492 
JOURNAL OF THE PLYMOUTH INSTITUTION. 
The proposition to work at greatly increased depths has been 
steadily opposed by most of the old miners ; but those who are 
acquainted with the incessant active opposition or contemptuous 
neglect of the aids offered for facilitating work, experienced in 
most of the Cornish mines, can see no sufficient reason for not 
accomplishing the scheme with the aid of the younger hands, who 
have gone forth and learnt new lessons in the mountains of Cali- 
fornia, Nevada, and Australia, and have come back ready and 
willing to apply their experience for the benefit of their old home. 
Cornish engineers are to be found ready, if allowed, to revive 
the celebrity of the achievements of the Cornish pumping engine, 
and not only so, but to apply to their perfecting, the improvements 
made in the construction of locomotive, marine and other engines. 
By the general introduction of the steel wire rope and improved 
hauling engines, of boring machines, of improved blasting agents, 
of Blake's crusher, of one of the many forms of stamping machines, 
instead of the old Cornish stamp, by the use of good coal, by 
adopting the best known methods of preparing ores for the market, 
there are already sufficiently obvious methods of converting many 
unprofitable mines into dividend-paying companies. There is yet 
another source of improvement that has already been adopted 
with very great advantages by a few mines that requires notice. 
It has been the common practice to work a mine for one metal 
only, and so if a mine had been denominated a copper mine, and 
laid out accordingly, the presence of other metals would most 
commonly be ignored. Already, in looking over the reports of 
some few mines, we may find returns given of the value of ores 
sold, for copper, tin, arsenic, wolfram, tungstate of soda, cobalt, 
nickel, bismuth, &c. ; but what has already been done is but a 
very small earnest of the improvements that yet remain to be 
worked out. In illustration of this, let us take some of the ores 
on the lecture table. The sample before us contains, we will 
suppose, in round numbers : 
Copper 3 
Tin 2 
Arsenic 20 
Sulphur 30 
Iron 30 
Wolfram 5 
Silica and Alumina . . . . . .10 
100 
