Omer, Homer, or Chomer,** in the Jewish antiquities, a measure containing 10 baths or 75 gallons and five pints, as a measure of things liquid, and 32 pecks and 1 pint as a measure for things dry. The corus or omer was most commonly a measure for things dry; and the greatest that was used among the Jews. It contained, according to the rabbins, 10 ephahs or 30 sata or sheas. Corus is the most usual term in the historical writers, and omer or chomer among the prophets.

Corus is also used in some of our old writers for eight bushels or a quarter; decem coros tritici, five decem quarteria.

**CORUSCATION,** a glittering or gleam of light issuing from anything. It is chiefly used for a flash of lightning darting from the clouds in time of thunder.

There is a method of producing artificial coruscations, or sparkling fiery meteors, which will be visible not only in the dark but at noon-day, and that from two liquors actually cold. The method is this. Fifteen grains of solid phosphorus are to be melted in about a drachm of water; when this is cold, pour upon it about two ounces of oil of vitriol; let these be shaken together, and they will at first heat, and afterwards they will throw up fiery balls in great number, which will adhere like to many stars to the sides of the glass, and continue burning a considerable time; after this, if a small quantity of oil of turpentine is poured in, without shaking the phial, the mixture will of itself take fire, and burn very furiously. The vessel should be large, and open at the top.

Artificial coruscations may also be produced by means of oil of vitriol and iron, in the following manner: Take a glass bottle capable of holding three quarts; put into this three ounces of oil of vitriol and twelve ounces of water; then warming the mixture a little, throw in, at several times, two ounces or more of clean iron filings; upon this an ebullition and white vapours will arise: then present a lighted candle to the mouth of the vessel, and the vapour will take fire, and afford a bright fulmination or flash like lightning. Applying the candle in this manner several times, the effect will always be the same; and sometimes, the fire will fill the whole body of the glass, and even circulate to the bottom of the liquor; at others, it will only reach a little way down its neck. The great caution to be used in making this experiment is the making the vapour of a proper heat: for, if too cold, few vapours will arise; and, if made too hot, they will arise too fast and will only take fire in the neck of the glass, without any remarkable coruscation.

**CORVORANT,** formerly written Cormorant. See Pelicanus, Ornithology Index.

**CORVUS,** the Raven or Crow kind, a genus of birds of the order of picce. See Ornithology Index.

**Corvus** (Raven), in Astronomy, a constellation of the southern hemisphere; whose stars in Ptolemy's catalogue are 7; in Tycho's as many; in the Britannic catalogue 9.