Eprouvette

As used by Ordnance departments and Armories, an Eprouvette is a one piece, fixed elevation mortar used to test the strength of gunpowder. It went out of general use by the middle of the 19th century. In use, a carefully weighed quantity of powder (charge) was placed inside, 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. It was first introduced in the middle of the 1600s.