Boulenges chronograph for the determination of the velocity of projectiles, with zinc tubes for records, includes additional zinc tubes and an illustration Boulenges chronograph for the determination of the velocity of projectiles 1867
d'Arsonval electric chronometer, for measuring reflex reaction time, by Charles Verdin, Paris, 1902 d'Arsonval electric chronometer, by Charles Verdin, Paris, France, 1902 1902