Minesweeper

“ A submarine mine of to-day consists of a mine case, shaped like a ball or egg, about one yard in diameter, mounted on an anchor in the form of an iron box about 30 inches square, connected by a wire rope mooring cable, about 3⁄8 inch in diameter. The mine case contains the charge of high explosive—300 pounds of TNT in our mines—and the firing mechanism. The combination stands about 5 feet high and weighs 1400 pounds. Four small car wheels on the anchor run on steel tracks, allowing the mines to be easily moved along the decks to the launching point. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ A mine, as the reader probably knows, is a cask filled with high explosives and fastened by means of weights and anchors so that it floats some feet below the surface. Mines can be planted in fields, as it were, by torpedo-boats or submarine and then a hostile fleet can be lured or chased in among them. The North Sea, as we know, is at present thickly strewn with them and fatal results have already been chronicled. Air-ships and aeroplanes can help by finding the whereabouts of the hostile fleet and designating by wireless the spots where the mines should be planted. ”

“ 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. ”

“ To assist its attrition, a rill of water keeps it constantly wet, and it is carried by a small gutter into the fore pit, where it makes its first settlement, the lighter particles running forwards with the water into the middle pit, and thence into the third, where what is called the slime, settles. From these pits the ore is carried into a large vat, called the keeve, where it is washed and rendered clean enough for the smelting house. Most of the tin mines now working have steam engines, the advantages of which have proved a great benefit to the proprietors of them. ”

“ The extent of this practice in mining will be understood from the quantity of gunpowder consumed. In the six mines, the temperature of which is given above, and the far greater part of which are situated in the comparatively soft rock killas, the expenditure of gunpowder per month, in 1820, was 8,810 lbs.; the number of men employed underground being 2323. Each charge consists of from 1⁄4 to 1⁄2 lb. of gunpowder. No means are taken to expel the smoke and irrespirable gases produced, which are left to find their way slowly to the outer extremity of the galleries and the shaft. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ Rough washing boxes, rough troughs through which we turned water, shapeless holes in the ground partly filled with water, great heaps of worthless gravel, the dismal sucking sound of the old hand pump, and a clutter of boards, pans, shovels, and picks.
Yet we had one of the few good mines down there. The “pork knockers” have no mines; they journey from place to place up [Pg 133] and down the river with pick and shovel and sieve, with a small quantity of food on their backs, and make shelter wherever they happen to be. ”

“ 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. ”

“ 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. ”

“ But the skilled North Sea fishermen who man the trawlers are the right men for this sort of work. They rapidly acquire all the tricks of sweeping, and soon learn to detect a mine that has been caught in the sweep by the singing of the sweep wire, the feel of it, and other delicate signs. The mine-sweeping trawlers are accompanied by a vessel whose duty it is to sink or explode by rifle fire the released mines as they appear on the surface. ”

“ Piled up in one corner was an outfit of miner's implements, pans, axes, spades, picks, etc., and close beside them was a sack of moose-hide. Whipping out my knife, I cut through the thongs by which the sack was tied; it lurched over, letting fall a dozen ounces or so of gold dust. On searching round, I found in another corner a second sack containing nuggets. When I went about the walls, and pushed my way into some of the tunnels, I was made certain that I was in one of the richest placer-mines that I had ever set eyes on. ”

“ They are employed for patrol work, also for mine-sweeping, but are not powerful enough for this latter work, except under certain conditions. The duty for which they are very well [194] adapted is the exploration of enemy minefields at low water, and the sinking of such moored mines as appear above the surface, as is not infrequently the case in consequence of the inaccurate laying of the mines. The German mines, I may mention, were mostly laid at eight feet below the sea-level at low water. ”

“ The Boche served us full portions of all three of these man-killers in the Warren and kept us ducking in and out pretty much all the time, night and day.
I was lucky enough after the first day to be put on sappers' duty. The Sappers, or Engineers, are the men whose duty it is to run mines under No Man's Land and plant huge quantities of explosives. There was a great amount of mining going on all the time at Vimy Ridge from both sides.
Sometimes Fritz would run a sap out reasonably near the surface, and we would counter with one lower down. ”

“ At many mines, however, the greater convenience of having the stables on the surface induces the operators to have the mules hoisted from the shaft every night and taken down every morning. They step on the carriage very demurely, and ascend or descend without making trouble. They are especially glad to go up to their stables at night. Where mules are fed in the mine, and especially in those mines that have stables in them, rats are usually found. How they get down a shaft is a mystery. ”

“ 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. ”

“ 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. ”

“ NOTES BY THE FIRST LORD Mining is mainly of two kinds, ambush mining and blockade mining.
Ambush Mining. Ambush mining depends on the whereabouts of the field remaining unknown. These mines may be scattered about in patches, or short lines in the neighbourhood of the enemy’s ports or of the approaches to your own ports or landing places on the chance of enemy ships running into them. This chance is not great. The seas are very large; the area mined, even if on a great scale, very small. ”

“ 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. ”

“ No end of mines were made by the sappers in the piers of the windows, dead walls, vaults and cellars, and in pits underground. Innumerable were the charges varying in each chamber from 15 lbs. to 600 lbs. of gunpowder. The largest charges were placed in the vaults. Always tedious were the processes; the labour in many instances considerable, and the hardships experienced were those which arose out of intense cold, snow-storms, thaws and frost. ”

“ They could also see the mine-sweepers at work, clearing the fairway from those foul nests of floating mines which the crafty foe had been busy laying with their submarines. Once or twice they thought they could make out some dark-grey object like a mine or sunken vessel beneath the surface of the water. ”

“ The miner never touches either the explosive or the detonater. Then the shot-firer puts the primed charge in the hole, jams the hole full of clay with a wooden tamper—a steel bar might cause a spark and a premature explosion—tests for gas again, connects the electric wires from a portable battery around the rib corner, fires the shot, returns to the face and tests for gas again. Then, and not until then, does the miner begin to dig the coal. ”

“ A similar sacrifice in the shape of pillars is often necessary to support the surface, either to avoid injury to valuable structures or to prevent a flooding of the mine. As already noted large pillars must always be left to protect shafts, adits and the more important mine-passages necessary for drainage, ventilation and the haulage of mineral. In the early history of mining there was but little attempt at systematic development and working, and the mines were often irregular and tortuous. ”