COAL-CUTTING MACHINERY.
We have often heard miners say that it would be impossible to substitute machinery for their labor in cutting coal, and that their trade or occupation could not be interfered with by modern inventions. We cannot understand the desire of the coal-miners to monopolize their laborious and dangerous employment; and we think that any im provement or invention that would lighten their labors must prove a blessing to them instead of an injury. In their case, as in that of all others, any substitution of ma chinery for manual labor not only lightens their burdens, but adds to their pay and increases the sources of employment. If machines were introduced to do the "holing" or undermining, it would cheapen and increase the production of coal.
It is not probable that machinery will be produced to mine coal in our white ash blasting-seams; but, for the purpose of mining or holing—"kirving," as the Eng lish miners say—in bituminous coal-seams, they are already successfully at work in several of the English collieries. The plan is very simple, and available in hori zontal seams, or in those having a gentle dip; while it may be used in seams of con siderable pitch.
There are two modes in use, both as to the means of giving motion and the character of the motion,—compressed air or steam in the first, and the circular motion or thrust in the second. We think compressed air with the thrust motion is the best, since the use of air adds to the ventilation of the mine when below water-level, and particularly in deep and fiery mines, while the thrust motion dispenses with the necessity of com plicate machinery.
Air is condensed by a stationary engine placed at the top of the mine, or by an attach ment to the rods of the pump, and is confined in appropriate reservoirs in convenient parts of the mine, to which it may be conveyed by pipes; or portable air-cylinders on wheels are filled by the air-pump, and conveyed to the breasts or chambers by the ordi nary roads used by the coal-cars. The machine for cutting coal is variously made, but the one which we think most simple and perfect is a plain cylinder, with a thrusting bar or pick attached to the piston. This is securely attached to a frame with wheels and ratchet, and is placed on a temporary track securely fastened down along the face of the coal.
When in place, the working cylinder is connected with the air cylinder or reservoir by means of a flexible tube, and the operator starts it to work by a hand-lever, as he would a steam-engine. The thrusting bar is forced forward against the coal, or in the "mining," until a fair commencement is made, and a full cut of a foot or eighteen inches obtained. The machine is then thrown into self-acting gear, and the thrusting bar or pick works rapidly, while the apparatus is moved slowly forward by a hand ratchet, or is self-acting. Each thrust of the pick takes off a thin slice of the coal the full length of the stroke, and as the machine is moved forward the "holing" is made the full breadth of the breast to the depth of the thrust, say 18 inches, by 3 inches in height. The thrusting bar is then removed and a narrower one made use of, say 2 inches in size, of cutting edge. The machine is then worked backwards, and the
second cut is made across the breast until the holing is from two to three feet deep, according to the length of the stroke. If the stroke is only 12 inches, three cuts are made, but if 18 inches, two cuts will do, unless the "holing" is required to be over three feet deep. Three feet is not a limit, however, to the "holing" by this machine, since it can be carried to the depth of five or six feet if necessary, and a cut three feet deep can be made if desired. The piston may work at the rate of 60 strokes per minute, and each cut may take off a slice of coal from one-eighth to one-quarter of an inch in thickness,—say, for example, one-fifth, which, at 60 cuts per minute, would mine 12 inches per minute 18 inches deep: consequently, it would hole 30 feet in length by 3 feet deep in an hour, and this would be the minimum duty. It can be made to double that duty by working faster and taking larger slices, depending on the power of the machine. But at the rate mentioned it would undermine 10 breasts, 30 feet wide, to the depth of 3 feet each, in 12 hours, allowing 2 hours for removing and placing the machine 10 times, which would be ample, since the operation is simple; and by having two sets of rails and racks, the breast can always be prepared for the machine in advance.
To accomplish the work done by this machine, 30 men would find enough to do, But, to be within bounds, we will say that ten men, with the aid of the machine, would do more work than thirty men without it, and with this advantage:—the heavy work is done by the machine, and its breathing, instead of vitiating the air in the mine, adds greatly to its amount and purity, particularly in the locality where used.
The illustration given in figure 12, in the early pages of this book, represents the operation of the iron miner, but the plan there represented shows the circular or crank motion. The motion of the pick is much the same as that given by the miner. It may be equally effective in operation, but the machine cannot be constructed with as much simplicity as when the direct thrust is used.
There can be little doubt of the utility of these machines for mining purposes in deep and gaseous bituminous mines, and we think their general adoption in all our bituminous mines, where the cars can be taken into the breast, is only a question of time. Our coal-miners need not be jealous of this competitor, since he will not only lighten their labors, but will extend their usefulness and the sources of their employment.
The writer knows something, experimentally, of kirving or under-mining, and can say positively that there is no more tedious, laborious, and tiresome work performed by bone and muscle. We therefore hail the advent of the " Iron Miner" as the precursor of better times for the coal-miners. We may task him without remorse and without stint: he will work in fire-damp or chokedamp without injury to constitution or strength, and will drudge with tireless activity, to the relief of the hard-working and poorly-paid " kirvers."