Henri Grandjean was born in Le Locle on December 14, 1803. From 1824 until 1830 he was assigned the task of organizing the South American branches of his father’s company; in 1830 his brother Henri Gustave emigrated to Peru and was from then on in charge of these businesses. Henri Grandjean trained as a watchmaker in his home town. Around 1830 his factory "Henri Grandjean & Cie." began to build ship’s chronometers that were modelled on the English chronometers. His business partner was Edouard Thévenaz; together with Louis Jean Richard and Ulysse Nardin. Grandjean was the originator of the Swiss marine chronometer production. In 1875 Henri Grandjean won the first price at the Neuchâtel Chronometer Contest for a marine chronometer. Henri Grandjean died in 1879. In 1899 Rossel & Fils, Le Locle, registered their name as successors to Henri Grandjean & Cie.
• Jaquet, Eugène, and Chapuis, G.A Berner, S. Guye, Technique and history ot the Swiss watch , Spring Books, Hamlyn Publishing, New York 1970 • Journal Suisse d'horlogerie, V.3, No 5, Nov. 1878 "Exposition Universelle de 1878" page 192