The usual appellation for a telescope (see the old sea song of Lord Howard's capture of Barton the pirate). Also, the familiar term for a barometer. Glass is also used in the plural to denote time-glass on the duration of any action; as, they fought yard-arm and yard-arm three glasses, i.e. three half-hours.
♦ To flog or sweat the half-hour glass. To turn the sand-glass before the sand has quite run out, and thus gaining a few minutes in each half-hour, make the watch too short.
♦ Half-minute and quarter-minute glasses, used to ascertain the rate of the ship's velocity measured by the log; they should be occasionally compared with a good stop watch.
♦ Night-glass. A telescope adapted for viewing objects at night.