Aureola, Chr. (aurum, gold). A quadrangular, circular, or elliptic halo surrounding the bodies of Christ, the Virgin, or certain saints. Another name for this ornament is the mystical almond or Vesica Piscis (q.v.). When it envelopes the head only it is called the Nimbus.
Aureole. (See Aureola.)
Aureus, R. (sc. nummus, golden). The unit of value for gold currency under the Roman emperors, worth about a guinea.
Auripetrum. A cheap imitation of gold leaf; made of tinfoil coloured with saffron.
Auspicium, R. (aves aspicio). Divination from observation of the flight of birds. (Auspicium ex avibus, signa ex avibus.) There was also the auspicium cœleste or signa ex cœlo, of which the most important was a flash of lightning from a clear sky. Besides these there were the auspicia pullaria, or auspices taken from the sacred chickens; the auspicia pedestria, caduca, &c. (See Augurale.)
Authepsa, Gr. and R. (αὐθέψης). Literally a self-boiler; it was a sort of kettle or cauldron, which was exposed to the rays of the sun, to heat the water within it; whether, however, the ancients had attained the art of raising water to boiling heat, in this manner, it is impossible to say. The apparatus is mentioned by Cicero and Lampridius, but neither of them gives any description of it.
Avellane. A variety of the heraldic cross. (See Crosses.)
Avena, R. (oats). A Pandæan pipe, made of the stalk of the wild oat.
Aventail, Fr. (avant taille). The movable front of a helmet.
Aventurine. A kind of brown glass, mixed with bright copper filings, formerly made at Venice.