Berthoud, Ferdinand (1727-1807) Berthoud was a chronometer-maker born at Plancemont, near Neuchatel, Switzerland, on March 19, 1727. From a very early age he showed interest in mechanical matters. His father therefore decided to have him taught cloclanaking and, at the age of 14, Ferdinand was apprenticed to his brother Jean Henri. When he was 19, he went to Paris, where another brother, Jean- ,Jacques, a designer, was already established. It is thought that he worked for Julien Le Roy for some time. Ferdinand, uncle of Loris Berthoud and rival of Pierre Le Roy, established himself in Paris in the Rue de Harley, Ile de la Cite in 1745. In 1752 he presented to the Academy of Science an equation watch with a perpetual calendar. By order of the King, he went twice to England, with Camus and Lalande, to examine John Harrison's marine clocks but Harrison only let him see numbers 1, 2 and 3, not number 4. However, on his seconcl t rip to England in 1766, Berthoud obtained from Thomas Mudge the information he needed concerning Harrison's number 4, which allowed him to enlarge his own researches. He then undertook the construction of his own marine clocks 6 and 8, which competed for the prize for the best way of measuring time at sea, proposed in 1767 and 1769 by the Academie Royale des Sciences. These timekeepers were tried at sea in 1768 and 1769 by Eveux de Fleurieu, commanding the frigate Isis, and, with those of Pierre Le Roy, in 1771 and 1772 by Verdun de la Crenne. Despite the influential support of Fleurieu, it was finally Pierre Le Roy who received the double prize of the Academic. During the course of his career, Berthoud received various official appointments among which: Horloger de la Marine ( Clockmaker to the Royal Navy); Member of the Institute of France; Fellow of the Royal Society of London; and, Chevalier of the Legion d'Honneur. Berthoud trade many experimental marine watches, most of which, purchased by the Government, are preserved in the Maser Nationale des 'Iirchaiques ( C.N.A,M.), Paris. They include swatches and clocks with equation of time, seconds watches, and superb astronomical longcase clocks fitted with compensated pendulums which he invented. All the timepieces that he made show his great dexterity, and the exceptional quality of his execution. The details of their construction and the experiments he carried out with the instruments are described in the numerous books that he published at government expense. The precision instr uments that he invented enabled Berthoud to perfect a rigorous experimental technique, adopted by all his successors, and particularly by his nephew Pierre Louis Berthoud, who was also his pupil. Other chief pupils of his were Jacques and Vincent Martin. Ferdinand Berthoud, who had married twice, firstly Mademoiselle Chatri of Caen, and then Mademoiselle Dumoustier of Saint Quentin, died on 20 June 1807, in his property at Groslay, near Montmorency, leaving no children.