Louis-Clément Breguet Paris Tuning-fork clock Nickel-plated metal, brass, steel Height: 46 cm. Width: 26 cm. Depth: 19 cm. Dial signed: BREGUET N° 1150 BREVETE SGDG Case signed: BREGUET Initials PK at base of diapason. Finished in 1868 The nickel-plated metal case has glass on all four sides. The annular dial is engraved with Roman numerals for the hours and Arabic numerals for the five minutes, with a small eccentric seconds dial in the upper part. The clock movement was built on the principles set down in patent n° 73414 registered on 20 October 1866 by Louis-Clément Breguet. It has two barrels, a train and an escapement. The regulating organ is a steel tuning-fork, two hundred and fifty millimetres in length and vibrating at one hundred hertz. One of its arms touches the escapement, whose function is to keep it vibrating. History: 1967 (purchased). Finished in 1868. Exhibitions: 1867, Paris 1997, MIH, p. 33, illus. Bibliography: Comptes Rendus de l’Académie des Sciences, volume LXIII, 1866, p. 991. George Sire, Rapport sur l’horlogerie à l’Exposition Universelle de 1867, Paris, s.d. Frédéric Marle, "La pendule à diapason de Louis Breguet", Annuaire de la montre suisse, 1964, 1965. MIH, 1974, p. 131, illus. Breguet, 1997, p. 335, illus.