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A man whose great qualities want the ornament of superficial attractions, is like a naked mountain with mines of gold, which will be frequented only till the treasure is exhausted.

Rambler.

Can gold calm passion, or make reason shine? Can we dig peace, or wisdom, from the mine? Wisdom to gold prefer; for 'tis much less, To make our fortune, than our happiness. Young. MINE, in the military art, a subterraneous passage, dug under the wall or rampart of a fortification intended to be blown up by gunpowder. It is commonly about four feet square; at the end of this is the chamber of the mine, which is a cavity of about five feet in width and in length, and about six feet in height, and here the gunpowder is stowed. The saucisse of the mine is the train, for which there is always a little aperture left. Two ounces of powder are capable of raising two cubic feet of earth; consequently 200 oz., or 12 lbs. 8 oz., will raise 200 cubic feet, which is only sixteen feet short of a cubic toise, because 200 oz. together have proportionably a greater force than two ounces, as being a united force. All the turnings a miner uses to carry on his mines, and through which he conducts the saucisse, should be well filled with earth and dung; and the masonry in proportion to the earth to be blown up, as three to two. The entrance of the chamber of the mine ought to be firmly shut with thick planks, in the form of St. Andrew's cross, so that the enclosure be secure, and the void spaces shut up with dung or tempered earth. If a gallery be made below, or on the side of the chamber, it must absolutely be filled up with the strongest masonry, half as

long again as the height of the earth; for this gallery will not only burst, but likewise obstruct the effect of the mine. The powder should always be kept in sacks, which are opened when the mine is charged, and some of the powder strewed about; the greater the quantity of earth to be raised is, the greater is the effect of the mine, supposing it to have the due proportion of powder. The branches which are carried into the solidity of walls do not exceed three feet in depth, and two feet six inches in width nearly; this sort of mine is fit to blow up the strongest walls. The weight of a cubic foot of powder should be 80 lbs.; one foot one inch cube will weigh 100 lbs.; and one foot two inches and eleven-twelfths, 150 lbs. ; and 200 lbs. of powder will be one foot five inches cube; however, there is a diversity in this, according to the quantity of saltpetre in the gunpowder. If, when the mines are made, water be found at the bottom of the chamber, dry planks are laid, on which the powder is placed either in sacks or barrels of 100 lbs. each. The saucisse must have a clear passage to the powder, and be laid in an auget or wooden trough, through all the branches. When the powder is placed in the chamber, the planks are laid to cover it, and others again across these; then one is placed over the top of the chamber, which is shaped for that purpose; between that and those which cover the powder props are placed, which shore to the inside of the wall, all the void spaces it up; some inclining towards the outside, others being filled with earth, dung, bricks, and rough stones. Afterwards planks are placed at the entrance of the chamber, with one across the top, whereon they buttress three strong props, whose other ends are likewise propped against another plank situated on the side of the earth in the branch; which props being well fixed between the planks, with wedges, the branch should then be filled up to its entrance with the forementioned materials. The saucisses which pass through the side branches must be exactly the same length with that in the middle, to which they join; the part which reaches beyond the entrance of the mine is that which conveys the fire to the other three; the saucisses, being of equal length, will spring together.

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The force of a mine is always towards the weakest side; so that the disposition of the chamber of a mine does not at all contribute to determine this effect. The quantity of powder must be greater or less in proportion to the greater or less weight of the bodies to be raised, and to their greater or less cohesion; so that we must allow for each cubic fathom of loose earth 9 lbs. or 10 lbs. Of firm earth and strong sand, 11 lbs. or 12 lbs. ; of flat clayey earth 15 lbs. or 16 lbs. ; of new masonry, not strongly bound, 15 lbs. or 20 lbs.; and of old masonry, well bound, 25 lbs. or 30 lbs. The aperture, or entonnoir of a mine, if rightly charged, is a cone, the diameter of whose base is double the height taken from the centre of the mine. When the mine has been overcharged, its entonnoir is nearly cylindrical, the diameter of the upper extreme not much exceeding that of the chamber. Besides the shock of the powder against the bodies

it takes up, it likewise crushes all the earth that borders upon it, both underneath and sidewise. To charge a mine, so as to have the most advantageous effect, the weight of the matter to be carried must be known; that is, the solidity of a right cone, whose base is double the height of the earth over the centre of the mine; thus, having found the solidity of the cone in cubic fathoms, multiply the number of fathoms by the number of pounds of powder necessary for raising the matter it contains; and, if the cone contains matters of different weights, take a mean weight between them all, always having a regard to their degree of cohesion. As to the disposition of mines, there is but one general rule, viz. that the side towards which one would determine the effect be the weakest; but this varies according to circumstances.

It has been found by experiments that the figure produced by the explosion is a paraboloid, and that the centre of the powder, or charge, occupies the focus. The place where the powder is lodged is called the chamber of the mine, or fourneau. The passage leading to the powder is called the gallery. The line drawn

from the centre of the chamber, perpendicular to the nearest surface of the ground, is called the line of least resistance. The pit, or hole, made by springing the mine, is called the excavation. The fire is communicated to the mine by a pipe, or hose, made of coarse cloth, whose diameter is about one inch and a half, called a saucisson (for the filling of which near half a pound of powder is allowed to every foot), extending from the chamber to the entrance of the gallery, to the end of which is fixed a match, that the miner who sets fire to it may have time to retire before it reaches the chamber.

To prevent the powder from contracting any dampness, the saucisson is laid in a small trough, called an auget, made of boards, three inches and a half broad, joined together lengthwise, with straw in it, and round the saucisson, with a wooden cover nailed upon it.

Foyer, Fr. Focus or centre of the chamber. Some authors call the end of the saucisson that comes within the work, and which is to be set fire to, the foyer, or focus; but by most people, this is generally understood to be the centre of the chamber.

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MINES. To carry on all the processes of the mine requires the combination of very considerable skill in several difficult branches of engineering. Most countries in which metallic veins are found, have the strata under the upper soil, consisting of rock of various degrees of hardness, it is therefore an essential part of the miner's art, and what indeed particularly distinguishes him from a common laborer, to be able to break ground of this sort under all the disadvantages of being cramped for room, exposed to constant streams of water, and not unfrequently to unwholesome air.

In Cornwall the workmen generally divide the ground, or rock, into two general classes, one of which they call working ground, and the other is distinguished by the name of shooting ground. The first class includes all such kinds of rock as may be separated or broken by the use only of the pick and wedge, which latter is technically called a gad.

The latter denomination is applied to all rock that is so hard as to require the use of gunpowder, which is bored by tools of steel, and loosened and detached by the explosion of the charges rammed into the holes.

The tools used by the miners of Cornwall and Devon are simple, and in their hands very effective; the form of the principal ones is delineated in MINING, plate I.

The pick, fig. 2, is usually of the shape shown in the drawing, but it is varied a little for some purposes, or for different kinds of rock; the one side is used as a hammer, and is called the poll, it serves to drive the gads, or to detach and loosen projecting parts; the point is steel, carefully tempered, and drawn under the hammer to its proper form, in which considerable nicety is required, as one kind of point will not do for all

kinds of ground. The weights of picks are likewise various, according to the situation and circumstances in which they are to be used, but are never very heavy, as experience has fully shown that a rapid succession of smart blows, which may be given by a light tool, produces more effect than a less number from a weighty instrument, which soon tires the workman.

The gads, fig. 3, are wedges of steel, which are driven into crevices of the rock, or into small openings made with the point of the pick, and, in skilful hands, they serve to loosen ground of very dense texture.

The miners' shovel, fig. 4, has a pointed form, which is necessary to make it possible to force it into or under the coarse and hard fragments of which the waste from a mine principally consists. It is furnished with a long handle somewhat bent, by which a man's power is applied in the most convenient form without stooping the body.

The tools for blasting, or, as it is technically called, shooting, consist of the

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upper end with the iron sledge or mallet, fig. 7. The hole is occasionally cleaned out by the scraper, fig. 11, which is an iron rod turned up at one end; or if the ground is very wet, and the hole fills with mud, a stick beat at the extremity till it forms a kind of brush is used, and is called a swab-stick.

Holes for blasting are generally about one inch and a quarter in the bore, and of various depths from ten or twelve inches to three feet; but these, as well as the position and direction in which they are bored, and the charge of powder employed, are subject to the skill and discretion of the miner. The rules by which he is guided are to direct the effort of the explosion to a part of the rock which is most easily displaced, and to proportion the charge to the effect required, so as to shake and loosen a larger portion rather than to blow out a less quantity.

Fig. 6 serves to explain the process of blasting, and represents a section of a hole ready for firing. When the hole is bored it must be made as dry as possible; to do which it is partly filled with good tenacious clay and a round iron bar, nearly fitting the bore of the hole, but somewhat tapering, and called the claying-bar; this is driven in with great violence, which so forces the clay into all the crevices of the rock, that, when the bar is withdrawn, the hole usually remains dry. Where this plan fails, from the great flow of water all round, it becomes necessary to use tin cartridges furnished with a stem or tube through which the powder may be inflamed. À section of one of these cartridges is shown in the plate, fig. 13.

When the hole is dry, either by clay, or otherwise, the proper charge of gunpowder is introduced, and the nail, a small taper rod which ought to be made of copper, is inserted, and reaches to the bottom of the hole; the hole is then ready to receive the tamping, which is the most difficult and dangerous part of the process. It is by this that the gunpowder is confined, and the effect produced; different substances are in use for ramming into the hole for this purpose; that most usually employed is any soft kind of rock, which is free from quartz or flinty matter. Small quantities at a time are introduced into the hole, and rammed very hard by the tamping bar, which is held by one man, and struck with a sledge by another; this is continued until the hole is filled up, and the nail being then drawn out by putting a bar through the eye, and striking it upward, leaves a small perforation or vent for the rush which conveys the fire.

The danger of beating the tamping with iron tools in hard rock, and the many dreadful accidents that frequently happen in this operation, have led to the introduction of contrivances to diminish the risk; but, though some of these have been well adapted for the purpose, yet, as they occasion a little more trouble, they have not been generally adopted by the miner. The simplest and best precaution against danger is to have the nail of copper instead of iron; but, as the former is not so easily made or repaired by the smiths on a mine as the latter, they are not so well liked by the workmen.

The other mode of preventing danger in tamping is by employing substances to confine the gunpowder which require little or no force in beating them into the hole, and as dry sand will often serve the purpose if the rock is not very hard it may be sometimes used; but there are many cases in mines where it will not succeed, and therefore it is seldom attempted. A better substance to confine gunpowder in holes is good. tough clay, and this will answer in many cases where sand will fail particularly in wet ground, or in holes that are inclined upwards, it will produce the proper effect in all but very hard rocks, and, if the men could be induced to use it, would undoubtedly tend to the saving many lives.

When the tamping is completely rammed in, and the nail drawn out, a small vent or touchhole remains, which is to receive the rush to communicate the fire. Any small tube filled with gunpowder will answer for this purpose, but nothing is better or more easily prepared than those in common use. For this purpose, the green rushes which grow in wet marsh lands are chosen, and are selected as long and large as can be had. By making a slit in one side, and drawing along in it the sharp end of a piece of stick, the pith may be taken out very completely, and from the elasticity of the skin of the rush the slit closes again. To fill this tube with gunpowder, the rush is held in one hand so as to pass through a small quantity of powder retained in the palm of the hand; and by opening the slit with a small wedge, and pushing the rush along through the powder at the same time, it is made to embrace a quantity sufficient to communicate inflammation.

To fire the hole, one of these charged rushes is dropped through the vent, and is made steady by a piece of clay; a paper snuff is then fixed to the top, which is so adjusted as to burn a sufficient time to permit the man who fires it to retreat to a proper distance.

Fig. 6 represents a section of a charged hole in a rock. The portion which would be dislodged by the explosion is that part included between A and B. The charge of powder is shown by the white part, which reaches as high in the hole as C: from that point to the surface of the rock the hole is filled with tamping, excepting the small orifice which contains the rush, and which has the snuff affixed at D.

Fig. 14 is a drawing of a wheelbarrow, such as is used under ground for conveying ore and waste to the shafts: these barrows are very simple in their construction, and adapted to the narrow and low levels through which they have to pass. They are usually made all of deal, this timber being the most fitted to the purpose. The wheel has a narrow band of iron round it.

Fig. 5 is an iron bucket, or, as it is called in Cornwall, a kibble, and is used for holding the ore and waste while it is drawn up the shafts by machines, worked by horses, called whims. Kibbles are generally made of wood, having very stout staves, very strongly bound with heavy iron binds or hoops; but as those made with iron plates are to be preferred, and need not much, exceed the others in weight, we are glad to be

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