214 
Mr. Weaver on the 
of that estate, and also part of Tigrony, upon their losing the lease 
of the celebrated Parys mine, in Anglesea, of which they were 
the original discoverers. In 1798, they were incorporated by act 
of Parliament, under the firm of The Associated Irish Mine Com- 
pany; and as resident acting partner, I have for many years had 
the immediate direction of the operations. An opportunity was 
thence afforded me of obtaining a full insight into the mineral 
structure of this district, which I shall now describe. 
Metallic substances are diffused through the whole territory, in dis- 
seminated particles, in slight layers, in contemporaneous veins and 
strings, and in massy beds, which last are principally composed of cop- 
per pyrites and iron pyrites. The rocks have been perforated in various 
directions by the subterranean works, the line of which, extend- 
ing into Connery and Tigrony, occupies more than one thousand 
fathoms. The annexed plan and sections of these w^orks will con- 
vey a general idea of their nature, (see Plate 12.); but being laid 
down on a very small scale, the underground excavations are mostly 
omitted in the plan, as they could not be introduced without pro- 
ducing confusion. 
§ 110. The clay slate and quartzose clay slate (§. 62,) contain 
subordinate beds of what are technically termed soft ground ' As far 
as explored, they vary from three to fourteen fathoms in width, 
and extend to an uncertain distance ; but some have been traced for 
more than one hundred fathoms, while in depth they generally 
become more compact and firm. This soft ground, which requires 
timber for its support in the operations of miners, consists of tender 
decomposing clay slate, varying from a light yellow or grey to a 
deep black colour, abounding in pyritous particles, particularly of 
iron, but sometimes also of copper, and even of arsenic ; and gene- 
rally accompanied by a considerable body of greyish or yellowish 
