MERCURY, in the heathen mythology. (See Hermes.) Most of the actions and inventions of the Egyptian Mercury have likewise been attributed to the Grecian, who was said to be the son of Jupiter and Maia, the daughter of Atlas. No one of all the heathen divinities had so many functions allotted to him as this god. He had constant employment both day and night, having been the common minister and messenger of the whole Pantheon; particularly of his father Jupiter, whom he served with indefatigable labour, and sometimes, indeed, in a capacity of no very honourable kind. Lucian is very pleasant upon the multitude of his avocations; and according to the confession of the Emperor Julian, Mercury was no hero, but one who inspired mankind with wit, learning, and the ornamental arts of life, rather than with courage. The pious emperor, however, omits some of his attributes; for this god was not only the patron of trade, but also of theft and fraud. His most magnificent temple stood upon Mount Cylene, in Arcadia. He is described by the poets as a fair beardless youth, with flaxen hair, lively blue eyes, and a smiling countenance. He has wings fixed to his cap and sandals, and holds the caduceus (or staff, surrounded with serpents, with two wings on the top,) in his hand; and is frequently represented with a purse, to show that he was the god of gain. The animals sacred to him, were the dog, the goat, and the cock. In all the sacrifices offered to him, the tongues of the victims were burnt; and those who escaped imminent danger sacrified to him a calf with milk and honey.

Mercury, ÿ in Astronomy. (See Astronomy.) This planet is brightest between his elongations and superior conjunction, very near to which last he can generally be seen. He becomes invisible soon after he has found his elongation, going towards his inferior conjunction, and becomes visible again a few days before his next elongation. The brightness of this planet alters sometimes very considerably in twenty-four hours. It has been observed when less than three degrees distant from the sun, and may, perhaps, sometimes be seen even in conjunction with it. Mercury and Venus appear brightest and most beautiful in the opposite parts of their orbits; the former between his elongations and superior conjunction, and the latter between her elongations and inferior conjunction. Therefore, Venus is seen in great perfection as a crescent, particularly in her inferior conjunction, whilst Mercury is seldom seen in such perfect phases. Mercury should be always observed on or near the meridian. When farthest from the sun, he always appears with a very faint light; and when he has a great south declination, or the atmosphere is not perfectly clear, he can seldom be seen in those parts of his orbit, where he only begins to recover his brightness, or where it is much diminished. He has frequently been seen on the meridian even with a telescope of small power; and it appears from the above statement that he may be obscured in a clear day rather more than half his orbit, or nearly one hundred and fourscore days in the year.

Mercury, in Heraldry, a term used in blazoning by planets, for the purple colour used in the arms of sovereign princes.

Mercury Bay, situated upon the north-east coast of the northernmost island of New Zealand, so called by Captain Cook-who here observed the transit of Mercury over the sun in 1769. Long. 184.4. N. Lat. 36. 48. S.