Page:Encyclopædia Britannica, Ninth Edition, v. 18.djvu/757

P E W P F E 725 useful citizen of Augsburg, remembered for his services to the new learning. He was one of the first to publish Roman inscriptions (see vol. xiii. p. 124), and his name remains associated with the famous Tabula Peutingeriana (see MAPS, vol. xv. p. 517), which was in his hands when he died, and was found again among his MSS. in 1714. This important Roman itinerary table was first published as a Avhole by Scheyb (Vienna, 1753) ; the most elaborate edition is by Desjardins (Paris, 1869 and following years). PEWTER l is a generic term for a variety of alloys, which all agree in this, that tin forms the predominating com ponent. The finest pewter (sometimes called " tin and temper ") is simply tin hardened by the addition of a trifle of copper. Ordinary pewter is tin alloyed with lead, which latter ingredient i.s added chiefly on account of its cheapness, and therefore often in excessive proportion. The law of France restricts the percentage of lead to 16 5, with a toleration of 1 5 per cent, of error, an alloy of this or a higher degree of richness in tin being, according to an old investigation by Vauquelin, as proof against sour wine or vinegar as pure tin is. Higher percentages of lead are dangerous, and besides spoil the appearance of the alloy. The composition of an alloy containing only these two components can be ascertained approximately by deter mining the specific gravity (see METALS, vol. xvi. p. 67 sq.). Plate peivter is a hard variety much used for plates and dishes ; a good quality is composed of 100 parts of tin, 8 of antimony, 2 of bismuth, and 2 of copper. Closely allied to it is the silver- white alloy called " Britannia metal," which is much used in Great Britain for the making of tea pots more especially. To give an idea of its very variable composition the following two analyses may be quoted : Tin 857 Antimony 10 - 4 Copper I O Zinc .. ..2 9 100-0 81-9 16-2 o-o 1-9 100-0 Pewter wares are shaped chiefly in three ways. Measures and spoons are cast in moulds of brass made of two closely- fitting but detachable halves, the surface of the mould being powdered over with sandarach, or painted over with white of egg or oil, before use to prevent adhesion. Plates and dishes are made preferably by hammering. In large establishments milk -jugs and similar articles are often produced by "spinning," i.e., by pressing a flat plate of pewter against a rapidly- revolving blunt tool, and thus raising it into the desired shape. (Cf. LEAD, vol. xiv. p. 378.) PFAFF, CHRISTIAN HEINRICH (1773-1852), chemist and physicist, younger brother of J. F. Pfaff noticed below, took his degree as doctor of medicine at Stuttgart in 1793. He travelled with a noble family as physician, and practised for a time at Heidenheim ; but he afterwards became pro fessor (extraordinary in 1797, ordinary in 1801) of medi cine, physics, and chemistry at the university of Kiel. He was a most prolific author of memoirs on sanitary and medical, and especially on chemical and physical, subjects. His work in chemistry was chiefly analytical and mineral- ogical. In physics he was distinguished as one of the earlier experimenters with the voltaic current, and had a considerable share in the experimental investigation of its properties. He also made important researches on the carrying power of magnets, more particularly on the effect of the extent of the attracting surface. Comparatively few of his memoirs are now quoted, owing to the fact that none of his results contained any capital discovery ; never theless he deserves to be remembered as one of the ener getic workmen who aided in raising the stately pile of modern experimental science. 1 Old Fr. peutre ; Ital. peltro ; comp. Eng. spelter. PFAFF, JOHANN FRIEDRICH (1765-1825), German mathematician, was born on 22d December 1765 at Stutt gart. He received his early education at the Carlsschule, where Schiller, afterwards his life-long friend, was a school- companion. His mathematical capacity was early noticed ; and after leaving school he pursued his studies in that department at Gottingen under Kastner, author of a History of Mathematics; and in 1787 he went to Berlin and studied practical astronomy under Bode. In 1788 Pfaff became professor of mathematics in Helmstadt, and so continued until that university was abolished in 1810. From that time till his death (20th April 1825) he held the chair of mathematics at Halle. PfafFs researches bore chiefly on the theory of series, to which he applied the methods of the so-called Combinatorial School of German mathematicians, and on the solution of differential equa tions. His two principal works are Disquisitiones analytical maxime ad calculum integralem et doctrinam serierum pertinentes (4to, vol. i., Helmstadt, 1797) and " Methodus generalis, aequationes differentiarum particularum, nee non tequationes differentiales vulgares, utrasque primi ordinis inter quotcumque variabiles, complete integrand! " in Abh. d. Berl. Acad. (1814-15). The former work con tains Pfaffs discussion of the equation (a + bx n ] x 2 d 2 y/dx 2 + (c + ex n )xdy/dx + (f+gx n )y = X, which generally bears his name, but which had originally been treated in a less complete manner by Euler. The latter work contains an important addition to the theory of partial differential equations as it had been left by Lagrange. An interesting review of Pfaffs memoir was published by Gauss in the Gottingen Gelchrte Anzcigcn for 1815 (repu Wished in vol. iv. of his complete works). For fuller details regarding Pfaff and his work, consult Gerhardt, Gcschichte dcr Mathematik in Deutschland (Munich, 1877, p. 198), and Pfaffs correspondence, edited by C. H. Pfaff. Another brother of this family, JOHANN "VViLHELM ANDREAS PFAFF (1774-1835), was professor of pure and applied mathematics successively at Dorpat, Nuremberg, Wiirzburg, and Erlangen. PFALZBURG, a town of German Lorraine, lies high on the west slopes of the Vosges, 25 miles to the north-north west of Strasburg. In 1880 it contained 3379 (mainly Roman Catholic) inhabitants. The principality of Pfalz- burg, originally a part of Luxemburg, afterwards belonged in turn to the bishop of Metz, the bishop of Strasburg, and the duke of Lorraine, and passed into the possession of France in 1661. The town was of importance as com manding the passes of the Vosges, and was strongly forti fied by Vauban in 1681. The works resisted the Germans for four months in 1870, but have since been razed. PFEIFFER, FRANZ (1815-1868), an eminent writer on mediaeval German literature and on old forms of the German language, was born at Solothurn on the 27th of February 1815. Having studied at the university of Munich, he went to Stuttgart, where in 1846 he became librarian at the royal public library. In 1857, having established his fame as one of the foremost authorities on his special subject, he was appointed professor of German literature and language at the university of Vienna ; and in 1860 he was made a member of the Imperial Academy of Sciences. He died on the 29th of May 1868. As an editor of mediaeval literature Pfeiffer was unsurpassed among the scholars of his day, and by his work in this department he did much to foster the critical study of writers who before his time were known only to specialists. Among the many writings edited by him may be mentioned the works of the German mystics of the 14th century, the Buck dcr Natur of Conrad of Megenberg, the Predigten of Berthold of Ratisbon, the Eddstcin of Ulrich Boner, the Barlaam und Josaphat of Rudolf of Ems, and the poems of Walther von der Vogelweide. Of his independent writ ings the most important are Zur dcutschcn LitcraturgcscMchte, Uebcr Wesen und Bildung der hqfischcn Sprache in mittelhoch- dcutscher Zeit, Der Dichtcr dcs Nibdungenliedcs, Forschung und Kritik auf dem Gebicte des deutschen Altcrthums, and Altdcutsches Uebungsbuch. Pfeiffer s style is clear and vigorous, and on every