in Antiquity, the name of a vessel in use amongst the Romans for the measuring of liquids. It was at first denominated amphora; and afterwards quadrantal, from its form, which was square every way like a die. Quadrat In capacity it contained eighty librae or pounds of water, which made forty-eight sextaries, two urnae, or eight congi. Quadriga, QUADRAT, a mathematical instrument, called also a Geometrical Square, and Line of Shadows. It is frequently an additional member on the face of the common quadrant, as also on those of Gunter and Sutton.