on the absolute necessity of having some one to act for another in times and places when the latter is not personally present; and, as a general rule, the act of the agent is just as binding on the principal, and produces the same effect as regards his liability, as if the principal had acted in person. Agents are divided into many classes; indeed, nobody can escape, in one capacity or another, being occasionally the agent of somebody else. Attorneys, solicitors, advocates, brokers, auctioneers, etc., may be said to make a business of agency. A wife is, in law, for many purposes of household management, the agent of the husband, and so are the children of the parents. Mercantile agents are generally called brokers. The contract between P. and A. implies that the agent shall keep within the limits of his commission, and that the principal will ratify and accept all his contracts, and relieve him of the liabilities. "The general principal is that an agent is liable to third persons for acts of misfeasance and positive wrong; but for mere non-feasance and negligence in the course of his employment he is answerable only to his principal, and the principal is answerable to the third party. Since agency is generally a personal trust, the principal employing the agent from the opinion which he has of his personal skill and integrity, the latter cannot as a general thing delegate the confidence reposed in him to another. In some cases, however, a usage of trade has been held to authorize an agent to employ a broker." The remuneration of the agent is generally called his commission. As the agent binds his principal, it follows that the principal can be sued by third parties who deal with the agent. The nice distinctions that exist in the law on this subject, as to the mutual rights and liabilities of the parties, are too numerous to be here noticed.

Principa'to Citeriore, or Saler'no, a prov. of southern Italy, in Campania, bordering on the Tyrrhenian Sea; area 2,126 sq. m., pop. 541,738. It is traversed by branches of the Apennines, being level only near the lower Tusciano and Sele. The fisheries are famous. The region around Vesuvius is like a garden. The cap. is Salerno.

Principa'to Ulteriore, or Avellino, a prov. of southern Italy, in Campania, N. of the preceding; area 1,409 sq. m., pop. 375,691. There are marble quarries and fine pasturage. The districts of Avellino, Ariano, and Sant' Angelo de' Lombardi correspond to three natural divisions formed by the Apennines. The cap. is Avellino.

Princip'ia, the abbreviated name by which the celebrated work of Sir Isaac Newton, Philosophic Naturalis Principia Mathematica, is generally known. The P. has passed through many editions and translations, and is the work in which Newton first explained the motions and forces of the solar system from the laws of universal gravitation.

Prin'gle, (THOMAS,) a British man of letters; one of the early editors of Blackwood's Edinburgh Magazine, the Star, and Constable's Magazine. He emigrated to the Cape of Good Hope in 1820, where he edited the South African Journal, returning to England in 1826. He left many volumes of poems and other writings. B. in Scotland 1789, d. 1834.

Prings heim, (NATHANAEL,) a Ger. botanist of Jewish parentage, b. in Silesia in 1823. He was Prof. of Botany at Jena 1864-68, and is known by his minute researches into the anatomy and physiology of cryptogamous plants, and his works on this and other botanical subjects.

Print'ing, the art of producing impressions from characters or figures on paper or any other substance. There are several distinct branches of this important art-as the P. of books with movable types, the P. with engraved copper and steel plates, and the taking of impressions from stone, called Lithography. We have now to describe the art of P. on sheets, etc., with movable types, generally called letter-press P., and which may undoubtedly be esteemed the greatest of all human inventions. The art of P. is of comparatively modern origin, only 400 yrs. having elapsed since the first book was issued from the press; yet we have proofs that the principles upon which it was ultimately developed existed among the ancient Assyrian nations. Entire and undecayed bricks of the famed city and tower of Babylon have been found stamped with various symbolical figures and hieroglyphic characters. In this, however, as in every similar relic of antiquity, the object which stamped the figures was in one block or piece, and therefore could be employed only for one distinct subject. This, though a kind of P., was totally useless for the propagation of literature, on account both of its expensiveness and tediousness. The Chinese are the only existing people who still pursue this rude mode of P. by stamping paper with

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blocks of wood. The work which they intend to be printed is, in the first place, carefully written upon sheets of thin, transparent paper; each of these sheets is glued, with the face downward, upon a thin tablet of hard wood; and the engraver then, with proper instruments, cuts away the wood in all those parts on which nothing is traced, thus leaving the transcribed characters in relief, and ready for P. In this way as many tablets are necessary as there are written pages. No press is used; but when the ink is laid on, and the paper carefully placed above it, a brush is passed over with the proper degree of pressure. A similar kind of P. by blocks, for the production of playing-cards and rude pictures of scriptural subjects, was in use in Europe toward the end of the 14th c. But in all this there was little merit. great discovery was that of forming every letter or character of the alphabet separately, so as to be capable of rearrangement and forming in succession the pages of a work, thereby

An Ancient Printing Office.

The

avoiding the interminable labor of cutting new blocks of types for every page. The credit of inventing this simple yet marvelous art is contested by the Dutch in favor of Laurence Koster, between 1420 and 1426; and by the Germans on behalf of Johann Gansfleisch, of the Gutenberg family, about 1438. In all probability the discovery was made almost simultaneously-such a theory being consistent with the general social progress at the period, and the secrecy which both inventors at first maintained respecting their art. The types first employed were of wood; but soon the practice of casting them in metal was introduced. The earliest of these metal types resembled the black-letter in use by transcribers, and one great aim of the first printers was to produce books which should closely resemble the works in MS. hitherto in use. Between 1450 and 1455 Gutenberg succeeded in printing a Bible, copies of which are now exceedingly rare and valuable. It is in quarto size, double columns, the initial letters of the chapters being executed with the pen, in colors. Besides this Bible some other specimens of the work of Gutenberg, the produce of his press at Mayence, have been discovered. The Dutch at Haarlem preserve and show with reverential care similar specimens of early P. by Koster. Mayence, Strasburg, and Haarlem were indisputably the places where P. was executed before the art was extended to Rome, Venice, Florence, Milan, Paris, Tours, and other Continental cities. Previous to 1471 it had reached these and various other places; and about the same yr. Caxton introduced the art in England, by setting up a press in Westminster Abbey. As will be seen from the illustration given above, the first P.-presses were of rude and clumsy construction. The first improvement upon the P.-press was made by the celebrated Earl Stanhope. He constructed the press of iron, and that of a size sufficient to print a whole surface of a sheet, and he applied such a combined action of levers to the screw as to make the pull a great deal less

Prints from three rolls of paper, 4, 6, or 8 page papers at a running speed of 72,000 per hour, 10 or 12 page papers at 48,000 per hour, 16 page papers at 36,000 per hour, and 14, 20, or 24 page papers at 24,000 per hour, all delivered, folded, and counted.

by printers. The bed and cylinder being each driven by a crank, and there being no springs required to help reverse the motion of the bed, there is no lost motion between the bed and the cylinder during the printing-stroke. The impression is sharp and solid, and the bed and cylinder are warranted not to spring or give way in the least degree. The distribution is exceptionally fine, the form being rolled with fresh ink on the forward and backward motion of the bed. The two-color and sheet perfecting presses are each in reality two machines combined in one, the sheet perfecting press giving a production at one feeding equal to two feedings on a single-end machine; while on the two-color press two sheets are going through the machine at the same time, there being a transfer cylinder between the two P.-cylinders which takes the sheet from the first cylinder, on which one color has been printed, and transfers it to the second cylinder, on which the second color is to be printed; a fountain at each end of the press supplying the separate forms with ink in the ordinary manner. For high class color work these machines are unequaled, and their value in this branch of the printer's art is gradually being recognized by those who are desirous of keeping pace with the requirements of the times. P.-machines may be divided into two distinct classes-those for printing books, in which accurate register is required, and

was made in the art of rapid P. In 1859 a long series of experiments ended in the successful substitution of curved stereotyped plates for pages of movable type. Besides escaping the risk and wear involved in working pages of type in circular chases, the new method relieves the types from all direct P. work, so that, instead of two yrs., a font may last twenty. The early Hoe machine, however, with all its advantages, retained the inconvenience of printing only one side at a time. These difficulties were first entirely overcome by a new machine, the "Walter," contrived and perfected between 1863 and 1868 by the manager of the London Times establishment, which printed both sides by one operation from a continuous roll of paper. But in the manufacture of fast "perfecting" presses Amer. ingenuity and skill lead the world. We illustrate some modern presses which perform every operation of printing, pasting, folding, and trimming a newspaper. In machines printing from stereotype plates there are (1) what is called the Presto stereotype perfecting machine, delivering 4-page papers at the running speed of 20,000 per hour, 8-page papers at 10,000 per hour, and 2-page supplements at 40,000 per hour, folded halfpage size. (2) Single stereotype perfecting machine, delivering 4-page papers at the running speed of 24,000 per hour, and 8-page papers at the running speed of 12,000

those for printing newspapers, in which register is not sought for and speed is of first consequence. The liberation of English newspapers from the penny-stamp in 1855 caused so great an increase of circulation that none of the ordinary processes was at all adequate for the work required. Recourse had to be made to an entirely new method of P., the invention of which is due to Richard M. Hoe, of New York. Hoe's process consisted in placing the types (for which stereotype plates were afterward substituted) on a horizontal cylinder revolving on its axis, against which the sheets were pressed by exterior and smaller cylinders. The pages of type were arranged in segments of a circle, each segment forming a frame that could be fixed on the cylinder. These frames were technically called turtles. By the ingenious contrivance of making the brass rules that separate the columns of a beveled or wedge shape, the thinner edge being toward the surface of the turtle, the form of type was susceptible of being tightened up and made firm. The forms occupied only a portion of the main cylinder, the remainder affording space for the inking apparatus. The smaller surrounding cylinders for effecting the pressure were arranged in a frame-work in connection with slopes, by which the sheets were fed in blank and came out printed on one side. The size of the main cylinder, the number of exterior cylinders, and the rate of speed determined the number of impressions printed per hour. Such was the method of working Hoe's rotary machines, which, as needed, were made with 2, 4, 6, 8, or 10 subsidiary cylinders. The first introduced into Europe was the one made for the Paris newspaper La Patrie, in 1848, and the next was one with six cylinders for Lloyd's Weekly Newspaper, in London, in 1857. About the time that the Hoe machines came commonly into use another great advance

per hour, folded either half or quarter page size. (3) The 3-page-wide stereotype perfecting press, printing from a single roll of paper 4 or 6 page papers at the running speed of 24,000 per hour, 8 or 12 page papers at 12,000 per hour. (4) Double stereotype perfecting machine, delivering, folded half-page size, 4-page papers at the running speed of 48,000 per hour, 6 or 8 page papers at 24,000 per hour, and 12 or 16 page papers at 12,000 per hour. (5) Triple stereotype perfecting machine, delivering, folded half-page size, 4, 6, 8, 10, or 12 page papers at the running speed of 24,000 per hour, and 16, 20, or 24 page papers at 12,000 per hour. (6) Double stereotype insetting machine, which delivers papers, folded half-page size, with the supplements pasted in, if desired, at the running speed of 24,000 4, 6, 8, 10, or 12 page papers per hour, and 12,000 16, 20, or 24 page papers per hour. (7) Double stereotype insetting machine with two folders, delivering 4 or 6 page papers, folded halfpage size, at the running speed of 48,000 per hour, 8, 10, 12, or 14 page papers at 24,000 per hour, and 16, 20, or 24 page papers at 12,000 per hour. (8) Quadruple stereotype insetting machine with two folders delivering 4, 6, or 8 page papers, folded half-page size, at the running speed of 48,000 per hour, 10, 12, 14, or 16 page papers at 24,000 per hour, and 20 or 24 page papers at 12,000 per hour. (9) Sextuple stereotype insetting machine with three folders, delivering, folded half-page size, 4, 6, or 8 page papers at the running speed of 72,000 per hour, 10 or 12 page papers at 48,000 per hour, 16-page papers at 36,000 per hour, and 14, 20, or 24 page papers at 24,000 per hour. (10) Octuple stereotype insetting machine with four folders, delivering, folded halfpage size, 4, 6, or 8 page papers at the running speed of 96,000 per hour, 10-page papers at 72,000 per hour, 12-page

papers at 60,000 per hour, 14 or 16 page papers at 48,000 per hour, 18-page papers at 42,000 per hour, 20-page papers at 36,000 per hour, and 24-page papers at 24,000 per hour. The Methodist Book Concern's printing and folding machine made by R. Hoe & Co. is the first combination of mechanism capable of producing their Christian Advocate, a paper of 16 pages, cut at the head, pasted and delivered, folded either half or quarter page size at will, or, when desired, to print and deliver, in suitable form for trimming, a variety of other products in pamphlet form, consisting of 16, 32, or 64 pages, such as are published by this well-known house for Sunday-schools, etc. The web of paper from a large roll is fed to the impression cylinder by an automatic mechanism which insures a uniform tension, and after being printed on one side passes from the impression cylinder around a "transferrer" and returns to the opposite end of the same impression cylinder, reversed, so that both sides are printed by the same form-carrying cylinder, whence it passes to the pasting, folding, and delivering machine, which divides the broad printed web, brings the two webs together, cuts the two-ply web into sections, collects these sections one upon the other, folds them together, and sends them to either the mail or the carrier's delivery end of the machine, as the proper adjustment may decide, where they are re ceived upon carrying belts and presented for delivery, all of which is accomplished by rotary mechanism, and at a very high rate of speed. See TYPE-SETTING MACHINES.

Prior, (MATTHEW,) an Eng. poet, b. in London 1664. After 1688 P. was introduced to court by the Earl of Dorset, and was appointed secretary to the embassy which was sent to The Hague in 1690. At the age of 57 he died at the seat of the Earl of Oxford, 1721. A monument was erected to him in Westminster Abbey.

Pris'cian, surnamed CÆSARIENSIS, either because he was born or educated in the town of Cæsarea, is, perhaps, in point of reputation, the first of Latin grammarians, though one of the last in point of time. He belongs to the middle of the 5th c., if he is not even considerably later, for he is mentioned by Paulus Diaconus as a contemporary of Cassiodorus, (468-562 A.D.)

Priscillian, the author, or rather the chief propagator in Spain during the latter part of the 4th c., of the doctrines professed by the sect known from his name as Priscillianists. His doctrine was substantially that of the Manichæans. By an appeal to the usurper Maximus, at Treves, Ithacius caused P. and several of his followers to be brought to trial and put to death in 385; a proceeding which was regarded with so much abhorrence by St. Martin of Tours, St. Ambrose, and other bishops that they separated from the communion of Ithacius.

Prism, in Geom., a solid figure which can be most easily conceived of if we imagine a number of plane figures, exactly similar in form and size, to be cut out of paper or any thin plate, and piled one above the other, and then the whole pile to become one body. It. will thus be seen that the top and bottom of the P. are similar, equal, and parallel to each other, and that the sides are plane figures, rectangular if the P. be "right," but under all circumstances the sides of a P. must be parallelograms. The top and bottom faces may be either triangles, squares, parallelograms, or quadrilaterals of any sort, or figures of 5, 6, 7, etc., sides, provided only both are alike; and the number of sides in the plane figure which forms the top or bottom, of course, determines the number of faces of the P. P., in Optics, is a triangular P. of glass or other transparent substance, its two ends being isosceles triangles, and having most frequently a very acute vertical angle, which gives the P. the appearance of a long wedge. Pris'matic Colors, the seven colors into which light is resolved when passed through a prism; primary colors. Pris'moid, a frustrum of a wedge, resembling a prism. Its volume equals the sum of its parallel bases plus four times the section midway between the bases multiplied by one sixth of the altitude.

Pris'on, originally a place of detention rather than one of punishment. Debtors and political offenders were thus detained until the payment of dues by the former or the trial of the latter. The history of Ps. throughout the ages shows a sad story of neglect of sanitary rules, unnecessary cruelty, and abuse of arbitrary power. The introduction of Instruments of torture, with the idea of drawing forth confessions, gradually transformed Ps. into places of punishment, finally of execution. John Howard, the philanthropist, devoted his life to the amelioration of the physical and moral condition of the Ps. and jails of England and the Con

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tinent, but it is only within a very recent period that the reformed system of P. discipline, compulsory labor, sanitary regulations, with moral and religious influences, have been adopted. The statistics of the various State Ps. and county penitentiaries of the U. S. show a vast improvement where the enlightened plans of this nature have been adopted. The jails, however, throughout the country are in need of a radical reform. Of late the term P. discipline has obtained a new meaning in England, having been used to express not merely the practice of ruling Ps., but the science of properly ruling them. It has gone even further, and sometimes has been used to express the principles of penal administration, or the philosophy and practice of punishment. This has arisen from the circumstance that gradually other punishments have been dropped, and detention within edifices and the grounds attached to them has become almost the only method of punishment for crimes. Torture, exposure in the pillory, and other like dedications of the offender to public vengeance have been long abandoned as barbarous. Death punishment has been much narrowed in its application, and transportation, apart from any question as to its effectiveness, has been rendered impracticable, except within a very narrow compass. We get nothing from the practice of the times anterior to Christianity, nor yet from that of the Middle Ages, to help us in estimating the modern systems of P. discipline. They are a development of civilization, and, contradictory as it may seem to say so, of personal liberty. Hence we have no criminal law, properly speaking, coming down to us from antiquity. The corpus juris, so full of minute regulations in all matters of civic rights, has very little criminal law, because the criminals became slaves and ceased to be objects of the attention of the law. The tendency lately has been to regulate P. discipline with extreme The public sometimes complain that too much pains is bestowed upon it, that criminals are not worthy of having clean, well-ventilated apartments, wholesome food, skillful medical attendance, industrial training, and education as they now have in this country. There are many arguments in favor of criminals being so treated, and the objections urged against such treatment are held by those who are best acquainted with the subject to be invalid; for it has never been maintained by any one that a course of crime has been commenced and pursued for the purpose of enjoying the advantages of imprisonment. The system now received is that of separation, so far as it is practicable. Two other systems were tried-the silent system and the solitary system. The former imposed entire silence among the prisoners even when assembled together; the latter endeavored to accomplish their complete isolation from the sight of or communication with their race. By the separate system the criminals are prohibited from communicating with each other; but they are visited by various persons with whom intercourse is more likely to elevate than to debase-as chaplains, teachers, Scripture readers, the superior officers of the P., and those who have the external control over it.

care.