest a stranger, and make her bring-to.--_Athwart ships_, in the direction of the beam; from side to side: in opposition to _fore-and-aft_.
ATLANTIC. The sea which separates Europe and Africa from the Americas, so named from the elevated range called the Atlas Mountains in Morocco.
ATLANTIDES. The daughters of Atlas; a name of the Pleiades.
ATLAS. A large book of maps or charts; so called from the character of that name in ancient mythology, son of Uranus, and represented as bearing the world on his back. Also the Indian satin of commerce.
ATMOSPHERE. The ambient air, or thin elastic fluid which surrounds the globe, and gradually diminishing in gravity rises to an unknown height, yet by gravitation partakes of all its motions.
ATMOSPHERIC OR SINGLE-ACTION STEAM-ENGINE. A condensing machine, in which the downward stroke of the piston is performed by the pressure of the atmosphere acting against a vacuum.
ATMOSPHERICAL TIDES. The motions generated by the joint influence of the sun and moon; and by the rotatory and orbital course of the earth,--as developed in trade-winds, equinoctial gales, &c.
ATOLLS. An Indian name for those singular coral formations known as lagoon-islands, such as the Maldive cluster, those in the Pacific, and in other parts within the tropics, where the apparently insignificant reef-building zoophytes reside.