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Vincenzo Viviani

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5 April 1622

Florence, Italy

22 Sept 1703

Florence, Italy

Vincenzo Viviani studied at a Jesuit school. His intelligence was quickly seen and a scholarship was provided by the Grand Duke Ferdinando de'Medici to purchase mathematical books for Viviani.

Viviani became a pupil of Torricelli and a disciple of Galileo and worked on physics and geometry. He became a companion and pupil of Galileo from 1639 until Galileo died in 1642. When Torricelli died in 1647 Viviani was appointed to fill the lectureship at the Accademia del Disegno in Florence. The Grand Duke also appointed Viviani engineer with the Uffiziali dei Fiumi, a position he held for the rest of his life.

In 1660, together with Borelli, Viviani measured the velocity of sound by timing the difference between the flash and the sound of a cannon. They obtained the value of 350 metres per second, which is considerably better than the previous value of 478 metres per second obtained by Gassendi (the currently accepted value is 331.29 metres per second at 0 C).

His reputation as a mathematician was high throughout Europe. Louis XIV of France offered him a position at the Académie Royale in 1666, John II Casimir of Poland offered Viviani a post as his astronomer, also in 1666. The Grand Duke, not wishing to lose Viviani, appointed him as his mathematician. Viviani accepted this post and turned down the offers from Louis XIV and John II.

Viviani determined the tangent to the cycloid but he was not the first to succeed in this.

As he was an engineer all his life Viviani published on engineering. In particular he published Discorso intorno al difendersi da' riempimenti e dalle corrosione de' fiumi (1687).

In 1692 Viviani proposed the following problem which aroused much interest. A hemisphere has 4 equal windows of such a size that the remaining surface can be exactly squared - how is this possible?

On his death Viviani left an almost completed work on the resistance of solids which was completed and published by Grandi .

Source:School of Mathematics and Statistics University of St Andrews, Scotland