the chief and most necessary part of a thing. The principal of a college or hall is the master thereof.

In commerce, principal is the capital of a sum due or lent; so called in opposition to interest. See INTEREST.

It also denotes the first fund put by partners into a common stock, by which it is distinguished from the calls or accessions afterwards required.

in Music. See FUNDAMENTAL, in Music, and GENERATOR, in Music.

in Law, is either the actor or absolute perpetrator of the crime, who is called a principal, in the first degree; or he who is present, aiding and abetting the fact to be done, who is denominated a principal in the second degree. The presence of a principal need not not always be an actual immediate standing by, within sight or hearing of the fact; but there may be also a constructive presence, as when one commits a robbery or murder, and another keeps watch or guard at some convenient distance. And this rule has also other exceptions; for, in case of murder by poisoning, a man may be a principal felon by preparing and laying the poison, or giving it to another (who is ignorant of its poisonous quality) for that purpose; and yet not administer it himself, nor be present when the very deed of poisoning is committed. And the same reasoning will hold, with regard to other murders committed in the absence of the murderer, by means which he had prepared before-hand, and which probably could not fail of their mischievous effect. As by laying a trap or pit-fall for another, whereby he is killed; letting out a wild beast, with an intent to do mischief; or exciting a madman to commit murder, so that death thereupon ensues: in every one of these cases the party offending is guilty of murder as a principal, in the first degree. For he cannot be called an accessory, that necessarily presupposing a principal; and the poison, the pit-fall, the beast, or the madman, cannot be held principals, being only the instruments of death. As therefore he must be certainly guilty, either as principal or accessory, and cannot be so as accessory, it follows that he must be guilty as principal; and if principal, then in the first degree; for there is no other criminal, much less a superior in the guilt, whom he could aid, abet, or assist.

**PRINCIPAL Point, in Perspective,** is a point in the perspective plane, upon which a line drawn from the eye perpendicular to the plane falls.

This point is in the intersection of the horizontal and vertical plane; and is also called the *point of sight,* and *point of the eye.* See **PERSPECTIVE.**

**PRINCIPAL Ray, in Perspective,** is that which passes perpendicularly from the spectator's eye to the perspective plane, or picture.

Whence the point where this ray falls on the plane, is by some also called the *principal point,* which other writers call the *centre of the picture,* and the *point of concurrence.*

**PRINCIPATO,** the name of a province of Italy, in the kingdom of Naples, which is divided into two parts, called by the Italians the *Principato Ultra,* and the *Principato Citra,* the Hither and Farther Principato. The Hither Principato is bounded on the north by the Farther Principato and part of the Terra-di-Lavoro, on the west and south by the Tuscan sea, and on the east by the Basilicata. It is about 60 miles in length, and 30 in breadth; the soil is fertile in wine, corn, oil, and saffron; and they have a great deal of silk, besides several mineral springs. The capital town is Salerno. The Farther Principate is bounded on the north by the county of Molise and the Terra-di-Lavoro, on the west by the Tuscan sea, on the south by the Hither Principato, and on the east by the Capitanata. It is about 37 miles in length, and 30 in breadth. The Apennine mountains render the air cold; and the soil is not very fertile either in corn or wine, but it produces chestnuts, and pastures in great plenty. Benevento is the capital town. The population of both in 1817 was 764,000.

**PRINCIPLE,** **PRINCIPIUM,** in general, is used for the cause, source, or origin of any thing.

**PRINCIPLE,** in human nature. See **DISPOSITION.**

**PRINCIPLE,** in science, is a truth, admitted without proof, from which other truths are inferred by a chain of reasoning. Principles are of two kinds, *primary* and *general,* and to the last the name of *axioms* is usually given on account of their importance and dignity. An axiom or *general* principle, when the terms in which it is expressed are understood, must be a self-evident truth; but from its very nature it cannot be a *first* truth. Our first truths are all *particular.* A child knows that two particular lines, each an inch long, are equal to one another, before he has formed any *general* notions of length and equality. "Things equal to one and the same thing are equal to one another," is the first of Euclid's axioms; and an axiom it undoubtedly is, but to no man has it been a *first* truth. It is, if we may use the expression, a *genus* or *class* of truths, comprehending under it numberless individuals. Were a full-grown man introduced into the world, without a single idea in his mind, as we may suppose Adam to have been, he would instantly perceive, upon laying together three pieces of wood each a foot long, that they were all equal in length; and if he were to cut another to the same length with any one of them, he would find upon trial that it was of the same length with them all. After a few simple experiments of this kind, he would, by a law of human thought, infer, that all things equal in length or in any other dimension, to any one thing, are in that dimension equal to one another.

It was not therefore with such weakness as some have imagined, that Hobbes affirmed those propositions commonly called axioms, not to be primary but secondary principles. A primary principle deserves not the name of an axiom, as it is only a particular truth including in it no other truth. There is not one of Euclid's axioms which has not been the result of induction, though we remember not the time at which the induction was made. That the whole is greater than any of its parts is a general truth which no man of common sense can controvert; but every one discovered that truth by observing that his body was larger than his head, his foot, or his hand; that a mountain is larger than a mole-hill in the middle of it; and that a piece of timber measuring what is called a yard is longer than any one of the divisions marked upon it, and termed inches. The particular observations are made through the senses and treasured up in the memory; and the intellect, by its constitution, compares them together, marks in what they agree and disagree, and thence draws its *axioms* or *general* principles. He, therefore, who should admit the truth of an axiom, and deny the evidence of sense and perception, would act as absurdly as he who accepts payment in a bank-bill, and refuses it in the individual pieces of gold or silver which that bill represents. General axioms are of infinite use in the pursuits of science; but it is not because they create new truths; they only shorten the process in the discovery of such as might be found, with labour, through the medium of particular propositions. See Campbell's Philosophy of Rhetoric and Tatham's Chart and Scale of Truth.

**PRINCIPLES,** in Physics, are often confounded with elements, or the first and simplest parts whereof natural bodies are compounded, and into which they are again resolvable by the force of fire.

**PRINGLE,** Sir John, an eminent physician and philosopher, philosopher, was a younger son of Sir John Pringle of Stichell, in the shire of Roxburgh, Baronet; took the degree of M.D. at Leyden, 1733; and published there Dissertatio Inauguralis de Marcere Senili, 4to. After having been some years professor of moral philosophy at Edinburgh, he was in June 1745 appointed physician to the duke of Cumberland, and physician-general to the hospital of the forces in Flanders, where the earl of Stair appears to have been his patron. In February 1746, Dr Pringle, Dr Armstrong, and Dr Barker, were nominated physicians to the hospital of lame, maimed, and sick soldiers, behind Buckinghamhouse; and in April 1749, Dr Pringle was appointed physician in ordinary to the king. In 1750 he published Observations on the Nature and Cure of Hospital and Gaol Fevers, in a letter to Dr Mead," 8vo (reprinted in 1755); and in 1752 he favoured the public with the result of his long experience, in an admirable treatise under the title of Observations on the Disorders of the Army in Camp and Garrison," 8vo. On the 14th of April 1752, he married Charlotte, second daughter of Dr Oliver, an eminent physician at Bath. In 1756 he was appointed jointly with Dr Wintringham (now Sir Clifton Wintringham, Bart.) physician to the hospital for the service of the forces of Great Britain. After the accession of his present majesty, Dr Pringle was appointed physician to the queen's household, 1761; physician in ordinary to the queen in 1763; in which year he was admitted of the college of physicians in London; and on the 31st of June 1766, he was advanced to the dignity of a baronet of Great Britain. In 1772 he was elected president of the Royal Society, where his speeches for five successive years, on delivering the prize-medal of Sir Godfrey Copley, gave the greatest satisfaction. Sir John Pringle in 1777 was appointed physician extraordinary to the king. He was also a fellow of the College of Physicians at Edinburgh, and of the Royal Medical Society at Paris; member of the Royal Academies at Paris, Stockholm, Gottingen, and of the Philosophical Societies at Edinburgh and Haarlem; and continued president of the Royal Society till November 1778; after which period he gradually withdrew from the world, and in 1781 quitted his elegant house in Pall Mall (where he had long distinguished himself as the warm friend and patron of literary men of every nation and profession), and made an excursion to his native country. He returned to London in the latter end of the year; died greatly beloved and respected, January 18, 1782; and having no children, was succeeded in estate, and also (agreeably to the limitation of the patent) in title, by his nephew, Sir James Pringle, Bart. Among the worthy physician's communications to the Royal Society, the following are the principal: 1. Some Experiments on Substances resisting Putrefaction," Phil. Trans. No. 495, p. 380; and No. 496, p. 325, 350; reprinted, with additions, in Martin's Abridgement, vol. xi. p. 1365. 2. "Account of some Persons seized with the Gaol Fever by working in Newgate, and of the manner by which the Infection was communicated to one entire Family," vol. xlviii. p. 42. At the request of Dr Hales, a copy of this useful paper was inserted in the Gentleman's Magazine, 1753, p. 71, before its appearance in the Transactions. 3. "A remarkable Case of Fragility, Flexibility, and Dissolution of the Bones," ib. p. 297. 4. "Account of the Earthquake felt at Brussels," vol. xlix. p. 546. 5. "Account of the sinking of a river near Pontypool, in Monmouthshire," ib. p. 547. 6. "Account of an Earthquake felt Feb. 18, 1756, along the coast of England, between Margate and Dover," ib. p. 579. 7. "Account of the Earthquake felt at Glasgow and Dumbarton; also of a shower of Dust falling on a Ship between Shetland and Iceland," ib. p. 589. 8. "Several Accounts of the Fiery Meteor which appeared on Sunday, November 26, 1758, between eight and nine at night," vol. i. p. 218. 9. "Account of the Virtues of Soap in dissolving the Stone, in the Case of the Reverend Mr Matthew Simson," ib. p. 221. 10. "Account of the effects of Electricity in Paralytic Cases," ib. 481. And see a letter to him on that subject from Professor Winthorp. Some Account of the Success of the Vitrum Ceratum Antimonii," was printed in the Edinburgh Medical Essays, vol. v.