Minesweeping

“ Some of the new features were the development of depth-charge throwers, the manufacture and use of fast coastal motor-boats for anti-submarine work, the production of mines of an improved type for use especially against submarines, very considerable developments in the use of minefields, especially deep minefields, including persistent mining in the Heligoland Bight and the laying of a complete minefield at varying depths in the Straits of Dover; also, after the United States entered the war, the laying of a very extensive minefield right across the northern part of the North Sea. ”

“ The very act of thus dragging it along by its anchor rope often causes a mine to explode, well astern of the mine-sweeping vessels, but sometimes they are pulled up and fired or sunk by a shot from a gun which the sweeper carries for the purpose.
The sweeping up of the mine-fields is a duty often allotted to the steam fishing boats or trawlers, whose crews seem particularly well fitted for the work. It is a hazardous duty, and many lives have been lost through it. ”

“ The formation usually adopted by British minesweepers [170] was that shown in Fig. 28, in which it will be observed that each pair of ships is actually independent of the others, but is acting in company with them, and that the pathway swept by one pair is slightly overlapped by the following pair. In the event of an accident to one ship the next astern can immediately let go its own end of sweep-wire and go to the rescue of any survivors. It may be apropos to say here that the smaller class of minesweeper is usually blown to pieces if she touches a mine. ”

“ They explode immediately on being struck by a passing vessel, and, of course, do not discriminate between friend and foe. The systems of destroying hostile mine-fields consist of counter-mining, or placing other mines in the enemy’s field and destroying it by 170their explosion, and by sweeping. The latter method is the one mostly employed in modern warfare. The boats taking part in the sweep place themselves one on each side of the mine-field, and between them hangs a long wire rope, weighted in the centre to keep it well submerged. ”

“ Or we might say that sapping is under-mining, in which sense we use it in general conversation when we speak of something sapping a man's strength. Soldiers speak of their engineering comrades as "sappers" just as they term artillerymen "gunners," but the only reason why they call them by that name instead of miners is because the latter is a well-known term applied to those who work in coal mines.
A subterranean mine, then, is nothing more or less than a hole in the ground, made in any way that may be convenient, filled with explosives and fired at a suitable time to do damage to the enemy. ”

“ Land mines are placed in the line of the advance of the enemy and exploded either by electricity or fuse from the defense. They are made by digging holes from 2 to 3 yards deep, either by excavation or by boring. ”

“ Although the metal miner is subjected to fewer accidents than are his brethren working in coal mines, the atmosphere in the former is far more destructive to human life. In lead mines, the duration of life averages scarcely more than thirty-two years, and in those containing arsenical pyrites or quicksilver ores, the average is still lower. Before the use of gunpowder in underground operations, the rocks containing the ore were attacked with fire, indeed the practice is still retained in some countries. ”

“ Where appreciable current exists, a heavy sea may cause mines to step along, or “migrate”—there is no telling how far—and the danger from mines adrift is naturally greater near a minefield than elsewhere. Mines are designed to become safe on breaking adrift and many of them are, but far from all. Submergence in salt water may derange the mechanism for that safety purpose. There was very little current across Area A, however, and the fine tactical qualities shown by the squadron lent confidence that it could be safely conducted much nearer to our minefields than five miles. ”

“ If they stopped for a moment they could hear everywhere around them, some nearer, some farther off, the sounds of their companions burrowing away in all directions in the inside of the great mountain—some boring holes in the rock in order to blow it up with gunpowder, others shoveling the broken ore into baskets to be carried to the mouth of the mine, others hitting away with their pickaxes. Sometimes, if the miner was in a very lonely part, he would hear only a tap-tapping, no louder than that of a woodpecker, for the sound would come from a great distance off through the solid mountain rock. ”

“ The most remarkable advance, which in recent, or perhaps in any, times has been made in the practice of mining consists in the substitution of machine for hand labour in rock boring. The importance of this change is obvious, and very great. Not only is the miner relieved thereby of the labour of boring, but the speed with which the shot-holes may be bored is increased a hundredfold. This gain of speed offers many practical advantages. The ability to sink a shaft or to drive a heading rapidly may ensure the success of an undertaking, and save indirectly the expenditure of large sums of money ”

“ When the men get out of the skip down in the mine, there are many different roads in it, and each man has to go to his own part to work. When he reaches his place he has to drill holes in the rock for the dynamite which breaks up the rock, and the loose stones are taken away along the roads to the lift and then up to the top. There it is stamped with great hammers into dust, and washed, until the gold-dust is separated from the rest. There are thousands of men, both underground and at the top, always at work at the mines. ”

“ Submerged mines are more dangerous to the enemy because they cannot be seen and avoided. They should float far enough under the surface to remain hidden and yet not so deep that a shallow-draft ship can pass over them without hitting them. As the sea bottom may be very irregular, it is impossible279 to tell how long the anchor cable should be without sounding the depth of the water at every point at which a mine is planted. ”

“ Miners—hundreds of them—were brought from neighboring mines, and they worked night and day on two-hour shifts, clinging to the sides of the shaft as thick as bees in a hive. Others, risking their lives with every stroke of the pick, dug away at the earth and rock that had fallen on the big chunk of machinery. With all the speed that human effort could compass, it was six days and nights before a hole had been made through the obstruction big enough for a man to pass. ”

“ Countless, also, are the dangers to which they are exposed. To accidents as they come down or go up the shafts by the breaking of ropes, or the giving way of machinery, from the falling in of the roof or walls, as also from accidents in blasting, from spontaneous combustion, from explosion of fire-damp, suffocation from choke-damp, and eruptions of water, and even quicksands. Sometimes floods or heavy rains find their way down unknown crevices into the pit, where the miner is working, and forming a rapid torrent, suddenly inundates the mine and sweeps all before it. ”

“ Counter-mining.All mines, especially those with electric cables attached, must be protected by gun fire or guard boats, as, if the mine field is un protected, they can be easily destroyed by countermining or creeping. Countermining is carried out by exploding a succession of charges in an enemy's mine field. Mines containing heavy charges would be used for the purpose, several of these mines being dropped in succession from a boat towed by a fast steamer, the whole line being exploded together as soon as the last mine had been dropped. ”

“ Imagine the descent into a mine through the sea, the miners working at the depth of 12 fathoms below the waves; the rod of a steam engine extending from the shore to the shaft, a distance of nearly 120 fathoms; and a great number of men momentarily menaced with an inundation of the sea, which continually drains in no small quantity through the roof of the mine, and roars loud enough to be distinctly heard in it.” Tin is the principal produce of this mine, and the ore is extremely rich. ”

“ In their long journeys, the putters stop to “bait,” and are well supplied with bread and cheese, and bacon, and cold coffee or tea.
The miner has not only to fear choke or fire-damp, but sometimes water. A mine has, therefore, to be drained. A well or tank is dug in the lowest level, into which all the springs are made to run. A pump is sunk down to it through a shaft with a steam engine above, by which all the water is pumped out.
It may be seen that the working of a mine requires the very greatest care. If this is not taken, the roof may fall in and crush the labourers ”

“ The Towfikia steamer went up to Giraffe, and as the Arabs had a sort of sneaking affection for the place, we put down twenty self-exploding mines, to deter them from going there. The worst of it is, our domestic matches have run out, and we cannot make any substitute, so we have to fall back on the powder-hose, connecting groups of ten. I think good wire entanglements, with mines, will defend any place, if one has anything like moderate troops behind the parapet. ”

“ Night after night I lean over the bow and watch the phosphorescence flare and flash beneath the surface, the disturbance of the steamer's approach springing a myriad of these floating mines, whose explosions, gentler than those of human make, merely vibrate into a splendor of visibility. How to capture these tiny beings which the eye can scarcely resolve is a matter far more difficult than the netting of the seaweed. ”

“ The mine is like a large quarry, with a number of small excavations which fill with water, and are pumped by most ingenious Chinese pumps worked by an endless chain, but there are two powerful steam pumps at work also. About four hundred lean, leathery-looking men were working, swarming up out of the holes like ants in double columns, each man carrying a small bamboo tray holding about three pounds of stanniferous earth, which is deposited in a sluice, and a great rush of water washes away the sand, leaving the tin behind, looking much like "giant" blasting powder. ”

“ A gold mine now consists of a shaft or pit dug several hundred feet down into the rock, with levels or galleries running off from it and with big openings like rooms made where the rock was dug out. The roofs of the rooms are supported by great timbers. To break away the rock, the miner makes a hole with a rock drill worked by electricity or compressed air, puts powder or dynamite into the hole and explodes it. The broken rock is then raised to the surface and crushed in a "stamping mill." Here the ore is fed into a great steel box called a "mortar." ”

“ Mines of any kind are exceedingly difficult to render efficient when the water is over 100 feet deep. On account of the tendency of all high explosives to detonate by influence or sympathy, and the liability of the cases to collapse by great exterior pressure, harbor mines are separated a certain distance, according as they are buoyant or ground, and according to the nature of the explosive.
Five hundred pounds buoyant gun-cotton mines require 320 feet spacing. ”

“ When the crater radius is equal to the line of least resistance, the mine is termed common; when this radius is greater than the line of least resistance, the mine is termed overcharged; and when the radius is less, undercharged. A mine of small dimensions, formed by sinking a shaft in the ground, is termed a fougasse. The term camouflet is applied to a mine used to suffocate the enemy's miner, without producing an explosion. Small mines made in rock or masonry, merely for the purpose of excavation, without any considerable external explosion, are called blasts. ”

“ In some of the dark and dusty chambers which open here the miner's pick is heard, and now and then the muffled report of the miner's blast comes echoing through the vaulted aisles.
"But this is not the station where we are intended to stop. Our car moves on, and we plunge through two hundred feet more of the rocky rind of the earth. Above us the mouth of the shaft seems narrowed into an insignificant hole; before us opens a dark street, over which, on a tramway, mules are hauling carloads of coal, which is starting on its way to the surface. Miners with picks are moving to and fro ”

“ Bored mines, which have been alluded to above, are a comparatively recent innovation. When the enemy is heard at work in one of his galleries and his position approximately determined by the sound, it is necessary to drive a branch gallery with all speed in that direction, and when it has advanced as far as appears necessary, to load, tamp and discharge a mine before the enemy can fire his own mine. ”

“ Another of our staff is the officer in charge of our 'Otter' installation, an ingenious contrivance to protect us against the menace of moored mines. For deadly spheres floating on the surface we have a certain measure of defence in exercise of a keen look-out, but our eyes avail us not at all in detecting mines under water moored at the level of our draught. Our 'Otters' may be likened to blind sea-dolphins, trained to protect our flanks, to run silently aside, fend the explosive charges from our course, bite the moorings asunder, and throw the bobbing spheres to the surface. ”