FLASH n.
or Flashing light, a kind of light shown by lighthouses, produced by the revolution of reflectors, so as to show a flash of light every few seconds, alternating with periods of dimness. Knight. -- Flash in the pan, the flashing of the priming in the pan of a flintlock musket without discharging the piece; hence, sudd…
GREGORIAN a.
irror in the axis of this telescope, having its focus coincident with that of the large reflector, transmits the light received from the latter back through a hole in its center to the eyepiece placed behind it. -- Gregorian year, the year as now reckoned according to the Gregorian calendar. Thus, every year, of the c…
HORIZON n.
cial horizon, a level mirror, as the surface of mercury in a shallow vessel, or a plane reflector adjusted to the true level artificially; -- used chiefly with the sextant for observing the double altitude of a celestial body. -- Celestial horizon. (Astron.) See def. 2, above. -- Dip of the horizon (Astron.), the ver…