100

OF GUN-METAL.

portioned according to the different uses for which thebronze was designed : for casting statues, machines, &c.which required nice workmanship, the tin was generallybetween a 20 th and 50 th of the copper, and to give this softmetal a fine colour, they added a proportion of brass, be-tween a s and 5 th of the whole. For bell-metal, whichshould be very hard and entirely free from the separations ofthe particles of metal found in bronze containing too little tin,no brass was used, and the tin was in the ratio of 22 to 27in the 100 of copper.

3. Peter Sardi, an Italian , who fully knew the pro-perties of simple and compound metals, published in the be-ginning of last century, some observations on the damagethat cannon sustain from the explosion of powder: whereinhe pointed out the necessity of having a metal that Jhould beuniformly hard , firm and resisting , not brittle like glass , softlike copper , nor liable to corrode like brass ; but which Jhouldbe able to stand repeated firings without sustaining the leastinjury. These ideas from their justness and accuracy soonspread from Italy, in that day the school of military science,throughout all Europe ; and the Pyrotechncia of VannuccioBiringuccio had already passed through several editions: itwas natural therefore to suppose that the quality of bronzemost proper for artillery would have been universally adopted,and a certain proportion of the component metals fixed on.On the contrary, the most enlightened and warlike nationsproceeded without any determined principles, and variouscompositions were in use till the middle of this century ; asmay be gathered from the numerous publications on thesubject.

4. This variety of opinions gave rife to two parties : theItalians , desirous of having a gun-metal hard and free fromcavities, mixed the tin and copper in the ratio of 12 to 20 inthe 100 ; and by applying a bouch, repaired the guns whenthe vents had run. The opposite party , considering tenacityas the most essential quality, mixed the tin with the copperin the proportion of 4 to 8 in the 100 ; and maintained thatthis composition was the best, as the vents were not so soonaffected by the fire; and attributed the alteration in the boresof the guns, whence they were soon rendered unserviceable,to any other than the true cause, which was the softness ofthe metal. So long as powder was made of a weak quality,and the guns were not over-heated by too quick a succession

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