PEN, WRITING-PENS. It is well known that the ancients employed a certain reed, the nature of which is not precisely ascertained, for writing. The reeds were split, and shaped to a point like our quills. When goose-quills first came into use, or who first borrowed from the emblem of folly the instruments of wisdom, is not known. It has been asserted, that quills were used for writing as early as the fifth century, according to the history of Constantius. The oldest certain account is a passage of Isidore, who died 636 A. D., and who, among the instruments employed for writing, mentions reeds and feathers. There exists, also, a poem on a pen, written in the same century, and to be found in the works of Adhelm, the first Saxon who wrote in Latin. Alcuin (q. v.), the friend and teacher of Charlemagne, mentions writing-pens in the eighth century. After that time, proofs exist which put the question of their use beyond dispute. Mabillon (q. v.) saw a manuscript gospel of the ninth century, in which the evangelists were represented with pens in their hands. Calami properly signify the Ireeds which the ancients used in writing. Modern authors often use the word as a Latin term for pens, and it is probable that the same was employed to signify quills before the time of Isidore. Reeds were used for a considerable time after the introduction of writing-pens. In convents they were retained a long time for the initials only. By some letters of Erasmus to Reuchlin, it appears that the former received three reeds from the latter, and expressed a wish that Reuchlin, when he procured more, would send some of them to a certain learned man in England. Quills, for some reason, were, about the

year 1433, extremely rare in Venice. We learn from the familiar letters of learned men of that time, that they were equally troubled by the rarity of quills and by the difficulty of making good ink. Of late, steel pens have been much used and improved, and for certain purposes, as for signing bank notes, to make the signatures uniform, they appear well adapted; as also for people who cannot make pens; but, on the whole, the quill affords a much easier and handsomer chirography.

PENAL LAW. (See Criminal Law.) PENANCE; every penalty borne for the expiation of an offence. In the early Christian church, this ancient judicial principle was transferred to religious penance, that is, to the atonement which the sinner has to make, for his trespasses, to God and the church. According to the doctrine of the Protestants, it is not among the sacraments. This doctrine considers compunction and faith as the only elements of repentance and reformation. Penance is considered by the Catholic church a sacramental institution.. The conditions for the necessary transition from bad to good, are a humble consciousness of guilt. The conversion itself is a change in the soul of man, effected by the power of God, but necessarily connected with an exterior alteration. The power of forgiving sins, in the literal sense of the word, say the Catholics, has been transferred by Christ to the apostles, and to the church; but the latter can forgive the sins only of the truly repentant and converted sinner. To bring him to the knowledge of himself, the church has established confession; to calm his conscience, absolution; for the instruction and discipline of the converted, she in

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flicts penance, as a satisfaction to his own conscience and to God. Confession was not invented by Innocent III, but only enjoined by him at least once a year. It is followed by absolution, according to the authority transmitted to the church, and by the imposition of such penances as are necessary to free from the consequences of sin. The council of Trent declares, in sess. xiv, c. 8, that satisfaction for sin is effected only by Christ, and it is left for the individual to bring forth fruits worthy of repentance. Days of penance and fasting are holy days, which, in certain countries, are fixed annually, or after general calamities, for the purpose of a general expression of penitence, or with the view of appeasing the anger of the Deity. The great day of fasting among the Jews is the Long Night. The Christians imitated these fast-days.

PENATES; the private or public gods of the Romans; in the former sense, they resembled the Lares (q. v.), with whom they are often confounded. Not only every house, but every city, had its Penates, and the latter were the public gods. The most celebrated at Rome were those that protected the empire. These were brought into Italy by Æneas, together with Vesta and her eternal fire. According to Varro and Macrobius, the Penates were rude images of wood or stone,furnished with a spear; and generals, on their departure, and consuls, pretors and dictators, when they retired from office, sacrificed victims before them. PENCIL; an instrument used by painters for laying on their colors. Pencils are of various kinds, and made of various materials; the larger sorts are made of boar's bristles, the thick ends of which are bound to a stick, large or small, according to the uses they are designed for; these, when large, are called brushes. The finer sorts of pencils are made of camels', badgers' and squirrels' hair, and of the down of swans; these are tied at the upper end with a piece of strong thread, and enclosed in the barrel of a quill Good pencils, when drawn between the lips, come to a fine point.

Lead Pencils. (See Plumbago.)

Pencil of Rays; a number of rays diverging from some luminous point, which, after passing through a lens, converge again to a point.

PENDANT. Two paintings or prints of equal dimensions, which are attached in corresponding positions to the same wall, are called pendants to each other.

PENDANT, OF PENNANT; a sort of long narrow banner displayed from the mast

head of a ship-of-war, and usually terminating in two ends or points, called the swallow's-tail. It denotes that a vessel is in actual service.-Broad pendant is a kind of flag terminating in one or two points, used to distinguish the chief of a squadron.-Pendant is also a short piece of rope, fixed on each side, under the shrouds, upon the heads of the main and fore masts.

PENDULUM, in dynamics, is a simple ponderous body, so suspended by a flexible cord from an axis of suspension, that it is at liberty to vibrate by the action of its own gravity alone, when it is once raised, by any external force, to the right or left of its quiescent position; and, in demonstrating the theory of its motion, mathematicians are obliged to assume, that there is no rigidity in the cord, no friction at the axis of suspension, no resistance to motion made by the air, and no variation in the total length of the cord, arising from the variable temperature or moisture of the atmosphere; and if these assumptions were strictly correct, a pendulum, once put in motion, would continue to move, ad infinitum, without a further accession of any external force; but, when the pendulum is applied as the regulator of a clock, for which purpose it is admirably adapted, the assumptions which we have stated, require an equal number of mechanical corrections, of which the theory, simply considered, takes no notice. In horology, therefore, the pendulum must be considered not simply as a self-moving pendulous body, without any tendency to come to a state of rest, but as a body whose motion is perpetuated by repeated accessions of force in aid of its own gravity, and whose vibrations are rendered isochronal by a nice adaptation of mechanical contrivances, that prevent or remedy the influence of all natural impediments to uniform and uninterrupted motion. The first kind of pendulum (the theoretical) is called a mathematical or simple pendulum, the other the physical or compound pendulum. In the mathematical pendulum, the matter of the pendulous ball or bob is supposed to be collected into one point, so that the centres of gravity and of oscillation coincide. The doctrine of the pendulum is of the highest importance, but, as it cannot be fully developed without the aid of mathematics, nor rendered clear without diagrams, we can state only some of the most obvious properties and circumstances connected with it. A pendulum, once put in motion, would never cease to

oscillate in arcs, were it not for the friction at the point of suspension, and the resistance of the air. Neither of these circumstances can ever be avoided entirely, but their effect may be rendered comparatively slight by giving to the weight a lenticular shape, and suspending the rod on a sharp edge, on which it plays with very little friction. The times of the vibrations of a pendulum depend, 1. on the magnitude of the angle of elongation, viz. that angle by which the heavy body of the pendulum is removed from the vertical line; 2. upon the length of the pendulum; and 3. upon the accelerating power of gravity. If all these circumstances are perfectly equal in the case of two pendulums, they will perform an equal number of oscillations in the same time; but if there is a difference in either of the circumstances, the oscillations will differ immediately. Thus, if one pendulum is shorter than the other, and all the other circumstances equal, the shorter pendulum will move quicker than the longer. The law which has been found to exist is, that the lengths of the pendulums are in an inverse proportion to the squares of their oscillations; hence the times of the oscillations are inversely as the square roots of the lengths of the pendulums. Hence a pendulum which is four times as long as another, will vibrate with but half the rapidity, or the shorter pendulum will perform two oscillations whilst the larger performs but one. The pendulum does not perform its oscillations in equal times in all parts of the earth. This is owing to the third of the circumstances enumerated above, upon which the oscillations depend. The gravity, or, what is the same thing, the power of attraction in the earth, does not operate every where with equal force on the pendulum, which, therefore, in some parts of the earth, oscillates more slowly than in others. The cause of this lies in the centrifugal force (q. v.), or in the diminution of the power of gravity caused by it. This becomes more perceptible the nearer the place where the pendulum is observed is to the equator. (See Earth.) At the equator, therefore, a pendulum vibrating seconds must be somewhat shorter than at a distance from it. The length of a seconds pendulum at the equator is, according to Biot, 39.011684 inches; in latitude 45°, 39.116820, in 90°, 39.221956. If the globe were a perfect spheroid, the meridians would be perfect ellipses, and in such case the length of seconds pendulums would immediately afford a

basis for a calculation of the length of the degrees in the various latitudes; but actual measurements have shown that the meridians contain some irregularities, from which it has been justly concluded, that the earth has not a perfectly regular form, but deviates more or less from the shape of a sphere. We can, therefore, properly draw conclusions from the oscillations of the pendulum respecting the power of gravity only, and not respecting the form of the earth. Besides the friction of the rod, &c., and the resistance of the air, there are also other circumstances which influence the oscillations of the pendulum. These are the changes of heat and cold. Heat lengthens the rod of the pendulum, cold contracts it; hence common pendulum clocks go much quicker in winter; and the change of temperature in rooms which are heated during the day influences them considerably. Many contrivances have been devised for overcoming this inconvenience. One is, by making pendulums of the form of a gridiron, consisting of several parallel bars of different metals, so connected that the effect of one set of them counteracts that of the others. These have been very successful. Rods are sometimes made of certain kinds of wood, well seasoned, which are little influenced by the weather. Astronomical clocks of the present day do not err to the amount of one beat or oscillation of the pendulum in a year. A common clock is merely a pendulum with wheel-work attached to it, to record the number of vibrations, and with a weight or spring to counteract the retarding effects of friction and the resistance of the air. Huygens, who developed the doctrine of the pendulum, which had been treated already by Galileo, first applied it to clocks, and thus became the inventor of the pendulum clock (in 1656). (See Clock.)-For the application of pendulums to horology, see Berthoud's Essai sur l'Horlogerie (Paris, 1763, 2 vols., 4to.).-See, also, Biot's treatise Sur la Longueur du Pendule à Secondes, in the third volume of his Traité d'Astronomie Physique (second edition, Paris, 1810).— See, also, Bode's Anleitung zur Kenntniss der Erdkugel (second edition, Berlin, 1803). PENELOPE. (See Ulysses.) PENGUIN. (See Pinguin.) PENITENTIARIES. (See Prisons.)

PENN, William, was born in London, in 1644. He was the only son of William Penn, of the county of Wilts, vice-admiral of England in the time of Cromwell, and afterwards knighted by king Charles II, for his successful services against the

Dutch. He appears to have been seriously inclined from his youth, having imbibed religious impressions as early as his twelfth year, which were soon afterwards confirmed by the ministry of Thomas Loe, an eminent preacher among the people called Quakers, then newly associated in religious fellowship. In his fifteenth year, he was, notwithstanding, entered as a gentleman commoner of Christ-church, Oxford, where, meeting with some other students who were devoutly inclined, they ventured to hold private meetings among themselves, wherein they both preached and prayed. This gave great offence to the heads of the college, by whom these zealous tyros were at first only confined for non-conformity; but persisting in their religious exercises, they were finally expelled the university. On his return home, his father endeavored in vain to divert him from his religious pursuits, as being likely to stand in the way of his promotion in the world; and at length, finding him inflexible in what he now conceived to be his religious duty, beat him severely, and turned him out of doors. Relenting, however, at the intercession of his mother, and hoping to gain his point by other means, he sent his son to Paris, in company with some persons of quality; whence he returned so well skilled in the French language, and other polite accomplishments, that he was again joyfully received at home. After his return from France, he was admitted of Lincoln's Inn, with a view of studying the law, and continued there till his twenty-second year, when his father committed to him the management of a considerable estate in Ireland a circumstance which unexpectedly proved the occasion of his finally adhering to the despised cause of the Quakers, and devoting himself to a religious life. At Cork, he met again with Thomas Loe, the person whose preaching had af fected him so early in life. At a meeting in that city, Loe began his declaration with these penetrating words, "There is a faith that overcomes the world, and there is a faith that is overcome by the world;" which so affected Penn, that from that time he constantly attended the meetings of the Quakers, though in a time of hot persecution. He was soon afterwards, with many others, taken at a meeting in Cork, and carried before the mayor, by whom they were committed to prison; but young Penn was soon released, on application to the earl of Orrery, then lord president of Munster. His father, being informed of

his conduct, remanded him home; and, finding him unalterably determined to abide by his own convictions of duty, in respect to plainness of speech and deportment, he would have compounded with him, if he would only have consented to remain uncovered before the king, the duke (afterwards James II), and himself. Being disappointed in this, he could no longer endure the sight of his son, and a second time drove him from his family. Yet after a while, becoming convinced of his integrity, he permitted him to return; and though he never openly countenanced him, he would use his interest to get him released, when imprisoned for his attendance at religious meetings. In the year 1668, in the twenty-fourth year of his age, Penn first appeared as a minister and an author; and it was on account of his second essay, entitled the Sandy Foundation Shaken, that he was imprisoned in the Tower, where he remained seven months, during which time he wrote his most celebrated work, No Cross no Crown, and finally obtained his release from confinement by an exculpatory vin- · dication, under the title of Innocency with her open Face. In 1670, the meetings of dissenters were forbidden, under severe penalties. The Quakers, however, believing it their religious duty, continued to meet as usual; and when forcibly kept out of their meeting-houses, they assembled as near to them as they could in the street. At one of these meetings, William Penn preached to the people thus assembled for divine worship; for which pious action he was committed to Newgate, and, at the next session at the Old Bailey, was indicted for "being present at, and preaching to, an unlawful, seditious, and riotous assembly." He pleaded his own cause, though menaced by the recorder, and was finally acquitted by the jury; but he was, nevertheless, detained in Newgate, and the jury fined. Sir William died this year, fully reconciled to his son, to whom he left a plentiful estate, taking leave of him in these memorable words: "Son William, let nothing in this world tempt you to wrong your conscience. So will you keep peace at home, which will be a feast to you in a day of trouble." Shortly after this event, Penn travelled, in the exercise of his ministry, into Holland and Germany. In the year 1672, he married Gulielma Maria Springett, whose father (sir William) having been killed at the siege of Bamber, in the civil wars, her mother had married Isaac Penington, of Chalfont, in Bucks, an eminent minister