a town of the grand duchy of Tuscany, capital of the province of the same name, in a fertile plain on both sides of the Arno, 8 miles above its mouth, and 45 W. of Florence. It is surrounded by walls and ditches, about 6 miles in circuit, and is entered by six gates. A great part of the area thus inclosed is occupied by gardens, or entirely unoccupied; and this gives the outer part of the town a very dreary and decayed appearance. But the central part has no lack of cheerfulness and animation; its broad though irregular streets are lined with many stately palaces and gorgeous marble buildings. Both sides of the Arno are lined with quays, and with a street called the Lung d'Arno containing many splendid edifices. Three bridges span the river; one of them, of marble, is among the finest structures of the kind in Europe. In a large open grassgrown space, at the N.W. corner, stand the four most remarkable edifices,—the cathedral, baptistery, leaning tower, and Campo Santo, or cemetery,—all built of white marble in the same style, beautifully grouped together, apart from the other buildings. The cathedral, whose architect was Buschetto, is a splendid building, founded 1067, and consecrated 1118. It is in the form of a cross, with a nave, 4 aisles, transepts, and choir. Its whole length is 311 feet; breadth of the nave and aisles, 106 feet; length of the transepts, 237 feet; breadth of the western front, 116 feet; height from the pavement to the summit of the roof, 112 feet. In the centre rises an elliptical dome, adorned on the outside with eighty-eight columns, and supported in the interior by four piers. The nave is separated from the aisles by twelve Corinthian columns on each side; and these are surmounted by arches; and these again by a number of smaller shafts. The cornices, as well as the bases and capitals of the columns, have been formed by Buschetto with great skill from various fragments of antiquity brought from different places. The twelve altars in the nave and transepts are said to have been designed by Michael Angelo. They are simple in general design, and have much variety in their details. The high altar is heavy; richly and elaborately ornamented. The church also contains many paintings and painted windows, a fine pulpit, and three magnificent bronze doors. It has suffered much from the sinking of the ground, and was greatly injured by a fire in 1596. In the nave is hung a large bronze lamp, the oscillations of which are said to have suggested to Galileo the theory of the pendulum. Opposite the west front of the cathedral stands the baptistery, a circular building 116 feet in diameter, surmounted by a conical dome 102 feet high. In the interior there is a corridor, raised on three steps, running round the building, for the accommodation of spectators of the rite of baptism, which is administered at a large font in the centre. It is of white marble, carved, and inlaid with coloured stones; and has in the centre an image of St John on a column. The baptistery contains a remarkably beautiful pulpit by Niccola Pisano. The exterior of the building is adorned with sculptures and statues. The famous leaning tower of Pisa stands at the other end of the cathedral, overhanging its base more than 13 feet. In shape it is cylindrical, 53 feet in diameter at the base, and 179 feet high; and it consists of eight tiers of columns supporting semicircular arches, and forming as many galleries round the tower. Its leaning position is probably accidental, owing to the sinking of the soil; but it is quite safe, as the centre of gravity falls considerably within the base, and the walls are strengthened with iron bars. The view from the top is extensive and beautiful. The Campo Santo, which stands to the north of the other edifices, is of an oblong form; 415 feet long by 138 broad, and is surrounded by an arcade 34 feet broad and 46 high. In the centre is a mound of earth, said to have been brought from Mount Calvary, and formerly used as a burial-place for its supposed miraculous qualities. The surrounding arcade contains numerous ancient and modern sculptures, and the walls are covered with frescos, some of which are much admired. Pisa contains numerous other churches, some of them remarkable for the beauty of their architecture, or of the pictures they contain: in that of St Catherine is still preserved the pulpit from which Thomas Aquinas used to preach. There are also numerous fine palaces in Pisa. The university of Pisa, founded in the fourteenth century, was formerly one of the most celebrated in Italy; but its faculties of law and philosophy have recently been transferred to Siena. It has nearly 300 students. In the quadrangle stands a fine marble statue of Galileo, erected in 1839. Attached to the university are a library, a museum of natural history, and a botanic garden. The town contains an academy of fine arts, several schools, hospitals, a theatre, &c. It is defended by a citadel to the north, and a fortress to the south of the Arno. Some remains of antiquity, especially of baths, still exist at Pisa. The manufactures of the town are few and unimportant, consisting of cotton and woollen stuffs, soap, white lead, vitriol, &c. The trade has very much declined since the rise of Leghorn. Of the origin of the ancient *Pisa*, which occupied the same site as the modern town, several traditions are given, but little is known with certainty: whether founded by Pelasgians; or, as the poets would have us to believe, by Greeks from the Elean *Pisa*; or, according to a third account, by Etruscans. It was at one time Etruscan; but its early fightings with the Ligurians, and its exploits in piracy and trade, are buried in the dim obscurity of those early times. We do not even know how, nor exactly when, *Pisa* became subject to the growing power of Rome. It certainly was a dependent ally of the republic before the second Punic war, and its port was used as a place of departure for Spain and Gaul. It was also for a long time the frontier city against the Ligurians; and suffered frequently from the invasions of these people in their protracted wars with Rome. In 180 B.C. a colony was established here, and it soon be- came one of the most flourishing places in Etruria; but its history again becomes obscure in the decline of the Roman empire. It passed successively under the dominion of the Goths, Lombards, and Franks, when they conquered Italy; and subsequently became virtually an independent state, owning allegiance nominally to the marquises of Tuscany, who were vassals of the emperor. In this condition the city gradually rose to much importance, and maintained a fleet of galleys, which was employed with much success against the Mohammedan pirates on the coasts of the Mediterranean. They even went so far as to conquer, in 1022, the island of Sardinia, with the assistance of the Genoese, and afterwards that of Corsica, which they received in 1091 as a fief from the Papal See. This was the period of their greatest prosperity, while the city was decorated by its magnificent ecclesiastical edifices. For about four centuries Pisa was one of the most powerful maritime powers in the Mediterranean; but this high rank was lost in the course of the long wars with Genoa, which began in 1070, and resulted in the destruction of the harbour of Pisa in 1290. Meanwhile the city was also engaged in the wars between the Guelphs and Ghibelines in Italy. Pisa supported the latter or imperial party, and was attacked by Florence, the head of the opposite side. It was in these contentions that Ugolino, Count Gherardesca, whose story has been rendered famous by Dante, after being for ten years captain-general of Pisa, was displaced by the Pisans for favouring the Guelph party, and died by starvation, with his sons and grandsons, in the Tower of Famine, which is still pointed out in the city. Peace was at last made with Florence in 1293, and with Genoa in 1299; and the city, now shorn of its naval power, afterwards lost by the same unhappy feuds its independence too. War soon after broke out anew, and Pisa had to contend single-handed against the whole power of Tuscany. In 1326 they lost Sardinia, after repeated attempts to retain it. But the city itself long held out against its foes, and was only reduced by domestic feuds and treachery under the power of Florence in 1406; the chief families proudly withdrawing to Sardinia and Sicily. On the French invasion in 1494, Pisa made a last effort for independence, but was a second time conquered by Florence in 1509. Its liberty was now lost for ever; and it has continued since that time subject to Florence, whose fortunes it has shared. Pisa is celebrated as the birthplace of the famous Galileo. Pop. 25,000. The province of Pisa has an area of 1176 square miles. Pop. (1857) 229,730.

LEONARDO. See ALGEBRA.