AZO]                              NAUTICAL  DICTIONARY.

by ship's head and the true course on the same card. The instru¬
ment consists of a double disc of metal, swinging freely on a
tripod, and is of sufficient weight to be always horizontal, what¬
ever may be the list of the ship. The outer rim of the disc is
graduated to the points (or degrees) of the compass, and turning
on the same centre is a second disc similarly graduated.    There
 

is a small pointer for indicating the direction of the ship's head ;
and it is also fitted with a style for obtaining the sun's shadow,
but this can be removed, and the ordinary telescope and sight
vane applied in the usual mode of taking an azimuth of an object.'
(Practical Mechanic and Engineer's Magazine.)

AZOGA. A name given to the Spanish vessels which carried
into America the quicksilver to be used in working the gold mines.
(Dictionnaire de Marine a voiles.)

BACK AN ANCHOE.    See Anchor, 10.

BACK ASTEEN, in rowing, means to reverse the action of
the oars (or, as it is called, to back the oars) so that the boat may
move astern. The oars may be backed also on one side only, in
order to assist in bringing the boat's head speedily round in this
direction. A sailing vessel is backed by means of the sails; a
steamer, by reversing the paddles or screw propeller, or in other
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