Invented by Ferdinand Berthoud, the pendulum of this regulator is described in his Essai sur l' Horlogerie, 1763, vol. 2, pl. XXXIV, pp. 302 and 303. It is constructed from three bars only, two of steel, one in brass. In order to perfect the compensation, F. Berthoud devised an auxiliary adjustable compensation lever ("L" on the design), mounted between the bar of brass and one of the steel bars. The pendulum is also fitted with a thermometer. The bob is offset relative to the centre line of the pendulum, apparently to avoid any distortion of the bars. At rest, the gridiron is therefore at an angle from the vertical. This type of pendulum was soon abandoned in favour of the 9 rod gril-iron pendulum. To date, only four regulators, including this lot, fitted with this form of pendulum are known, one of which is preserved in the Musée National des Techniques (C.N.A.M.), Paris. Jean Martin Jean Martin was related to some trusted servants of Berthoud at Groslay to whom he left a bequest in his will. When he retired to his house of Groslay in 1779, to write his books and continue his research, Jean Martin became his last pupil and most faithful collaborator. Most of the marine timepieces by Berthoud made at Groslay were constructed by Jean Martin, such was watch No. 3A, made in 1796, now in the Olivier Collection at the Musée du Louvre. About Jean Martin, Berthoud wrote in the Supplément au Traité des Montres n Longitudes - 1807 - p. 30: 'He \vas born in my house at Groslay in 1773. When he had reached the age of 13, having set him to work for a period under the supervision of one of my workmen, I found him to have dexterity and intelligence. As a result I decided to make a clockmaker of him and sent him to do his apprenticeship with Vincent Martin, the clockmaker to the Navy at Brest with whom Jean Martin worked for five and a hait years. Jean Martin returned to Groslay in 1793. He worked with me for nearly nine years. During this time, under my direction he realised several longitude time-pieces and year going astronomical clocks. Having committed himself to setting up in Paris I obtained work on several watches for him, among others watches for Monge, Guyton-Morveau, Legendre who were content with the zeal and care that he took. I believe I have placed at the disposal of connoisseurs a useful and distinguished artist. Jean Antoine Claude Chaptal 1756-1832 Jean Antoine Claude Chaptal, Comte de Chanteloup was born at Nozaret, (Lozère ) on 4 June 1756 the son of an apothecary. He studied chemistry at Montpellier where he obtained his doctorate in 1777. In 1781 the Estates General of Languedoc founded a chair of chemistry for him and there he taught the ideas of Lavoisier. With the help of an inheritance from a wealthy uncle he established a minerai acid manufacture thus affirming his life-long involvement with industriel chemistry for which he was eventually granted letters of nobility. Active but discretely moderate during the revolutionary period he was made councillor of state by Bonaparte and succeeded Lucien Bonaparte as Minister of the Interior. As such he greatly advanced the sciences and arts in France founding a chemical manufactory near Paris, a school of arts, a society of industries reorganised the hospitals and was responsible for metrification. After Napoleon's fall he was obliged to retire into private life and his name was removed from the list of peers until 1819. In 1816 however he had been nominated to the Académie des Sciences by Louis XVIII and his researches and publications, even more than his public activities had major consequences for the developement of useful science in France. His major works la Chimie appliquée aux arts ( 4 vols, 1806) and De l'industrie française ( 2 vols 1819) were widely rend and used, but his name remains indissolubly linked with vine-making on which he published an important treatise, for the process of 'Chaptalisation', that he introduced.