1710s, after the Scottish mathematician John Keill effectively accused Leibniz of plagiarism. Contributions to watchmaking In the 1690s, Fatio discovered a method for piercing a small and well-rounded hole in a ruby, using a diamond drill. Such pierced rubies can serve as jewel bearings in mechanical watches, reducing the friction and corrosion of the watch's internal mechanism, and thereby improving both accuracy and working life. Fatio sought unsuccessfully to interest Parisian watchmakers in his invention. Back in London, Fatio partnered with the Huguenot brothers Peter and Jacob Debaufre (or "de Beaufré"), who kept a successful watchmaking shop in Church Street, Soho. In 1704, Fatio and the Debaufres obtained a fourteen-year patent (no. 371) for the sole use in England of Fatio's invention relating to rubies. They later attempted unsuccessfully to have the patent extended to "the sole applying [of] precious and more common stones in Clocks and Watches". In March 1705, Fatio exhibited specimens of watches thus jewelled to the Royal Society. The correspondence of Isaac Newton shows that in 1717 Fatio agreed to make a watch for Richard Bentley in exchange for a payment of £15, and that in 1724 he sought permission from Newton to use Newton's name in advertising his jewelled watches. Fatio's method for piercing rubies remained a speciality of English watchmaking until it was adopted in the Continent in 1768 by Ferdinand Berthoud. Jewel bearings are still used today in luxury mechanical watches. Later life and death Fatio was in Switzerland in 1699, 1700, and 1701. In Duillier he was reconciled to his father and collaborated with his brother Jean-Christophe in surveying the mountains around Lac Léman. He also undertook a deep study of the prophetic books in the Bible. Back in London, Fatio worked as a mathematical tutor in Spitalfields. In 1706 he began to associate with the Camisards, a radical group of Huguenot exiles who had fled from France during the Wars of Religion in that country. The group with which Fatio became affiliated was known as the "French prophets" and preached impending destruction and judgment. The British government suspected the millenarian French prophets of contriving a political scheme, and in 1707 Élie Marion, Jean Daudé, and Fatio were tried before the Queen's Bench on charges brought against them by the mainstream Huguenot churches in London. The three were convicted of sedition and sentenced to the pillory. On 2 December, Fatio stood on