The first prototype mechanical tuning fork clock, the 'pendule ç diapason', was manufactured by Louis F. Breguet, grandson of the famous Abraham-Louis Breguet. Louis Breguet filed the patent for this clock in France on October 26, 1866, and a supplement on March 13, 1867. An Irish watchmaker sold this watch in 1961 to the Firm Breguet in Paris, who sold it again a few years later to an unknown collector. Louis Breguet also introduced a clock with a vibrating blade and even mentioned a clock with two tuning forks and another one with two vibrating blades.