An French: eprouvette is a one piece, fixed elevation mortar used by ordnance departments and armories to test the strength of gunpowder.
A carefully weighed quantity of powder (charge) was placed inside the device, followed by a standard weight shot. The charge was fired and the distance the shot flew was measured and compared to the expected standard distance. French: Eprouvettes were first introduced in the middle of the 1600s and went out of general use by the middle of the 19th century.[1]
French: Eprouvettes were also used to test the strength of small-arms powder, starting in the second half of the 1500s. These evolved into pistol-size devices which were used until the end of the black powder era, at the close of the 1800s.[1] [2]