ON METALS. 287 



frequency of the firing; the mixture of which it was made con- 

 tained a large portion of lead ; and it would have been less prone 

 to melt, and consequently preferable, had it contained none. 



Woolwich, I believe, is the only place in England, where there 

 is a foundry for the casting of brass cannon. The metallic com. 

 position there used, consists of copper and tin. The proportion 

 in which these two metals are combined, is not always the same, 

 because the copper is not always of equal purity, and the finest 

 copper requires the most tin ; they seldom use more than twelve, 

 or less than eight parts of tin to every 100 of copper. This 

 metallic mixture is sold, before casting, for . 75 a ton, and 

 Government pays for casting it .60 a ton. The guns of the 

 East India Company are less ornamented than those of Govern, 

 ment ; on that and other accounts they are cast for . 40 a ton. 

 I have here put down the weights of the brass ordnance, now 

 most generally in use, as cast at Woolwich. 



Weight of brass cannon now in use. 



cwt. qr. Ib. 



4-2 pounders . . 61 2 10 



24 . . . 51 



12 . . . 29 



6 . . . 19 



These were on board the Royal George in 1780, but had been 

 removed, I believe, before she was losf. 



Battering cannon. 



42 pounders . . 61 2 10 



32 . . . 55 2 10 



24 . . . 51 



18 . . . 48 



12 . . . 29 



9 . . . 25 



6 . . . 19 



Field-pieces. 



24 pounders . : 16 3 13 



12 . . 838 



6 . . . 4 S 19 



3 . . 2 3 10 



