Wiktionary
n. A one-piece, fixed-elevation mortar formerly used to test the strength of gunpowder.
Wikipedia
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.
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.
Usage examples of "eprouvette".
The second appeared, and the eprouvette positive was gloriously renewed.
Feeling strange as well, for his recent experience had led him to fear that the mere existence of the Henry repeating rifle or the eprouvette mortar made all talk of spirit immediately antique.
Haskell called up his eprouvette mortars and put them just beyond the lip of the crater and had them loaded with a scant ounce and a half of powder, since all they had to do was loft the shells fifty feet to where the Federals milled about like a pen of shoats waiting for the hammer between the eyes.