Ponthus & Therrode, successors to Ponthus & Lepetit, began in
business in Paris around 1895, making sextants, theodolites, and other
instruments of precision. They took over Hurlimann's shop a few years later, and showed their wares at the international exhibition held in Paris in 1900.
Ref: Syndicat des Constructeurs en Instruments d’Optique & de Précision,
L’Industrie Française des Instruments de Précision (Paris, 1901-1902), pp. 211-212.