Mirror

Smooth surface from which rays of light may be reflected so as to form a virtual image according to regular and fixed laws. Its surface is invisible, other surfaces being made visible by the irregular reflection which takes place. The best mirrors are made of polished silver, and are either plane or curved. Curved mirrors are usually either spherical or parabolic: great accuracy in the construction of the latter is difficult. Ordinary mirrors are a plate of gla backed by an amalgam of tin and mercury. Mirrors of bra were used by the Hebrews; of bronze by the ancient Egyptians, Greeks, and Romans; of silver by the Greeks 328 B.C.; of gla by the Venetians 1300, introduced into England 1673. Silvered gla reflects 91 per cent of light from the silver side, 78 per cent from the gla side; ordinary mirrors, tin amalgam, reflect 44.6 per cent. See MAGIC MIRRORS. Mirza. Persian title, meaning prince when placed after the name, and mere courtesy before it.