in Ancient Geography, a large and rapid river of India, which Alexander passed in his expedition into that country. The kingdom of Porus, which was conquered by Alexander, lay between the Hydaspes and this river, which, uniting with the former and other considerable rivers, pours its waters into the Indus. According to Major Rennell, the modern Chuab is the Acesines of the ancients.

Acesius, a bishop of Constantinople in the reign of Constantine, was a rigid adherent to the Novatian doctrines, according to which those whom persecutions had shaken from the faith, or who were guilty of any mortal sin after baptism, could not be admitted to the communion of the church, even after exhibiting the most convincing proofs of sincere repentance. Constantine, who was extremely displeased with the severity of this rigid sect, in discouraging and rejecting repentance, is said to have thus expressed himself: "Then, Acesius, make a ladder for yourself, and go up to heaven alone."

Acetabulum, in antiquity, a measure used by the ancients, equal to one-eighth of our pint. It seems to have acquired its name from a vessel in which acetum or vinegar was brought to their tables, and which probably contained about this quantity.

Acetabulum, in Anatomy, a cavity in any bone for receiving the protuberant head of another, and thereby forming that species of articulation called Enarthrosis.

Acetabulum, in Botany, the trivial name of a species of the peziza, or cup peziza, a genus belonging to the cryptogamia fungi of Linneus. It has got the name of acetabulum from the resemblance its leaves bear to a cup.

Acetary. Grew, in his Anatomy of Plants, applies this term to a pulpy substance in certain fruits, e.g. the pear, which is inclosed in a congeries of small calculous bodies towards the base of the fruit, and is always of an acid taste.

Acetosa, Sorrel; by Linnaeus joined to the genus Rumex.

Acetosella, in Botany, a species of Oxalis.

Acetous, an epithet applied to such substances as are sour, or partake of the nature of vinegar.

Acetum, Vinegar, the vegetable acid of the chemists.

Achaea, in Ancient Geography, a town of the island of Rhodes, in the district of Ialysus, and the first and most ancient of all; said to be built by the Heliades, or grandsons of the sun.

Achaeans, the inhabitants of Achaia Propria, a Peloponnesian state. This republic was not considerable, in early times, for the number of its troops, nor for its wealth, nor for the extent of its territories; but it was famed for its probity, its justice, and its love of liberty. Its high reputation for these virtues was very ancient. The Crotonians and Sybarites, to re-establish order in their towns, adopted the laws and customs of the Achaeans. After the famous battle of Leuctra, a difference arose betwixt the Lacedemonians and Thebans, who held the virtue of this people in such veneration, that they terminated the dispute by their decision. The government of the Acheans was democratical. They preserved their liberty till the time of Philip and Alexander; but in the reign of these princes, and afterwards, they were either subjected to the Macedonians, who had made themselves masters of Greece, or oppressed by domestic tyrants. The Achean commonwealth consisted of twelve inconsiderable towns in Peloponnesus. Towards the 124th Olympiad, about the time when Ptolemy Soter died, and when Pyrrhus invaded Italy, the republic of the Acheans recovered its old institutions and unanimity. The inhabitants of Patra and of Dyne were the first assertors of ancient liberty. The tyrants were banished, and the towns again made one commonwealth. A public council was then held, in which affairs of importance were discussed and determined. A register was appointed to record the transactions of the council. This assembly had two presidents, who were nominated alternately by the different towns. But instead of two presidents, they soon elected but one. Many neighbouring towns, which admired the constitution of this republic, founded on equality, liberty, the love of justice, and of the public good, were incorporated with the Acheans, and admitted to the full enjoyment of their laws and privileges.—The arms which the Acheans chiefly used were slings. They were trained to the art from their infancy, by slinging from a great distance, at a circular mark of a moderate circumference. By long practice they took so nice an aim, that they were sure, not only to hit their enemies on the head, but on any part of the face they chose. Their slings were of a different kind from those of the Balearians, whom they far surpassed in dexterity.

ACHÆI, ACHÆANS, the inhabitants of Achaia Propria. In Livy, the people of Greece; for the most part called Achivi by the Roman poets. In Homer, the general name for Grecians. See ACHÆANS.

ACHÆMENES, according to Herodotus, was grandfather of Cambyses, and great-grandfather of Cyrus the first, king of Persia. Most of the commentators of Horace are of opinion, that the Achaemenes whom that poet mentions, Ode xii. of his 2d book, was one of the Persian monarchs; but if that were true, he must have reigned before the Medes subdued the Persians; for we do not hear of any king of that name from the time that the Persians founded that great monarchy, which is looked upon as the second universal one. However this be, the epithet Achaemenian is frequently given to the Persians in the old Latin poets.

ACHEMENES, son of Darius I. king of Persia, and brother of Xerxes, had the government of Egypt bestowed on him, after Xerxes had forced the Egyptians to return to their allegiance. He some time after commanded the Egyptian fleet in the celebrated expedition which proved so fatal to all Greece. The Egyptians having again taken up arms after the death of Xerxes, Achaemenes was sent into Egypt to suppress the rebellion, but was vanquished by Inarus, chief of the rebels, succoured by the Athenians.

ACHÆUS, cousin-german to Seleucus Ceraunus and Antiochus the Great, kings of Syria, became a very powerful monarch, and enjoyed the dominions he had usurped for many years; but at last he was punished for his usurpations in a dreadful manner, in the 140th year of Rome, as related by Polybius.1