The Sailor's Word-Book
Chapter 13 : ARBOR. In chronometry, a shaft, spindle, or axis.ARBY. A northern name for the thrift o

ARBOR. In chronometry, a shaft, spindle, or axis.

ARBY. A northern name for the thrift or sea-lavender.

ARC, OR ARCH. The segment of a circle or any curved line, by which all angles are measured.

ARC DIURNAL. _See_ DIURNAL ARC.

ARC NOCTURNAL. _See_ NOCTURNAL ARC.

ARC OF DIRECTION OR PROGRESSION. The arc which a planet appears to describe when its motion is direct or progressive in the order of the signs.

ARC OF VISION. The sun's depth below the horizon when the planets and stars begin to appear.

ARCH-BOARD. The part of the stern over the counter, immediately under the knuckles of the stern-timbers.

ARCH OF THE COVE. An elliptical moulding sprung over the cove of a s.h.i.+p, at the lower part of the taffrail.

ARCHED SQUALL. A violent gust of wind, usually distinguished by the arched form of the clouds near the horizon, whence they rise rapidly towards the zenith, leaving the sky visible through it.

ARCHEL, ARCHIL, ORCHILL. _Rocella tinctorum fucus_, a lichen found on the rocks of the Canary and Cape de Verde groups; it yields a rich purple. Litmus, largely used in chemistry, is derived from it.

ARCHES. A common term among seamen for the Archipelago. (_See_ also GALLEY-ARCHES.)

ARCHI-GUBERNUS. The commander of the imperial s.h.i.+p in ancient times.

ARCHIMEDES' SCREW. An ingenious spiral pump for draining docks or raising water to any proposed height,--the invention of that wonderful man. It is also used to remove grain in breweries from a lower to a higher level. The name has been recently applied to the very important introduction in steam navigation--the propelling screw. (_See_ SCREW-PROPELLER.)

ARCHING. When a vessel is not strongly built there is always a tendency in the greater section to lift, and the lower sections to fall; hence the fore and after ends droop, producing arching, or _hogging_ (which see).

ARCHIPELAGO. A corruption of Aegeopelagus, now applied to cl.u.s.ters of islands in general. Originally the aegean Sea. An archipelago has a great number of islands of various sizes, disposed without order; but often contains several subordinate groups. Such are the aegean, the Corean, the Caribbean, Indian, Polynesian, and others.

ARCHITECTURE. _See_ NAVAL ARCHITECTURE.

ARCTIC. Northern, or lying under _arktos_, the Bear; an epithet given to the north polar regions comprised within the _arctic circle_, a lesser circle of the sphere, very nearly 23 28' distant from the north pole.

ARCTIC OCEAN. So called from surrounding the pole within the imaginary circle of that name.

ARCTIC POLE. The north pole of the globe.

ARCTURUS. a Bootis. A star of the first magnitude, close to the knee of Arctophylax, or Bootes. One of the nautical stars.

ARD, OR AIRD. A British or Gaelic term for a rocky eminence, or rocks on a wash: hence the word _hard_, in present use. It is also an enunciation.

ARDENT. Said of a vessel when she gripes, or comes to the wind quickly.

ARE. The archaism for _oar_ (which see). A measure of land in France containing 100 square metres.

AREA. The plane or surface contained between any boundary lines. The superficial contents of any figure or work; as, the _area_ of any square or triangle.

ARENACEOUS. Sandy; partaking of the qualities of sand; brittle; as, _arenaceous_ limestone, quartz, &c.

ARENAL. In meteorology, a cloud of dust, often so thick as to prevent seeing a stone's-throw off. It is common in South America, being raised by the wind from adjoining sh.o.r.es. Also off the coast of Africa at the termination of the desert of Zahara.

ARENATION. The burying of s...o...b..tic patients up to the neck in holes in a sandy beach, for cure; also spreading hot sand over a diseased person.

AREOMETER. An instrument for measuring the specific gravity of fluids.

ARGIN. An old word for an _embankment_.

ARGO. A name famous from Jason's romantic expedition, but absurdly quoted as the first s.h.i.+p, for the fleets of Danaus and Minos are mentioned long before, and the _Argo_ herself was chased by a squadron under aeetes.

ARGO NAVIS. The southern constellation of the s.h.i.+p, containing 9 cl.u.s.ters, 3 nebulae, 13 double and 540 single stars, of which about 64 are easily visible. As most of these were invisible to the Greeks, the name was probably given by the Egyptians.

ARGOL. The tartaric acid or lees adhering to the sides of wine-casks, particularly of port-wine; an article of commerce; supertartrate of pota.s.s.

ARGOLET. A light horseman of the middle ages.

ARGONAUTA. The paper-nautilus. The sail which it was supposed to spread to catch the wind, is merely a modified arm which invests the outer surface of the sh.e.l.l.

ARGONAUTS. A company of forty-four heroes who sailed in the _Argo_ to obtain the golden fleece; an expedition which fixes one of the most memorable epochs in history. Also a Geographical Society inst.i.tuted at Venice, to whom we owe the publication of all the charts, maps, and directories of Coronelli.

ARGOSY. A merchant s.h.i.+p or carrack of burden, princ.i.p.ally of the Levant; the name is by some derived from Ragusa, but by others with more probability from the _Argo_. Shakspeare mentions "argosies with portly sail." Those of the Frescobaldi were the richest and most adventurous of those times.

ARGOZIN, OR ARGNESYN. The person whose office it was to attend to the shackles of the galley-slaves, over whom he had especial charge.

ARGUMENT. An astronomical quant.i.ty upon which an equation depends,--or any known number by which an unknown one proportional to the first may be found.

ARGUMENT OF LAt.i.tUDE. The distance of a celestial body from one of the nodes of its...o...b..t, upon which the lat.i.tude depends.

ARIES. The most important point of departure in astronomy. A northern constellation forming the first of the twelve signs of the zodiac, into which the sun enters about the 20th of March. With Musca, Aries contains 22 nebulae, 8 double and 148 single stars, but not above 50 are visible to the una.s.sisted eye. The commencement of this sign, called the first point of Aries, is the origin from which the right ascensions of the heavenly bodies are reckoned upon the equator, and their longitudes upon the ecliptic.

ARIS. Sharp corner of stones in piers and docks.

ARIS PIECES. Those parts of a made mast which are under the hoops.

ARITHMETIC. The art of computation by numbers; or that branch which considers their powers and properties.

ARK. The sacred and capacious vessel built by Noah for preservation against the flood. It was 300 cubits in length, 50 in breadth, and 30 in height; and of whatever materials it was constructed, it was pitched over or pay'd with bitumen. _Ark_ is also the name of a mare's-tail cloud, or cirrhus, when it forms a streak across the sky.

ARLOUP. An archaism for the deck, now called _orlop_ (which see).

ARM. A deep and comparatively narrow inlet of the sea. That part of an anchor on which the palm is shut. The extremity of the bibbs which support the trestle-trees. Each extremity or end of a yard, beam, or bracket.--_To arm_, to fit, furnish, and provide for war; to cap and set a loadstone; to apply putty or tallow to the lower end of the lead previous to sounding, in order to draw up a specimen of the bottom.--_To arm a shot_, is to roll rope-yarns about a cross-bar-shot, in order to facilitate ramming it home, and also to prevent the ends catching any accidental inequalities in the bore.

ARMADA. A Spanish term signifying a royal fleet; it comes from the same root as army. The word _armado_ is used by Shakspeare.

ARMADILLA. A squadron of guarda-costas, which formerly cruized on the coasts of South America, to prevent smuggling.

ARMADOR. A Spanish privateer.