ic, typographic and stereographic. In rylographic printing, the writing is carved on wooden tables; they are then covered with ink, the paper is put upon them, and an impression is taken. This is the oldest mode of printing, and is still in use in China, Japan and Thibet. Typographic printing is that in which single letters or types are used, which are properly arranged, and then the work is printed. For a short time, carved letters were in use; but cast letters were soon introduced, and are still used. In stereographic printing, pages composed of many types are transformed, by casting, into plates, or tables, from which copies are printed. A mould of plaster is taken from a page of types, and from this the stereotype plates are obtained by casting. The Chinese, even in the reign of their emperor Wu-Wang, who lived about 1100 B. C., are said to have been well acquainted with xylographic printing; but the Japanese as sume the merit of the invention. In Thibet, also, according to the accounts of various travellers, this art has been exercised from time immemorial. Although it had been the custom, for thousands of years, to make impressions with seals on wax, which might have easily led to the invention of the art of printing, Guttenberg first made this discovery, about three centuries and a half ago; for it may justly be questioned, whether the Europeans had then any knowledge of the art of printing among the Chinese, although it is not to be denied, that, before the time of Guttenberg, and even in 1423, the art of cutting images on wood, with a few lines of text, was well known. Three cities contend for the honor of the invention of typographical printing-Harlem, Strasburg and Mentz. The people of Harlem maintain that their citizen Laurence Jansoen, under the name of Coster (i. e. sacristan in the great parochial church at Harlem), as early as 1430, invented the art of cutting on wooden tables. But he did not stop here; and there are many of Coster's impressions, as Scheltema and Könings have tried to prove, as late as the year 1823, made with movable types of wood, and afterwards of lead and tin. If the invention of the art of printing is thus due to the Dutch (Van Hultem, a learned Dutch writer, is opposed to this opinion), the invention of the art in Mentz still ought to be considered as independent of that in Harlem; for the account that Coster was robbed of his types by his assistant John, who fled through Amsterdam and Co

logne to Mentz, and there printed, in 1442, Alexandri Galli Doctrinale and Petri Hispani Tractatus, is without foundation. The people of Strasburg ascribe this invention to Guttenberg, in Strasburg. The people of Mentz, on the contrary, maintain that Guttenberg invented typographical printing, not in Strasburg, but in Mentz. The truth is, that Guttenberg (q. v.) conceived the first idea of his invention, and made a few experiments of it at Strasburg, but first brought it to perfection, with the aid of Peter Schöffer, in Mentz. It is proved that Guttenberg, as early as 1436, when he was still at Strasburg, had his printing instruments, and, the same year, made some trials with a printing press. But, dissatisfied with the slow process of the xylographic method, he began to consider whether he might not print with single letters, and use the same letters more than once. This led him to the invention of movable letters, which he must have used earlier than 1442, for, in this year, separate letters were in use. In 1445, Guttenberg returned to his native city, Mentz; and with 1449 begins the period of the completion of the art of printing. Guttenberg, in the course of this year, connected himself with a rich citizen in Mentz, named John Fust (Faustus), who carried on the business of founding, in company with Peter Schöffer, of Gronsheim. Faustus, soon after (probably in 1453), entered into a copartnership with this Schöffer, an inventive genius, who now became the true perfecter of the art of printing. Guttenberg, indeed, had invented movable letters, and made them first of wood, then of lead, and at last of tin. But the art of printing continued to be very difficult and expensive, till the metallic letters cast by John Faustus, or Peter Schöffer, and other improvements, were invented. The oldest work, of any considerable size, printed in Mentz, with cast letters, by Guttenberg, Faustus and Schöffer, finished about 1455, is Guttenberg's Latin Bible, which is called, also, the Fortytwo-lined Bible, because in every full column it has forty-two lines. Faustus, having separated from Guttenberg, in 1456, and, by means of a loan of 2020 florins, having obtained his printing press for his own use, undertook, in connexion with Peter Schöffer, greater typographical works, in which the art was carried to higher perfection. Faustus was particularly engaged in the printing of the Latin and German Bible, by the copying of which the monks had hitherto gained

considerable sums. As they could not understand this astonishing multiplication of the printed copies, and therefore ascribed it to some inspiration of Satan, he became involved in a violent quarrel with them. He went to Paris with his Bibles (the first copies of which, bearing date, were printed in 1462), for the purpose of selling them there. Being obliged to leave the city in haste, on account of the persecutions of the German monks, this probably gave rise to the well-known tradition, that the devil had carried him off. In 1466, Faustus made a second journey to Paris, and died there of the plague; upon which P. Schöffer continued the printing business alone, at Mentz. After the separation of Guttenberg and Faustus, the former had found means to procure a new printing press, and had struck off many works, of which the most remarkable is the Astrological and Medical Calendar (in folio, 1457), considered the first known work printed with the date annexed. As the letters of this Calendar are entirely different from those with which Faustus and Schöffer printed, it is confidently inferred that this Calendar was printed at the press of Guttenberg. After 1462, many workmen went from Mentz, and established presses in Germany and in foreign countries, first in Italy, then in France, the king of which, at that time, was the first prince that in terested himself in the new art. Besides Faustus, Schöffer and Guttenberg, one Albert Pfister became acquainted (it is not known by what means) with the art. Soon after 1450, he also printed a Bible. As the art of printing began with the impression of whole blocks, it has come to the same point again in its progress towards perfection, viz. by the introduction of stereotype plates. The art of printing, as every one knows, was greatly advanced by the invention of movable letters; but on this very account, as often as a book is reprinted, new errors creep in; and, in printing, the letters sometimes stick to the balls, and are drawn out with them, whence new errors of the press are made, because the printer does not always set them again correctly. These imperfections are particularly felt in books consisting of tables of numbers. Firmin Didot, son of Francis Ambrose Didot, when engaged in printing the logarithmic tables of Callet, invented a method to prevent all errors, by causing the pages, composed of movable letters and figures, and accurately corrected, to be cast into entire plates, which might be moved

without displacing a single letter. By this contrivance, the displacement of the letters, and new errors of the press during the printing, are made impossible. If an error is afterwards discovered, the plate is pierced, the wrong letter taken out, and the right one put in, and it is soldered again, so that the plate may be thus made perfectly correct. Didot called these letters, thus united, stereotype, from the Greek oreptos (firm, standing firm) and ru (figure, form). He printed Callet's abovementioned logarithmic and trigonometrical tables with them in 1795. The invention of stereotype printing does not properly belong to Didot, but is ascribed to the Dutch. More than a hundred years since, it was in use among them. The inventor of it is said to have been J. van der Mey, father of the well-known painter of the same name, who resided at Leyden towards the end of the seventeenth century. He prepared and cast immovable forms or plates for a Dutch Bible in quar to, of which many thousand copies were struck off. The plates of this Bible are still in the hands of the booksellers S. & J. Luchtmans, in Leyden. At the death of Mey, the art of making fixed types was lost again in Holland; at least, no further use was made of it, because the method was too expensive. A Scotchman, als by the name of Ged, at the beginning of the eighteenth century, invented the art of printing from cast plates, and struck off an edition of Sallust, with types soldered together. Hence it appears that Didot had predecessors in stereotype or stereographic printing. He, however, greatly improved the art. His improved contrivance was as follows: He took movable letters, differing from the common ones only by being somewhat shorter. and of a harder substance. These were set in the usual way; the proof sheets were then printed and corrected, till the whole copy was as free from errors s possible. Then every page set with thes hard letters was pressed upon a plate of properly prepared metal. These plates served as matrices for whole pages; and the letters of the hard substance, mentioned above, might now be separated from each other, set anew, and used to form other matrice-plates. A page which served for a matrix was pressed up melted type-metal, which, hardening in mediately, served for printing. In printic the plates, or pages, were set upon plates of brass, which took the place of a for and were necessary to support the whole for these stereotype pages or columas

being very thin, could otherwise hardly bear the violence of printing. The process of stereotyping, at present, is simple. A page of any work proposed to be stereotyped, is set up in the usual manner, with movable types. From this page, when corrected, a mould in plaster is taken off, and from this mould a plate of type metal is cast, having all the characters in relief, and being a fac-simile of the original page. From this plate the printing is executed, and there must be, of course, as many plates cast as there are pages in the book to be printed. The plaster used for forming the moulds is pulverized gypsum, dried by heat, and mixed with water, to which is added a little whiting, to diminish the tendency of the plaster to shrink and crack. After the form of types has been slightly oiled, and surrounded with a brass frame, fluid plaster is applied over the surface, with a brush or roller, so as to fill every cavity of the letters. A quantity of plaster, mixed with water to the consistence of cream, is then poured on the type, and the superfluous part scraped off. When the plaster has become hard, it is lifted off by the frame, and detached from it. It is then baked to dryness in an oven, and, when quite hot, it is placed in an iron box, or casting-pot, which has also been heated in an oven. The box is now plunged into a large pot of melted type-metal, and kept about ten minutes under the surface, in order that the weight of the metal may force it into all the finer parts of the letters. The whole is then cooled, the mould is broken and washed off, and the back of the plate turned smooth in a lathe, or planed by a machine. For typographical beauty, the most distinguished printers are Baskerville in England; Didot and Crapelet in France; Bodoni in Italy; Ibarra in Spain; and Breitkopf, Göschen and Tauchnitz in Germany. Next to types, the chief instrument used in this art is the printing press. The ink is first applied over the whole surface of the types; the paper, previously moistened, is then laid down upon them; the whole is passed under the press, and the paper, being brought into forcible contact with the types, receives from their surface the ink necessary for a distinct impression. Printer's ink (q. v.) is composed chiefly of lampblack and oil, inspissated by boiling and burning. Oil is necessary that the ink may not dry during the operation, and it is reduced by boiling to prevent it from spreading on the paper. It is applied to the types by large elastic balls,

made of leather and stuffed with wool, or by elastic rollers. Guttenberg printed, at first, with writing ink, and afterwards used lampblack. About 1450, or somewhat later, Faust and Schöffer invented printer's ink. The common old printing press derives its power from a screw, which is turned by a lever, and acts perpendicularly on the platten, or level part, which transmits the pressure. Various improvements have been made in the printing press, by lord Stanhope and other inventors, in most of which a cast iron frame is substituted for a wooden one, being more inflexible; and a combination of levers is used, so arranged as to cause the platten to descend with decreasing rapidity, and consequently with increasing force, till it exerts the greatest power at the moment of contact of the paper with the types. Before the press was invented, impressions were taken from the wooden tables by means of a rubber of horn. Guttenberg invented the press. In a Strasburg document, it is proved that this apparatus was in use as early as 1436. In France, on the other hand, there were no presses in 1458; for during that year Charles VII sent a man to Strasburg, to learn the art of printing there. Leonard (John) Danner, who died 1585, first introduced brazen spindles into printing, in 1550, at Nuremberg. Printing by machinery had its origin within the present century. It has produced a very great improvement in the expedition with which work is executed, and is now extensively applied to the printing of newspapers, and even of books. Various machines are already introduced into use, most of which perform the processes of inking the types, conveying the paper, and giving the impression. For distributing the ink on the types, elastic cylinders are employed, called inkingrollers, made of a composition of glue and treacle, which combines the properties of smoothness, elasticity, and sufficient durability. These transmit the ink to the types by rolling over their surface. The impression is performed, in most of the English machines, by large cylinders, which revolve upon the types, having the sheet of paper confined to their surface by bands of tape. The types are arranged in some machines in the common flat form; in others, the characters are placed in a convex form, upon the surface of cylinders. To produce the latter effect, Mr. Nicholson proposed to cast the body of the types with a tapering or wedge form, like the stones of an arch; but Mr. Cowper has produced the same result

for classical literature, and attracted the notice of the earl of Dorset (see Sackville), who enabled him to enter himself, in 1682, at St. John's college, Cambridge, where he proceeded B. A. in 1686, and was shortly after chosen fellow. At college he contracted an intimacy with Charles Montagu, afterwards earl of Halifax, in concert with whom, in 1688, he composed the Country Mouse and City Mouse-a parody on Dryden's Hind and Panther. In 1690, he was introduced at court by the earl of Dorset, at whose recommendation he was appointed secretary to the English plenipotentiaries at the Hague. With this post he also held the title of gentleman of the king's bed-chamber; and he presented an ode to king William in 1695, on the death of queen Mary; and soon after displayed his humorous vein in a parody of Boileau's ode on the taking of Namur, when it was recaptured by William. In 1697, he was nominated secretary to the commissioners for the treaty of Ryswick; and, on his return from that employment, was made secretary to the lord-lieutenant of Ireland. He was afterwards secretary to the earls of Portland and Jersey, successively ambassadors to France. At length he was made under-secretary of state, and, while holding that office, was sent to France to assist in the partition treaty. In 1701, he succeeded Locke as a commissioner at the board of trade, but soon after deserted the whigs and joined the tories, for which no satisfactory reasons have been assigned. At the beginning of the reign of Anne, he published a volume of poems, and took some share in the Examiner. When the tories again obtained the ascendency, he was employed in secretly negotiating at Paris the terms of the treaty of Utrecht. (q. v.) He remained in France, with the appointment of ambassador, and, after the departure of the duke of Shrewsbury, in 1713, publicly assumed that character. On the accession of George I, he was recalled, and examined before the privy council in respect to his share in negotiating the treaty of Utrecht, and treated with great rigor for some time, although ultimately discharged without trial. Being without any provision for his declining years, except his fellowship, he again applied himself to poetry; and having finished his Solomon, he published his poems by subscription. The publication, being liberally encouraged by party zeal, produced a considerable sum, which was doubled by the earl of Oxford, at whose seat the author died, after a lingering illness, in 1721, in the fifty-eighth year of

his age. He was interred in Westminster abbey, under a monument, for which "last piece of human vanity," as he styles it in his will, he left the sum of £500. Prior seems to have made his way by wit and social qualities, rather than by moral or political endowments of a superior order. He is said to have always retained a taste for coarse intercourse and gross enjoyments. As a poet, his reputation has declined of late years, the humor in which he principally excels being overlooked on account of the character of his serious performances, which, although, as in his Solomon, and Henry and Emma, splendid and correct in diction, harmonious in versification, and copious in poetical imagery, fail in moving either the feelings or the fancy. The great art of Prior consists in telling a story with a degree of poetical ease and vivacity, which, perhaps, setting aside La Fontaine, has never been excelled. His Alma, a piece of philosophical pleasantry, exhibits a felicitous vein of humor; and for his lighter pieces he is now chiefly read. A History of his Own Times, compiled from his MSS., contains little from his pen, and is of small value. His poems were published in 1733, in 3 vols., 8vo., and are also in all the collections.

PRISCIAN. (See Philology.)

PRISM, in geometry, is a body, or solid, whose two ends are any plain figures which are parallel, equal and similar; and its sides, connecting those ends, are parallelograms. Hence every section parallel to the base is equal and similar to the base; and the prism may be considered as generated by the parallel motion of this plane figure. Prisms receive particular names, according to the figure of their bases; as a triangular prism, a square prism, a pentagonal prism, a hexagonal prism, and so on. And hence the denomination prism comprises also the cube and parallelopipedon, the former being a square prism, and the latter a rectangular one. And even a cylinder may be considered as a round prism, or one that has an infinite number of sides. Also a prism is said to be regular, or irregular, according as the figure of its end is a regular or an irregular polygon. The axis of a prism is the line conceived to be drawn lengthwise through the middle of it, connecting the centre of one end with that of the other end. Prisms, again, are either right or oblique. A right prism is that whose sides and its axis are perpendicular to its ends, like an upright tower; and an oblique prism is when the axis and sides are ob