METHOD OF WORKING THE MINES.
The method of raising the ores, and the processes pursued in separating the metal, are, upon the whole, extremely simple. A pick-axe and shovel are the only tools in use for removing the earth; and the drill, rammer, and priming-rod, are added when it is necessary to blast. Having determined on the spot for digging, the process commences by measuring off a square of about eight feet, and throwing out the earth, spar, and gravel, until the miner sinks beneath the depth he can throw the earth. An expert hand will pitch his earth clear out of the pit from a depth of ten, twelve, and even fifteen feet. At this depth a common windlass and bucket are placed over the centre of the pit, and the digging continued by drawing up the earth, spar, and ores, if any are found, in the manner pursued in sinking a well. During his progress, the miner is notified of his approach to a body of ore, by small detached lumps occasionally found imbedded in the soil, within a few feet of the surface. Sometimes lumps on the top of the ground determine on the place for digging. The spar is also a sign by which he judges, as there is seldom a body of spar found without lead-ore. There are also other signs by which an experienced digger is advertised of his prospects, and encouraged to proceed with cheerfulness in his work. These are, peculiar appearances in the texture of the spar, and sometimes minute specks of ore scattered through it, the changes in the color, and other qualities of the earth, gravel, &c. If these appearances are promising, and bits of ore are occasionally met with, he is encouraged to sink down a great depth; but if they should fail, he is generally induced to abandon the pit, and commence at another place.
In searching for ore, the soil, the slope of the hills, spar, blossom, trees, &c., are taken as guides, and some are obstinately attached to these signs. Others, who have been fortunate in finding ore where these appearances were least promising, wholly disregard them, and pay no attention to rules. In general, there is a greater disposition to trust to luck and chance, and stumble upon ore, than by attending to mineral character, to be sure of success. As those who search by rules are generally incapable of those minute remarks on the distinguishing character and geological situation of minerals, which are necessary in order to ensure success, it frequently happens that they meet with disappointments. An incident of this kind is enough to perplex a man who has not habituated himself to reasoning on the subject, and to weaken his belief in the affinity of ores and stones. Such a man will not stop to compare and reconcile facts, which are seemingly opposite, or to investigate the nature of general principles.
Hence miners exclaim on the uncertainty of finding ores by rules drawn from the observations of science; that the strata of the earth are irregular, and not to be depended upon like the rock formations in Europe; and that, in fine, we have no guides by which its mineral treasures are to be sought, and that, in so confused a soil, chance is the best guide. Such a man is more ready to follow the mysterious guidance of the divining-rod than the light of reason, and would be easily persuaded that fortune is more surely the result of blind chance, than of feasible schemes, well planned and well executed.
There would be, nevertheless, some truth in the uncertainties and the confusion complained of, were those circumstances among the observations of scientific men. But it will be hazarding little to say, that when such observations are made, there will be found as much regularity, harmony, and order, in the superposition of the strata, as generally exist. The few facts I have noticed, lead to this conclusion.
Having raised a sufficient quantity of ore for smelting, the next process consists in separating the spar, and cleaning the ore from all extraneous matter. This is done by small picks, tapered down to such a point that a careful hand may detach the smallest particle of adhering spar. It is necessary that the ore should be well cleaned, as it would otherwise prove refractory in smelting. If there be any lumps of uncommon size, they are beaten smaller. The object is to bring the lumps as near as may be to an uniform size, so that the heat may operate equally in desulphurating the ore. It is desirable that the lumps should be about the size of a man's two fists, or perhaps fifteen pounds' weight; if too small, a difficulty and a waste is experienced in smelting. In this state, the ore is conveyed to the primary furnace, (see Plate I.) and piled on the logs prepared for its reception. When the charge is put in, which may in a common way be about five thousand pounds, it is surrounded by logs of wood, and covered over at the top, the fire being lit up at the mouth below. A gentle warmth is created at first, which is raised very gradually, and kept at this point for about twelve hours, to allow the sulphur to dissipate; the heat is then increased for the purpose of smelting the ore, and, in twelve hours more, the operation is completed, and the lead obtained. Wood is occasionally added as the process goes on, and there is a practical nicety required in keeping the furnace in proper order, regulating the draught of air, &c., so that some smelters are much more expert, and thereby extract a greater quantity of lead from a like body of ore, than others. This furnace is called the log furnace, and, so far as I know, is peculiar to this country. It is of a very simple construction, consisting of an inclined hearth, surrounded by walls on three sides, open at top, and with an arch for the admission of air below. Upon the whole, it appears well adapted to the present situation and circumstances of the people. It is cheap, simple, may be built at almost any place, and answers the purpose very well. A good furnace of this kind may be built at a cost of from fifty to sixty dollars, every expense considered; and one of the most considerable items in the sum total is the bill of the mason, who cannot be hired, in this region, to work for less than two dollars per day.
Plate I., Figure 1. A Perspective View of the Log Furnace.
a, the front wall, 8 feet long, 7 feet in height, and 2 feet in thickness.
b b, the side walls, 8 feet long, and 2 feet thick.
c, the hearth, 2 feet wide, and 8 feet in length.