74 
WHEREVER there are mines, (subterraneous 
excavations), metals of some sort or other are 
produced; and it surely is not burthensome to 
the intellect to distinguish lead ore from copper, 
or silver from lead, or gold from iron, or dia- 
monds from pebbles. 
PERMIT me to advise the traveller to look 
into the book of nature, which is always open, 
and learn what he can. A little information 
on this head may prove highly advantageous, 
as the wealth of nations mostly depends on 
the produce of their mines. It is earnestly 
to be recommended, wherever he gues, to 
bring from thence some specimens of the 
rocks; and if any other present themselves, he 
should endeavour to possess himself of them, 
which he might examine at leisure, with the 
blow-pipe: the use of this instrument, and the 
mode of managing it, are fully explained in’ a 
