TRACT 35.

EPROUVETTE.

155

been published more than 40 years before ; but I soon per-ceived also, that Baume’s machine was very ill adapted, bothfor convenience, and for accuracy of results.

4. In consequence of such communications, after variousprojects and essays, I at length succeeded to my utmostwishes, in accomplishing the project of a permanent eprou-vette, by means of which, gunpowder may be proved, notonly in an easy, commodious, and expeditious manner, butalso wdth accuracy and uniformity of results; as has beenverified on many occasions, by very numerous trials, and bythe general approbation of all the most competent and dis-interested judges, who have been witnesses of the experi-ments made with it. This machine may be described asconsisting of either a small brass mortar, or gun, suspendedby a metallic stem or rod, turning by an axis on a firm andstrong frame, by means of which the piece oscillates in acircular arch. A little below the axis, the stem divides intotwo branches, reaching down to the gun or mortar, to whichthe lower ends of the branches are firmly fixed, the one nearthe muzzle, and the other near the breech of the piece.The upper end of the stem is firmly attached to the axis,which turns very freely by its extremities, in the sockets ofthe supporting frame ; by which means the gun and stem vi-brate together in a vertical plane, with a very small degreeof friction. The piece is charged wdth a small, but properquantity, of the powder to be proved, without anv ball, andthen fired ; by the force of which the piece is made to re-coil or vibrate, describing an arch or angle, which will begreater or less, according to the quantity or strength of thepowder.

5. To measure the quantity of this recoil or vibration,and consequently the strength of the powder, a circular bra-zen or rather silvered arch, of a convenient extent, and of aradius equal to its distance below the axis, is fixed againstthe descending two branches of the stem, and graduated intodivisions, according to the purpose required to be answeredby the machine, viz, into equal parts, if we would know only