J(ules) J(oseph) Grandjon was a Frenchman who worked around Europe before founding a Violin making factory in Mirecourt, France in 1850. I can find nothing to say when the factory stopped producing, and all of the Violins I have seen are dated pre 1900, so I think they were gone by WW1. Though most famous for Violins they did produce some other Instruments too, including an early Ukulele / Cavaquinho / Hawaiian Mandolin type model.