[36]. ‘Life of Sterling,’ p. 278.
[37]. London: Longmans, 1857.
[38]. ‘Cornwall, its Mines and Miners.’
[39]. Mr. Samuel Plimsoll (‘Letters on the Iron Trade,’ Times, February 10, 1868) informs us that in the Belgian coal mines the ventilation is carried on in a more economical and effective manner. Here no furnaces are lighted at the bottom of the upcast, because one-twentieth of the coal required for a furnace will make steam for an engine to work fans which act somewhat in the manner of huge paddle-wheels in steam-ships, and by rapid rotation over the shaft produce a draught which the incoming air rushes to meet, and thus powerfully promote ventilation. These fans they can work and control, and are therefore independent of those atmospheric influences to which some of our greatest calamities have been ascribed—the damp, heavy atmosphere of early winter. In the great colliery of Sacrée Madame, near Charleroi, one of these fans will draw 34,000 cubic metres (about 918,000 cubic feet) per minute.
[40]. Recent improvements have done much to render the Davy lamp a more perfect instrument of safety. These more or less insure increased illumination, prevention of bad usage by locking, and more perfect combustion. By an ingenious contrivance, one of these improved lamps cannot be opened without previous extinguishment.
[41]. Experience has proved that when sulphuret of iron undergoes a chemical change into vitriol it disengages a sufficient quantity of heat to set fire to the coal with which it is often found mixed.
[42]. These names were borrowed from the Greek Drachma and the Latin Denarius.
[43]. ‘The Polar World,’ p. 231.
[44]. A very primitive contrivance for raising the water in skin bags.
[45]. Illustrated London News, No. 1477, Saturday, April 11, 1868.