OCKHAM, or Oakum,** in sea-language, denotes the matter of old ropes untwisted and pulled out into loose hemp, in order to be used in caulking the seams, tree-nails, and bends of a ship, for stopping or preventing leaks.

**OAKHAMPTON,** a town of Devonshire, which sends two members to parliament; situated in W. Long. 4° 5'. N. Lat. 50° 48'.

**OANNES,** a being in Chaldean mythology, represented as half a man and half a fish. According to Berosus and other fabulous writers, this monster was the civilizer of the Chaldeans; to whom he taught a system of jurisprudence so perfect as to be incapable of improvement. In discharging the duties of his office, he spent the day on dry land, but retired every night into the ocean or the river. See **MYTHOLOGY**, n°25.

**OAR,** a long piece of timber, flat at one end and round or square at the other; and which being applied to the side of a floating vessel, serves to make it advance upon the water.

That part of the oar which is out of the vessel, and which enters into the water, is called the **blade**, or **wing-blade**; and that which is within-board is termed the **loom**, whose extremity being small enough to be grasped by the rowers, or persons managing the oars, is called the **handle**.

To push the boat or vessel forwards by means of this instrument, the rowers turn their backs forward, and, dipping the blade of the oar in the water, pull the handle forward so that the blade at the same time may move aft in the water: but since the blade cannot be so moved, without striking the water, this impulsion is the same as if the water were to strike the blade from the stern towards the head: the vessel is therefore necessarily moved according to this direction. Hence it follows, that she will advance with the greater rapidity, by as much as the oar strikes the water more forcibly. Thus it is evident, that an oar acts upon the side of a boat or vessel like a lever of the second class, whose fulcrum is the station upon which the oar rests on the boat's gunnel. In large vessels, this station is usually called the **row-port**; but in lights and boats it is always termed the **row-lock**.

**OARISTUS,** or **OARISTYS,** a term in the Greek poetry, signifying a dialogue between a husband and his wife; such as that in the fifth book of the Iliad between Hector and Andromache.

Scaliger observes, that the oaristus is not properly any particular little poem, or entire piece of poetry; but always a part of a great one. He adds, that the passage now cited in Homer is the only proper oaristus extant in the ancient poets.

**OAT,** in botany. See **AVENA**.

Under the word **AVENA** it was observed, that the native place of the common oat, cultivated in our fields, is unknown; that the only account of it, in its natural state, which we then had, is in Anfon's Voyage; and that the report of such an author respecting facts in natural history is not intitled to implicit credit. We had not then seen the Travels of Mr Bruce, whose botanical knowledge is very superior to that of most voyagers, or we should have mentioned his account of the oats which he found growing wild in Arooffi, a small territory in Abyssinia, not far from the source of the Nile: (See Nile). "Wild oats (says he) grow up here spontaneously to a prodigious height and size, capable often of concealing both the horse and his rider, and some of the stalks being little less than an inch in circumference. They have, when ripe, the appearance of small canes. The inhabitants make no sort of use of this grain in any period of its growth: the uppermost thin husk of it is beautifully variegated with a changeable purple colour; the taste is perfectly good. I often made the meal into cakes in remembrance of Scotland." Our author informs us, that the Abyssinians could never be brought to relish these cakes, which they said were bitter, burnt their stomachs, and made them thirsty. He is, however, decidedly of opinion, that the wild oat of Arooffi is the oat in its original state; and that it has degenerated everywhere in Europe. From the facts which he states, this opinion seems to be well founded.