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PYRENEES 389 PYRITES There are two large pyramids, with some hundred smaller ones. The base of the largest is 900 feet long, its height 160 feet. In anatomy, a conical bony eminence in the anterior wall of the tympanum of the ear. In geometry, a polyhedron bounded by a polygon, having any num- ber of sides, called the base, and by tri- angles meeting in a common point, called the vertex. Pyramids take different names according to the natures of their bases. They may be triangular, quad- rangular, etc., according as their bases are triangles, quadrilaterals, pentagons, etc. In botany, the American calumba or Indian lettuce, Frasera carolinensis. Pyramid pool ; A game played with 15 red balls and one white ball, the former being placed in a triangular form at a spot on the top of the table. The ob- ject of the players, who play in turn with the white ball, is to pocket as many red balls as possible. PYRENEES, an extensive mountain range in the S. of Europe, dividing France from Spain, and extending al- most in a straight line from St. Sebas- tian, on the Bay of Biscay, to Cape Creux, on the Mediterranean. Length 270 miles, with a breadth from 50 to 100 miles. The principal summits are Mount Perdu, which has an elevation of 10,994 feet; the Vignemale, 10,820 feet; and the Peak of Nethou, 11,168 feet. There are many passes; the total num- ber, including paths for pedestrians, ex- ceeds 50; but the carriage-roads hardly exceed five; and of these, the most fre- quented are from Jonquera to Perpignan on the E., and from St. Sebastian to St. Jean de Luz on the W., and from Pampe- luna to St. Jean Pied de Port. The passes in the interior are over very high ground; Pineda is 8,248 feet above the sea; Gavarnie, 7,654; Lavareze, 7,350; and Tourmalet, 7,143. The principal rivers rising in the Pyrenees are the Adour, Garonne, and Aude, flowing N., and the Llobregat, and numerous afflu- ents of the Ebro, flowing toward the S. PYRENEES, BASSES, a department in the S. W. corner of France, between the Landes and Spain, and having the Bay of Biscay on the W. ; area 2,977 square miles; pop. about 435,000. It is divided into the arrondissements of Pau, Oloron, Orthez, Bayonne, and Mauleon. Chief town, Pau. The department oc- cupies the N. slopes of the western Pyrenees. Agriculture is the principal industry; large herds of cattle and sheep are fed on the extensive pastures, and many swine in the wide forests. Of the numerous mineral springs the most im- portant are thos" of Biarritz, Eaux- Bonnes, and Eaux-Chaudes. The W. half of the department is the home of the Basques (q. v.). PYRENEES, HAUTES, a department of France lying E. of Basses-Pyrenees; a part of the old province of Gascony; area, 1,749 square miles; pop. about 205,- 000. As its name implies, it contains the loftiest summit of the Pyrenees (q. v.), and is divided into the three arron- dissements of Tarbes, Argeles, and Bapr- neres de Bigorre; chief town, Tarbes. The principal rivers are the Adour and the Gave de Pau. The well-cultivated and artificially watered lowlands yield good crops of cereals, leguminous plants, and fruits of every kind, including the grape. Cattle, sheep, and swine are reared. Marble and slate are quarried. In this department are the springs of St. Sauveur, Bagneres-de-Bigorre, Bar- reges, and Qauterets. PYRENEES-ORIENTALES, a S. de- partment of France; bounded on the E. by the Mediterranean and on the S. by the Pyrenees; area, 1,598 square miles; pop. about 213,000. It is divided into the three arrondissements of Perpignan, Prades, and Ceret. The chief town is Perpignan. Agriculture is extensively prosecuted, but wines constitute the wealth of the district, and include the red wines of Roussillon, the white musca- tel of Rivesaltes, and others. This de- partment takes the front rank as a pro- ducer of iron ore; granite, slate, and limestone are quarried. There are min- eral springs at Amelie-des-Bains, and elsewhere. PYRETHRUM, in botany, a genus of Chrysanthemeie. PYRHELIOMETER, an instrument invented by Pouillet for measuring the amount of heat radiated from the sun. PYRIDINE, CH-.N, a liquid, colorless when pure, possessing a characteristic and unpleasant odor. Boiling point, 115° C. Obtained in the distillation of coal tar. Being strongly basic, pyridine combines with the sulphuric acid used in the process of purifying coal tar prod- ucts. On addition of soda to the acid solution, pyridine is liberated, and is isolated by fractional distillation. Pyri- dine is used as a denaturant for alcohol, and as a solvent in rubber, paint and other industries. PYRITES, an isometric mineral oc- curring frequently crystallized, also massive, in mammillary forms with iibrous structure, and stalactitic with crystalline surface. Occurs abundantly distributed in rocks of all ages, either as crystals, crystal-grains, or nodules, also in metalliferous veins.