Hi Cheryl.
Just offering a possibility, not sure.
Emile Prost, 12 rue d"Enghien, Paris.


I think the Emile Prost mark dates to before 1913.
Ernest Prost entered his E. Prost over a fork mark in 1913.
Ernest was also located at 12 rue d"Enghien, Paris, so I'm assuming he suceeded Emile.
Pat.