2 Iv compiling the merits of stamping with other engines,' I wish it to be thoroughly understood that these remarks apply only to gold and silver oies, and only to the latter iv isolated cases,' as it is well known that the ordinary horizontal cylindrical crushers, are more effective than any other descrip tion of machine hitherto invented in separating the ores of copper and lead from a matrix in which they exist in large grains, ,but for the sepaiatiou of the finer-grained lead and tin from the matrix we are still compelled to resort to stamps. In ceitaiii cases where ores have to be subsequently calcined or roasted, dry grinding may be pi eferred, on account of 'the saving in fuel, and for this purpose the cylinder mill with' fine sieve and raff- wheel, assisted by a horizontal stone mill (similar to a flour mill), to re-grind, the lough from the sieve, is decidedly the best, cheapest, and most effective, but the cost of grindiug is more than tieble that of the stamps, and is only compensated by the subsequent saving in labour and fuel. It may be argijed that the waste water from a wet staves cairies off some of the free gold with it, but I have no hesitation m asserting that if it is propeily managed the quantity of gold so lost is so trifling that it would not repay the cost of recovery ; and that eveu in case it could do so, it might be recovered by -causing the waste water to pass through a cunningly contrived amalgamator. 3. I shall now proceed to state the duty which a stamps ,of a given power is capable of doing, and the estimate, of the cost,, exclusive of .primary cost for water power, iuterest of money, &c, and only con sidering 'fho working cost, including lepairs and lenewal 6f machinery, stamp-heads, labour, &c, and sty all premise that'the data aiejtaken from the work ing of the best" pf ' the stamps at Morro Velhb (Sr. 