VIVIANI (Vincentio)
, a celebrated Italian mathematician, was born at Florence in 1621, some say 1622. He was a disciple of the illustrious Galileo, and lived with him from the 17th to the 20th year of his age. After the death of his great master, he passed two or three years more in prosecuting geometrical studies without interruption, and in this time it was that he formed the design of his Restoration of Aristeus. This ancient geometrician, who was contemporary with Euclid, had composed five books of problems De Locis Solidis, the bare propositions of which were collected by Pappus, but the books are entirely lost; which Viviani undertook to restore by the force of his genius.
He broke this work off before it was finished, in order to apply himself to another of the same kind, and | that was, to restore the 5th book of Apollonius's Conic Sections. While he was engaged in this, the famous Borelli found, in the library of the Grand Duke of Tuscany, an Arabic manuscript, with a Latin inscription, which imported, that it contained the eight books of Apollonius's Conic Sections: of which the 8th however was not found to be there. He carried this manuscript to Rome, in order to translate it, with the assistance of a professor of the Oriental languages. Viviani, very unwilling to lose the fruits of his labours, procured a certificate that he did not understand the Arabic language, and knew nothing of that manuscript: he was so jealous on this head, that he would not even suffer Borelli to send him an account of any thing relating to it. At length he finished his book, and published it, 1659, in folio, with this title, De Maximis & Minimis Geometrica Divinatio in quintum Conicorum Apollonii Pergæi. It was found that he had more than divined; as he seemed superior to Apollonius himself.
After this he was obliged to interrupt his studies for the service of his prince, in an affair of great importance, which was, to prevent the inundations of the Tiber, in which Cassini and he were employed for some time, though nothing was entirely executed.
In 1664 he had the honour of a pension from Louis the 14th, a prince to whom he was not subject, nor could be useful. In consequence he resolved to finish his Divination upon Aristeus, with a view to dedicate it to that prince; but he was interrupted in this task again by public works, and some negotiations which his master entrusted to him.—In 1666 he was honoured by the Grand Duke with the title of his first mathematician.—He resolved three problems, which had been proposed to all the mathematicians of Europe, and dedicated the work to the memory of Mr. Chapelain, under the title of Enodatio Problematum &c.—He proposed the problem of the quadrable arc, of which Leibnitz and l'Hospital gave solutions by the Calculus Differentialis.—In 1669, he was chosen to fill, in the Royal Academy of Sciences, a place among the eight foreign associates. This new favour reanimated his zeal; and he published three books of his Divination upon Aristeus, at Florence in 1701, which he dedicated to the King of France. It is a thin folio, intitled, De Locis Solidis secunda Divinatio Geometrica, &c. This was a second edition enlarged; the first having been printed at Florence in 1673.—Viviani laid out the fortune, which he had raised by the bounties of his prince, in building a magnificent house at Florence; in which he placed a bust of Galileo, with several inscriptions in honour of that great man; and died in 1703, at 81 years of age.
Viviani had, says Fontenelle, that innocence and simplicity of manners which persons commonly preserve, who have less commerce with men than with books; without that roughness and a certain savage fierceness which those often acquire who have only to deal with books, not with men. He was affable, modest, a fast and faithful friend, and, what includes many virtues in one, he was grateful in the highest degree for favours.
