AZIMUTH. A word borrowed from the Arabic. The complement of the amplitude, or an arc between the meridian of a place and any given vertical line.
AZIMUTHAL ERROR. See Meridian Error.
AZIMUTH CIRCLES. See Vertical Circles.
AZIMUTH COMPASS. A superior graduated compass for ascertaining the amount of magnetic variation, by amplitude or azimuth, when the sun is from 8° to 15° high, either after its rising or before its setting. (See Magnetic Azimuth.) It is fitted with vertical sight vanes for the purpose of observing objects elevated above the horizon.
AZOGUE. [Sp.] Quicksilver.
AZOGUES. Spanish ships fitted expressly for carrying quicksilver.
AZUMBRE. A Spanish wine-measure, eight of which make an arroba.
AZURE. The deep blue colour of the sky, when perfectly cloudless.
B.
BAARD. A mediæval transport.
BAARE-Y-LANE. The Manx or Gaelic term for high-water.
BAAS. An old term for the skipper of a Dutch trader.
BAB. The Arabic for mouth or gate; especially used by seamen for the entrance of the Red Sea, Bab-el-mandeb.
BABBING. An east-country method of catching crabs, by enticing them to the surface of the water with baited lines, and then taking them with a landing net.
BABBLING. The sound made by shallow rivers flowing over stony beds.
BAC. A large flat-bottomed French ferry-boat. In local names it denotes a ferry or place of boating.
BACALLAO [Sp.] A name given to Newfoundland and its adjacent islands, whence the epithet is also applied to the cod-fish salted there.
BACCHI. Two ancient warlike machines; the one resembled a battering-ram, the other cast out fire.
BACK. To back an anchor. To carry a small anchor ahead of the one by which the ship rides, to partake of the strain, and check the latter from coming home.—To back a ship at anchor. For this purpose the mizen top-sail is generally used; a hawser should be kept ready to wind her, and if the wind falls she must be hove apeak.—To back and fill. To get to windward in very narrow channels, by a series of smart alternate boards and backing, with weather tides.—To back a sail. To brace its yard so that the wind may blow directly on the front of the sail, and thus retard the ship's course. A sailing vessel is backed by means of the sails, a steamer by reversing the paddles or screw-propeller.—To back astern. To impel the water with the oars contrary to the usual mode, or towards the head of the boat, so that she shall recede.—To back the larboard or starboard oars. To back with the right or left oars only, so as to round suddenly.—To back out. (See Back a Sail.) The term is also familiarly used for retreating out of a difficulty.—To back a rope or chain, is to put on a preventer when it is thought likely to break from age or extra strain.—To back water. To impel a boat astern, so as to recede in a direction opposite to the former course.—Backing the worming. The act of passing small yarn in the holidays, or crevices left between the worming and edges of the rope, to prevent the admission of wet, or to render all parts of equal diameter, so that the service may be smooth.—Wind backing. The wind is said to back when it changes contrary to its usual circuit. In the northern hemisphere on the polar side of the trades, the wind usually changes from east, by the south, to west, and so on to north. In the same latitudes in the southern hemisphere the reverse usually takes place. When it backs, it is generally supposed to be a sign of a freshening breeze.
BACK. The outside or convex part of compass-timber. Also a wharf.
BACK, of a Ship. The keel and kelson are figuratively thus termed.
BACK, of the Post. An additional timber bolted to the after-part of the stern-post, and forming its after-face.
BACK-BOARD. A board across the stern sheets of a boat to support the back of passengers; and also to form the box in which the coxswain sits.
BACK-CUTTING. When the water-level is such that the excavation of a canal, or other channel, does not furnish earth enough for its own banks, recourse is had to back-cutting, or the nearest earth behind the base of the banks.
BACK-FRAME. A vertical wheel for turning the three whirlers of a small rope-machine.
BACK-HER. The order, in steam-navigation, directing the engineer to reverse the movement of the cranks and urge the vessel astern.
BACKING. The timber behind the armour-plates of a ship.
BACK-O'-BEYOND. Said of an unknown distance.
BACK OFF ALL. The order when the harpooner has thrown his harpoon into the whale. Also, to back off a sudden danger.
BACK-ROPE. The rope-pendant, or small chain for staying the dolphin-striker. Also a piece long enough to reach from the cat-block to the stem, and up to the forecastle, to haul the cat-block forward to hook the ring of the anchor—similarly also for hooking the fish-tackle. (See Gaub-line.)
BACKS. The outermost boards of a sawn tree.
BACK-STAFF. A name formerly given to a peculiar sea-quadrant, because the back of the observer was turned towards the sun at the time of observing its zenith distance. The inventor was Captain Davis, the Welsh navigator, about 1590. It consists of a graduated arc of 30° united to a centre by two radii, with a second arc of smaller radius, but measuring 6° on the side of it. To the first arc a vane is attached for sight—to the second one for shade—and at the vertex the horizontal vane has a slit in it.
BACKSTAY-PLATES. Used to support the backstays.
BACKSTAYS. Long ropes extending from all mast-heads above a lower-mast to both sides of the ship or chain-wales; they are extended and set up with dead eyes and laniards to the backstay-plates. Their use is to second the shrouds in supporting the mast when strained by a weight of sail in a fresh wind. They are usually distinguished into breast and after backstays; the first being intended to sustain the mast when the ship sails upon a wind; or, in other terms, when the wind acts upon a ship obliquely from forwards; the second is to enable her to carry sail when the wind is abaft the beam; a third, or shifting backstay, is temporary, and used where great strain is demanded when chasing, chased, or carrying on a heavy pressure of canvas: they are fitted either with lashing eyes, or hook and thimble with selvagee strop, so as to be instantly removed.
BACKSTAY-STOOLS. Detached small channels, or chain-wales, fixed abaft the principal ones. They are introduced in preference to extending the length of the channels.
BACKSTERS. Flat pieces of wood or cork, strapped on the feet in order to walk over loose beach.
BACK-STRAPPED. As a ship carried round to the back of Gibraltar by a counter-current and eddies of wind, the strong currents detaining her there.
BACK-SWEEP. That which forms the hollow of the top-timber of a frame.
BACK-WATER.
