POLAR a.
ining to, reckoned from, or having a common radiating point; as, polar coördinates. Polar axis, that axis of an astronomical instrument, as an equatorial, which is parallel to the earths axis. -- Polar bear (Zoöl.), a large bear (Ursus, or Thalarctos, maritimus) inhabiting the arctic regions. It sometimes measures nea…
POSITIVE a.
inary ray is greater than for the ordinary ray, and the former is refracted nearer to the axis than the latter, as quartz and ice; -- opposed to negative crystal, or one in which this characteristic is reversed, as Iceland spar, tourmaline, etc. -- Positive degree (Gram.), that state of an adjective or adverb which de…
PRISM n.
A form the planes of which are parallel to the vertical axis. See Form, n., 13. Achromatic prism (Opt.), a prism composed usually of two prisms of different transparent substances which have unequal dispersive powers, as two different kinds of glass, especially flint glass and crown glass, the difference of dispersive…