ABSTRACT MATHEMATICS, OR PURE. The branch which investigates and demonstrates the properties of magnitude, figure, or quantity, absolutely and generally considered, without restriction to any species in particular; such as arithmetic and geometry.
A-BURTON. The situation of casks when they are stowed in the hold athwart ship, or in a line with the beam.
ABUT. When two timbers or planks are united endways, they are said to _butt_ or _abut_ against each other. (_See_ BUTT.)
ABYME. Places supposed to be the site of constant whirlpools, such as Charybdis, the Maelstrom, and others. It means generally an abyss.
ABYSS. A deep mass of waters; in hydrography it was synonymous with _gulf_.
ACADEMITE. An old term for an officer brought up at the Royal Navy Academy at Portsmouth, afterwards named the Royal Naval College.
ACAIR-PHUILL. Compounded of the British _acair_ or anchor, and _phuill_, a pill, or harbour, and means a safe anchorage.
ACALEPHÆ. A class of marine animals of low organization, having a translucent jelly-like structure, and frequently possessing the property of stinging, whence their name (ἀκαλήφη, a nettle). The common jelly-fish (_Medusa_) and the Portuguese man-of-war (_Physalia_) are the best-known examples.
ACAST. The old word for _lost_ or _cast-away_. In weighing anchor the head-yards are generally braced _acast_, to cause the vessel to cast in the direction. "Does she take _acast_?" is frequently the question of the officer abaft.
ACATER. An old word for purveyor of victuals, whence _caterer_, or superintendent and provider of a mess. Thus in Ben Jonson's "The Devil is an Ass"--
"He is my wardrobe-man, my _acater_, Cook, butler, and steward."
ACATES. Victuals; provisions purchased; delicious food; dainties.
ACATIUM. A word used in Roman naval affairs for a small boat, and also the main-mast of a ship.
ACCELERATION. The increase of velocity in a moving body by the force of gravity. A planet is said to be accelerated when its actual diurnal motion exceeds its mean. In fixed stars the acceleration is the mean time by which they anticipate the sun's diurnal revolution, which is 3′ 56″ nearly.--_Acceleration of the moon_ is the increase of her mean motion, caused by a slow change in the excentricity of the terrestrial orbit, and which has sensibly diminished the length of the moon's revolution since the time of the earliest observations.
