600 P O T P O T an extensive edifice in the Italian style, containing numer ous pictures and other works of art. The park also includes the Charlottenhof, a reproduction of a Pompeian villa. At the west end of the park stands the New Palace, a huge brick edifice 375 feet in length, erected by Frederick the Great at enormous expense in 1763-69; and now occu pied by the crown prince of Germany. It contains other reminiscences of Frederick and Voltaire, a few pictures by ancient masters, a theatre, and a large hall gorgeously decorated with shells and minerals. The spacious build ings at the back are devoted to the "Lehrbataillon," a battalion of infantry composed of draughts from differ ent regiments trained here to ensure uniformity of drill throughout the army. To the north of Potsdam lies a small Russian village, established in 1826 to accommodate the Russian singers attached to the Prussian guards. A little to the east of it is the New Garden, containing the Marble Palace. The list of Potsdam palaces may be closed with two situated on the left bank of the Havel one at Glienicke and the other on the hill of Babelsberg. The latter, a picturesque building in the English Gothic style, in the midst of a park also in the English taste, is the summer residence of the present emperor of Germany. Potsdam was originally a Slavonic fishing-village named Potsdu- pimi, and is first mentioned in a document of 993. It did not, however, attain any importance until the Great Elector established a park and palace here about 1660 ; and even at the close of his reign it only contained 3000 inhabitants. Frederick William I. (1688-1740) greatly enlarged Potsdam, and his stiff military tastes are reflected in the monotonous uniformity of the streets. Frederick the Great willingly continued his father s work, and is the real creator of the modern splendour of the town, of which his memory may be said to form the predominant interest. His successors have each contributed his quota towards the embellishment and extension of the town. POTTER, JOHN (c. 1674-1747), archbishop of Canter bury, was the son of a linen-draper at Wakefield, York shire, and was born about 1674. At the age of fourteen he entered University College, Oxford, and in 1693 he published, at the suggestion of the master of his college, various readings and notes on Plutarch s De audiendis poetis and Basil s Oratio ad juvenes. In 1694 he became a fellow of Lincoln College, and in 1697 his edition of Lycophron appeared. It was followed by his Archseologia Grseca (2 vols. 8vo, 1697-99), once a very popular work. A reprint of his Lycophron in 1702 was dedicated to Grsevius, and the Antiquities was afterwards published in Latin in the Thesaurus of Gronovius. In 1704 he be came chaplain to Archbishop Tenison, and shortly after wards was made chaplain- in r ordinary to Queen Anne, From 1708 he was regius professor of divinity and canon of Christ Church, Oxford; and from 1715 he was bishop of Oxford. In the latter year appeared his edition of Clemens Alexandrinus (frequently reprinted and still valued). In 1707 he published a Discourse on Church Government, and he took a prominent part in the controversy with Hoadly, bishop of Bangor, being complimented by that author as the antagonist of whom he was most afraid. In January 1737 Potter was unexpectedly appointed to succeed Wake in the see of Canterbury. His primacy was in no way re markable, but had the effect of checking the movement for revision of the formularies and confessions of the church and of the subscription to them. He died on 10th October 1747. His Theological Works, consisting of sermons, charges, divinity lectures, and the Discourse on Church Government, were published in 3 vols. 8vo, in 1753. POTTER, PAUL (1625-1654), animal painter, was born at Enkhuizen, Holland, in 1625. He was instructed in art by his father, Peter Potter, a landscape and figure painter of some merit, and by the time he had attained his fifteenth year his productions Avere already much esteemed. At the age of twenty he settled at The Hague, and there married in 1650. He was patronized by Maurice, prince of Orange, for whom he painted the life-size picture of the Young Bull, now one of the most celebrated works in the gallery of The Hague. In 1652 he was induced by Burgomaster Tulk of Amsterdam to remove to that city. The constitution of the painter seems to have been feeble, and his health suffered from the unremitting diligence with which he pursued his art. He died in 1654 at the early age of twenty-nine. His paintings are generally on a small scale ; his animals are de signed with a careful accuracy which bears witness to the artist s close and constant study from nature ; while the landscape back grounds are introduced with spirit and appropriateness. His colour is clear and transparent, his execution firm and finished without being laboured. He executed a series of some twenty etchings, mainly of animals, which are simple and direct in method and handling. Here, as in painting, his precocity was remarkable ; his large plate of the Herdsman, produced when he was only eighteen, and that of the Shepherd, which dates from the following year, show him at his best as an accomplished master of the point. Plate V. n^HE word "pottery" (Fr. poterie) in its widest sense I includes all objects made of clay, moulded into form while in a moist plastic state, and then hardened by fire. Clay, the most widely spread and abundant of all mineral substances, consists essentially of a hydrated sili cate of alumina (see vol. x. p. 237), admixed, however, in almost all cases with various impurities. Thus it usually contains a considerable proportion of free silica, lime, and oxides of iron, its colour chiefly depending on the last in gredient. The white kaolin clays (see KAOLIN) used in the manufacture of porcelain are the purest ; they consist of silicate of alumina, with 5 to 7 per cent, of potash, and only traces of lime, iron, and magnesia. The making of pottery depends on the chemical change that takes place when clay is heated in the fire ; the hydrated silicate of alumina becomes anhydrous, and, though the baked vessel can absorb mechanically a large quantity of water, the chemical state, and with it the hard ness of the vessel, remains unaltered. A well-baked piece of clay is the most durable of all manufactured substances. In preparing clay for the potter it is above all things necessary that it should be worked and beaten, with suffi cient water to make it plastic, into a perfectly homogeneous mass. Any inequalities cause an irregular expansion during the firing, and the pot cracks or flies to pieces. In early times the clay was prepared by being kneaded by the hands or trampled by the feet (see Isa. xli. 25) ; modern manu facturers prepare it on a larger scale by grinding it between mill-stones, and mixing it in a fluid state with an addi tional quantity of silica, lime, and other substances. During the process of firing all clays shrink in volume, partly through the loss of water and partly on account of in crease of density. What are called "fat" clays those, that is to say, which are very plastic and unctuous shrink very much, losing from one-third to one-fourth of their bulk ; they are also very liable to crack or twist during the firing. "Lean" clays those that have a large percentage of free silica shrink but little, and keep their form unaltered under the heat of the kiln ; they are not, however, so easy to mould into the required shape, and thus a certain com promise is frequently required. Lean and fat clays are mixed together, or silica (sand or ground and calcined flints) is added to a fat clay in sufficient quantity to enable
it to stand the firing. The same result may be attained