TRACT 35.

EPROUVETTE.

157

and versed sines of the recoil, by which the true propor-tions of the velocities of balls, or the strength of powder, isshown.

3rd. The manner of applying the index, making it bearwith a gentle pressure against the side of the socket of thestem, by means of a spring, and fixing it by a stop, whilethe gun and arch make the first or greatest vibration back-wards.

7. In the course of the year 1783, I procured to be exe-cuted in London, by skilful artists, under my direction, twopf these eprouvettes. The first was a small model in brass,with a small gun of about 6 inches in length; which, not-withstanding the diminutive size, performed very satisfacto-rily, being charged with proportionally small quantities ofpowder. The other was a machine executed in wood, and ofthe full intended size, the gun nearly 2£- feet in length ; beingintended to serve as a pattern, by which to construct thelarge machine in metal. Both these machines were placedin the grand Artillery Repository, under the care of MajorCongreve, in Woolwich Warren, now called the Royal Ar-senal. From this wooden pattern, the complete machinewas soon afterwards constructed iti metal, in Major Con-greve’s office, at my request, by order of the Duke of Rich-mond, then Master General of the Ordnance; who was alsopleased to give orders that it should undergo proper trials,and the results to be reported to him ; which was done ac-cordingly, with very general satisfaction and approbation,by the board of field-officers. This machine, after manyuseful experiments had been made with it, was also placedin the Repository, beside the former models, to be in readi-ness for use on any occasion that might occur ; but wherethey were mostly destroyed, togetlvir with most of the othercontents, when that noble institution was unfortunately con-sumed by fire in the year 1802. I trust however that a newone may have been since constructed, and placed in the NewRepository in the Barrack Field, as a substitute for the for-mer, for the good of the service.