Pierre-Louis Berthoud, 1754-1813. Apprenticed at the age of twelve to his father's workshop and it was not long before his talents were appreciated by his uncle, the celebrated Ferdinand Berthoud, 1727-1807, who brought him to Paris to study.
In 1784, after the suicide of his brother Henry who had run the Berthoud establishment in Paris when Ferdinand retired to pursue his researches, Louis took over the running of the business.
In 1785 Berthoud produced a series of lever watches, but he very quickly abandoned this idea in favour of the detent. He chose the pivoted detent escapement for the longitude watch he supplied to M. Chastenet de Puységur in 1787. Essentially this chronometer set the pattern for all Berthoud's later chronometers, as with the present example. After nine months testing it was presented to the Royal Academy of Science on 10 My 1790. His reward in 1792 was the highest amount available through the system of national awards, 6000 livres, together with an honourable mention.
In a decree of the Consuls of 1802 Louis Berthoud was appointed Clockmaker Mechanical Expert to the Navy and in 1805 the Board of Longitude gave him the title Clockmaker to the Observatory and of the Bureau of Longitude.