tract 35.

EPROUVETTE.

161

accurate and regular. Though the experiments that havebeen tried with this eprouvette, have mostlv been madewith 2 ounces of powder, as a convenient medium charge ;yet it is equally accurate with either more or less than thatquantity ; and it is remarkable that it shows the slightest va-riation that has been made, either in the strength or the quan-tity of the powder.

The instrument is so expeditious, simple, and easy inpractice, that any common soldier, or other person, canlearn the use of it completely in five minutes, employing itwith safety and expedition, and setting down a register ofhis trials. So that, we have thus united in the same machine,the valuable qualities of accuracy, uniformity, ease, and ex-pedition.

The machine can easily be made too by any artist, fromthe preceding description of its construction. Or it can beexecuted at home, and sent to distant places, namely, thesmall parts of it, and there fixed to any small mortar or swi-vel gun.

In the use of this instrument, for the constant regularpractice of proving gunpow r der, a certain mark or number,of the divisions on the arch line, may be fixed on, as astandard for the strength of the powder: which mark, ornumber of divisions, may be ascertained by charging it withany powder of approved strength or quality. And whenonce that mark or number is known, the machine will uni-formly rise to the same place, at every trial, either accurate-ly, or within a small fraction, with the same quantity andstrength of powder. But should any other quality of pow-der be used, the machine will show the difference in itsstrength, with the utmost nicety, whether above or belowthe proof.

12. To practise with this eprouvette; charge it with twoounces, or any greater or less quantity of powder, put inloose, without using any bag or cartridge, and without anyball, in the following manner. Pour the powder carefullyinto the ladle; then, as the piece hangs at rest in the hori*

VOL. III. M