name famous from Jason's romantic expedition, but absurdly
quoted as the first ship, 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 Ship, containing 9
clusters, 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
potass.

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 shell.

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 instituted at
Venice, to whom we owe the publication of all the charts, maps, and
directories of Coronelli.

ARGOSY. A merchant ship or carrack of burden, principally 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 quantity upon which an equation depends,--or
any known number by which an unknown one proportional to the first may
be found.

ARGUMENT OF LATITUDE. The distance of a celestial body from one of the
nodes of its orbit, upon which the latitude 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 unassisted 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