OP GUN-METAL.

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of discharges; as formerly in the hottest lieges the firing ha-ving been kept up for some time in the morning was discon-tinued on both sides for three or four hours; this questionremained undecided: but since the powder has been madestronger, and tire siring has continued incessantly from morn-ing till night, so many accidents have happened owing to thesoftness of the metal, that there has been an absolute necessityfor increasing the quantity of tin.

5. On surveying, aster the peace of 1713, the artillery inthe several fortresses in Piedmont ; it was found that thevicissitudes of the preceding war had introduced guns of allnatures; cast by founders of different nations. In the warsof 1733 and 1742, some of these pieces continued perfectlygood after 1000 rounds; while others became unserviceableaster 500, or even fewer discharges: as the shot in strikingagainst the sides had considerably altered the figure of the bore.Many experiments have been made in this capital since thepeace of 1749, both by the officers of the royal corps ofartillery, and by individuals appointed for the investigation ofparticular points, to ascertain the cause of this great diversityof effects. This treatise being only an application of theprinciples of natural philosophy to artillery, it will be best topursue the method adopted in the preceding works, and referto the maxims already established ; that the artillerist maytake in at one point of view their rise, connection and deduc-tion, and be thereby enabled with the greater readiness toapply them to practice.

6. Before we attempt to ascertain the best construction forfire-arms, it will be proper to consider in what their perfectionconsists; that from a clear discrimination of the necessity andimportance of each particular point, we may avoid the errorinto which many have fallen, of paying attention to some cir-cumstances while they neglected others equally essential; thuslosing the advantages resulting from a combination of the severalparts of the subject : hence their labours have only tended use-leflly to multiply the species of ordnance, which has beenalready observed by some excellent writers ; who from thebadness of the inventions have inferred the want of talentsin the inventors.

7. There are two principal conditions which constitute theperfection of every fire-arm : the first requires that it be so(onjirufted that the men who work it may run no ri/k os being

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