360 Sketch of thé Hiftory of | 
more difficult tafk than coming at the metal in the way of 
ftream-works ; it requires more energy of mind, and a moré- 
advanced ftate of the arts. The difficulty that mutt attend 
keeping a mine, funk to forte depth, free from water by 
manual labour only, could not but prevent men, before the 
application of machinery, from diving deep into the bowels 
of the earth. We have, however, fome inftances where old 
workings are found at fo great a depth as to be even now 
with difficulty kept dry by means of machinery; but thefe, 
though they may be counted ancient, were probably opened 
long fubfequent to the origin of mining in this county, 
There are many mines which could not poflibly be worked 
without the aid of gunpowder, and, until the difcovery of 
this powerful agent, underground operations muft have been 
uncertain and difficult. The hammer and wedges of metal 
were probably the firft inftruments for fplitting rocks (and 
they ftill continue, in the ground that will yield to them, to 
be much ufed in Cornwall), and the pick, or inftrument for 
cleaving the ground, having a head for driving the wedges 
called by the miners gads, from a Cornifh word gedn, a 
wedge. The form of thefe inftruments found in old works, 
I think, offers an evidence of their antiquity. A pick, which 
was found in Wheal* Unity tin mine, in Devon, in a part 
not worked certainly for more than eighty years, and which 
could not probably be reckoned to be Jefs than 100 yeats 
.old, does not differ matérially from the form of that now 
ufed; while one difcovered in old workings in Drake Walls 
mine, in the parifh of Calftock in Cornwall, about ten miles 
diftant from the other mine, is of fo différent a fhape as to 
make one conclude, judging by the flow progreffion of 
changes effe€ted on comimon inftruments, that it is of much 
higher antiquity. Wedges of dry wood were alfo very inge- 
nioufly made ufe of, by driving them inio the clefts, and then 
wetting them, fo as to caufe them to fwell and force the 
ground afunder. Tire was an agent long ago employed for 
fplitting the rocks; but the effects of eunpowder fo far exceed 
any thing before made ufe of for fuch purpofes, that its-dif- 
_* In this part of the country the word wheal, fiynifying in the Cornith 
Janguage a work, is generally prefixed to the proper names of mines. 
€ covery 
