Note 7 — Chapter XIX · A VISIT TO A GOLD-MINE.

These are the beginning of the so-called gold-mines. The subterranean work, which is carried on principally during the winter months, does not differ much from the ordinary work of the miner. Poisonous vapours do not usually occur, but, when cutting through clay-slate, the presence of sulphate of cobalt has sometimes an injurious effect. The passages are nine feet wide and high, and two labourers generally work from two to three tons of sand per day. The sand thus accumulated during the winter is thrown up into heaps and washed in the summer.