Porcelain. See POTTERY.

Porcelain, Japanese. The exhibit of rare porcelain at the Centennial Exposition, 1876, brought to light many interesting facts concerning the native mineral materials from which J. P. goods are made, and their skill in the manufacture. Only one of the Idzumi-Tama minerals examined bears the least resemblance to clay. The peculiar Japanese kilns are always built on the slope of a hill, 4 to 20 in a set. Ideas of higher ceramic art were imported into Japan from China and Corea about 300 yrs. ago. Gorodayu Shonshi first made porcelain 1580. The "Satsuma " ware was originated by Corean prisoners about 1592.

Porch, a building forming an inclosure or protection for a doorway. Every one knows how much this beautiful feature is now used, and how efficient it is as a protection from the wind and weather. In Elizabethan and mediæval architecture the P. was also very common in domestic architecture. In churches it was almost universal

in England. In France many splendid Ps. or portals remain, and they are among the most beautiful specimens of mediaval art. In England wooden Ps. of picturesque structure,

are very common in ancient parish churches.

Porch.

Por cher, (FRANCIS PEYRE, M.D.,) a distinguished physician of S. C., editor of several medical books and reviews; Prof. of Materia Medica and Clinical Medicine in South Carolina State Medical Coll.; b. 1824.

Porcu'na, an ancient and picturesque Span. town, in the prov. of Jaen; pop. 7,645.

Porcupine, a genus of mammalia, of the order Rodentia, and family Hystricide. This family is remarkably characterized by an armature of spines, which, like those of the hedgehogs, are, as to their structure, merely thick and strong hairs. The Hystricide are plantigrade; the fore feet have four toes and a rudimentary thumb, the hind feet have five toes. Their general aspect is heavy and pig-like, and they have a grunting voice. The muzzle is broad and blunt; the ears short and rounded; the incisors smooth and large, two above and two below; the molars eight above and eight below. The

Porcupine.

name P. is derived from the Lat. porcus, " swine," and spina, a thorn." The Common P. is a native of the S. of Europe, of many parts of Asia, and of the most parts of Africa. The spines or quills of the P. are used for various purposes, and have a certain commercial value. It is chiefly sought on account of them, although its flesh is eaten, and was brought to the market of ancient Rome.

Pordeno'ne, a town of Venetia, Italy, in the prov. of Udine. The site is supposed to be that of the Portus Naonis of the Romans. Pop. 8,269.

Pore, an opening or narrow passage in any solid substance, more especially in the glands and skins of animals. They serve the purpose of throwing off the waste or effete portions

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of the body, chiefly as perspiration. There are about 7,000,000 Ps. in an ordinary sized man. Each P. is about in. in 1.; 8,528 Ps. have been counted on 1 sq. in. of the palm of the hand. There are 175,000 in. of Ps.-i. c., 145,833 ft., 48,600 yds., nearly 28 m. of this drainage in a human body.

Por'gy, an Amer. fish, common to New York and its vicinity, as well as to other points of the Amer. coast, family Sparrida. It is a very abundant, cheap fish, and is much prized for its savory flesh.

Porif'era, or Sponges, many-celled animals with tissues arranged in three layers, without a true digestive cavity; the soft parts supported usually by calcareous or siliceous spicules. The body-mass is permeated by microscopic ciliated passages opening into minute chambers lined by ciliated monad-like cells. There is no true mouth-opening, but usually an irregular system of inhalent pores opening into the digestive cell-lined chambers or passages through which the food is introduced in currents of sea-water. Sponges grow from eggs. Of the marketable sponges there are six species, with numerous varieties. They are available for use in bathing from being simply fibrous, having no hard, siliceous spicules. The Mediterranean sponges are the best, while our West Indian kinds are coarser and less durable.

Po'rism, a kind of geometric proposition in high favor among ancient Greek mathematicians, but of which the notices that have come down to us are so few and meager that till lately mathematicians were not agreed about what a P. really was. As defined by Playfair, "a P. is a proposition affirming the possibility of finding such conditions as will render a certain problem indeterminate, or capable of innumerable solutions."

Pork, the flesh of swine, forms a very large portion of the animal food of most nations, although it is not the most nutritive, as will be seen by the following comparison of the four principal kinds of flesh-food:

It has qualities, however, which especially fit it for man's use; its fatness makes it a very heat-giving food for cold and temperate climates, while it surpasses all other kinds of animal

food in the ease with which it may be preserved by salting and drying. Hence the trade in P. is considerable in all countries where it is used, but especially so in Am. and Great Britain, particularly the former country, where vast quantities are cured for the supply of ships, for home use, and for exportation.

Poros'ity. By this term we express the experimental fact that no kind of matter completely fills the space it occupies; in other words, that all bodies are-full of minute cavities or interstices, such as are illustrated on a large scale by a sponge. On the atomic theory, it is obvious that this must be the case if the atoms of matter are spherical, or, indeed, if they have any form save one or two special ones, such as cubes or rhombic dodecahedrons. It is commonly asserted that all bodies must be porous, because they are compressible; but this is a great mistake, since we have no reason to believe that matter is not per se compressible, independently of the existence of interstices.

Porphyr'ius, one of that series of ancient philosophers to whom is due the reformation of the Greek philosophy known as Neoplatonism, was probably b. at Batanea, in Syria, in the yr. 233 A.D. His original name was Malchus, the Greek form of the Syro-Phoenician Melech, or king. The name by which he is known in history is P. He is said by Socrates the historian, and by St. Augustine, to have been originally a Christian. It was at Rome, however, whither he repaired soon after 260, that he entered upon what must be regarded as, historically considered, the career of his life. Here he became a scholar of the Neoplatonist Plotinus. After six yrs.' residence