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 VOLTAIRE

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VOLTERRA

to have a small posit ivo, and I he copper an equal negative charge, a result, which has been confirmed by subsequent investigators working with more deli- cate instruments, notably by Lord Kelvin. Anterior to this, in 1775, Volta devised his olectrophorus by means of which, given a small initial electrification, mechanical work may be transformed at will into energy of electrostatic charge. Though the princi- ple involved was known to Canton of London in n.'i.S, and though VVilcke of Sweden de- scribed an elec- trophorus in 1762, Volta's was the first practical machine of the kind and, therefore, the pro- toty[5eof therotary influence maeliines of the present day, such as the Holtz, the Voss, and the VVimshurst. In 1777 he proposed a system of electric telegraphy in which signals were to be transmitted by means of his electrophorus over a line extending from Como to Milan. The first use of static electricity for telegraphic purposes was, however, suggested in the "Scots Maga- zine" for 17.5.3 and carried out on a small scale in 1774 by Lesage of Geneva.

In seeking further experimental evidence in favour of his contact theory, Volta was led to the greatest of his inventions, the voltaic "pile", which he described in a communication of 20 March, 1800, to Sir Joseph Banks, President of the Royal Society of I^ondon. Consisting as it did of a number of discs of zinc and copper separated by pieces of wet cloth and arranged in a vertical column, it was appropriately called a "pile"; a more efficient arrangement was, however, soon found by Volta in the "crown of cups". The voltaic battery of 1800 marks an epoch in physical theory as well as in the application of science to the welfare of mankind. Though Volta hved twenty- seven years after the crowning invention of his fife, it is a significant fact that he added nothing of note to his great work, leaving to Carlisle and Nicholson in 1800 to use the current furnished by a "pile" to decompose water; to Sir Humphry Davy in 1807 to separate sodium and potassium from their alkalis by the same means; and to Oersted of Copenhagen the cardinal discovery in 1820 of the magnetic eiTect of the electrical current.

Honours were showered on Volta by the academies and learned societies of Europe. Napoleon invited him to Paris in 1801 and made him an associate mem- ber of the Institut de France and later a senator of the Kingdom of Italy. In 1815 the Emperor of Aus- tria appointed him director of the philosojjhical faculty of the University of Padua, a dignity which he resigned four years later in order to retire into pri- vate life. In the summer of ISO!), the centenary of the invention of the voltaic hat I cry, an exposition was held in Como of electrical ajiparatus constructed and used by Volta in his investigations, but unfor- tunately a fire broke out and many of these heirlooms of science were destroyed. Three practical units have been named after Catholic electrical ijioneers; the volt, the unit of electrical pressure, in honour of Volta; the coulomb, the unit of electrical quantity, in honour of Charles Augustin de Coulomb; and the

ampere, the unit of current, in honour of Andre-Marie Ampere.

BuNCHi AND MoccHETTi, Vita di Volta (Como, 1829-32); Zanino Volta, Atessandro Volta (Milan, 1875); Idem, Alesmndro Volta a. Pariai (Milan, 1879).

Brother Pot.'vmi.\n.

Voltaire. See France, sub-title, French Lit- erature.

Volterra (Ricciarelli), Daniele da, Italian painter, b. at Volterra, 1509; d. in Rome, 1566. Ricciarelli was called Volterra from the place of his bu-th. As a boy, he entered the studios of Bazzi (II Sodoma) and of Baldassare Peruzzi at Siena, but he was not well received and left for Rome, where he found his earliest employment. He formed a friend- ship with Michelangelo, who assisted him with com- missions, and with ideas and suggestions, especially for his series of paintings in one of the chapels of the Trinity dei Monti. By an excess of praise, his great- est picture, the "Descent from the Cross", was at one time grouped with the "Transfiguration" of Raphael and the "Last Communion" of Domenichino, as the most famous pictures in Rome. His principal work was the " Murder of the Innocents", which he painted for the Church of St. Peter at Volterra, now in the Uffizi Gallery, Florence. Volterra was commissioned by Paul III to complete the decoration of the Sala Regia. On the death of the pope (1549) he lost his position as superintendent of the works of the Vatican, and the pension to which it entitled him. He then devoted himself chiefly to sculpture. Com- missioned by Paul IV to supply draperies to some of the nude figures in the magnificent "Last Judgment" by Michelangelo, he thus obtained the opprobrious nickname "Breeches Maker" or "II Bragghetone". His "Victor)' of David over Gohath", now in the Louvre, is so good that for years it was attributed to Michelangelo. His work is distinguished by beauty of colouring, clearness, excellent composition, vigor- ous truth, and curiously .strange oppositions of light and shade. Where he a p - proaches closely to Michelangelo, he is an artist of great importance; where he partakes of the sweetness of Sodoma, he be- comes full of man- nerisms, and pos- sesses a certain exaggerated pret- tiness. A recent author has wisely said: "He exag- gerates Michaol- angelo's peculiari- ties, treads on the dangerous heiglits of sublimity, and. not possessing his master's calm

lUsT OF Michelangelo

i-lo ila VoltiTr.i. National Mu

Florence

jjower, is apt to slip down. " His position in present- day criticism is very different to what was given to him a generation ago, and more nearly approaches to a truthful view of his art.

Vasari, Vitf dei 'pittori; Bryan, Did. of Painters and Enyraters (London, 1904), a. v. Ricciarelli.

George Charles Williamson.

Volterra, Diocese op (Vol.\terhanensis), in Tuscany. The city stands on a rocky mountain 1770 feet al)ov(> the .sea level, between the rivers Bra and (\'cina, and is surrounded by strong walls. The