PROA

PROA, FLYING, in navigation, is a name given to a vessel used in the South seas, because with a brisk trade-wind

Proa, Probability. trade-wind it fails near 20 miles an hour. In the construction of the proa, the head and stern are exactly alike, but the sides are very different; the side intended to be always the lee-side being flat; and the windward side made rounding, in the manner of other vessels; and, to prevent her over-setting, which, from her small breadth, and the straight run of her leeward side, would, without this precaution, infallibly happen, there is a frame laid out from her to windward, to the end of which is fastened a log, fashioned into the shape of a small boat, and made hollow. The weight of the frame is intended to balance the proa, and the small boat is by its buoyancy (as it is always in the water) to prevent her over-setting to windward; and this frame is usually called an outrigger. The body of the vessel is made of two pieces joined endwise, and sewed together with bark, for there is no iron used about her; she is about two inches thick at the bottom, which, at the gunwale, is reduced to less than one. The sail is made of matting, and the mast, yard, boom, and outriggers, are all made of bamboo. See Anson's Voyage, quarto, p. 341.

PROBABILITY is a word of nearly the same import with likelihood. It denotes the appearance of truth, or that evidence arising from the preponderance of argument which produces opinion. (See OPINION.) Locke classes all arguments under the heads of demonstrative and probable: Hume with greater accuracy divides them into demonstrations, proofs, and probabilities. Demonstration produces science; proof, belief; and probability, opinion.

Hardly any thing is susceptible of strict demonstration besides the mathematical sciences, and a few propositions in metaphysical theology. Physics rest upon principles, capable, some of them, of complete proof by experience, and others of nothing more than probability by analogical reasoning. What has uniformly happened, we expect with the fullest confidence to happen again in similar circumstances; what has frequently happened, we likewise expect to happen again; but our expectation is not confident. Uniform experience is proof; frequent experience is probability. The strongest man has always been able to lift the greatest weight; and, therefore, knowing that one man is stronger than another, we expect, with confidence, that the former will lift more than the latter. The best disciplined army has generally proved victorious, when all other circumstances were equal. We therefore expect that an army of veterans will, upon fair ground, defeat an equal number of new levied troops: but as sudden panics have sometimes seized the oldest soldiers, this expectation is accompanied with doubt, and the utmost that we can say of the expected event is, that it is probable; whereas in the competition between the two men, we look upon it as morally certain. (See METAPHYSICS, Part I. chap. vii. sec. 3.) When two or three persons of known veracity attest the same thing as consistent with their knowledge, their testimony amounts to proof, if not contradicted by the testimony of others; if contradicted, it can, at the utmost, amount only to probability. In common language we talk of circumstantial proofs and presumptive proofs; but the expressions are improper, for such evidence amounts to nothing more than probability. Of probability there are indeed various degrees, from the confines of certainty down to the confines of impossibility; and a variety

of circumstances tending to the same point, though they amount not to what, in strictness of language, should be called proof, afford to the mind a very high degree of evidence, upon which, with the addition of one direct testimony, the laws of many countries take away the life of a man.

PROBABILITY of an Event, in the Doctrine of Chances, is greater or less according to the number of chances by which it may happen or fail. (See EXPECTATION.) The probability of life is liable to rules of computation. In the Encyclopedie Methodique, we find a table of the probabilities of the duration of life, constructed from that which is to be found in the seventh volume of the Supplements à l'Histoire de M. de Buffon; of which the following is an abridgement.

Of 23994 children born at the same time, there will probably die

PROBATE of a will or testament, in Law, is the exhibiting and proving of last wills and testaments before the ecclesiastical judge delegated by the bishop, who is ordinary of the place where the party died.