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Show "Ml Hi I r V A K :fWCW r-ti S7 111 II 8 b$4 .h rr- Htjx XM ftAx$&?i - mi) ,,,,,, w. jZ&isitvJk jeS A LTHOUGH it Is only recently 'A and with reluctance that Eng-J Eng-J U land, for the protection of her '3""vA shores and ships, has (in iml liy- tatlon of the Germans) resort- ul5'"Ty ed to the expedient of sowing ii- lT the Straits of Dover and the North sea with contact mines, t : ? all the harbors of the British is Isles have been planted with i WjM submarine explosive contriv- sEJ ances ever since the beginning TI13" of the war. And the same may be said of the harbors of Germany. But these contrivances for harbor defense, while much more formidable and dangerous to an enemy, are. harmless to friendly Ships. They are what -are known as "observation mines," and, being connected con-nected by wire with the shore, are set off by the sending of an electric spark at a moment when a hostile vessel may happen to be within range of their tremendous explosive activities. All the navigable channels of the harbor of Portsmouth, for example, are at this moment guarded by an elaborate system of "mine fields," which are protected by rapid-fire guns on shore. At night they are under constant watch, as well as by day, being swept by huge searchlights. Such mines are hollow spheres of galvanized iron three feet in diameter, each containing 500 pounds of guncotton, which is lighter than water, so that they can float. They are anchored a few feet below the surface in a series of lines across a channel, about eighty feet apart in each line. If an enemy's ship were to succeed by good luck In getting through one line without being blown up, she could hardly pass another. The area of water surface covered by a mine field is laid off (by careful Biirvey) in a checkerboard checker-board of imaginary squares. This checkerboard is reproduced on a small scale on a table in an underground un-derground casemate on shore, which is part of a fort. Suppose a hostile vessel to approach Two telescopes are aimed at her from points on shore some hundreds of yards apart, their lines of sight crossing, of course, at the spot where she floats The telescopes are electrically connected with two pointers that move on the table. Moving with the . telescopes, the ends of the pointers meet on the square corresponding to the one where (over the mine field) the vessel actually is. A button marked mark-ed with the number of that square is touched, and tiang! she is blown sky-high. ' Small steamers especially equipped for the purpose pur-pose are used in the business of planting these mines, and the work being of such great Importance, Import-ance, the men who undertake it are highly trained Theirs is a branch of the coast artillery which does its fighting literally under water, and, apart from the mechanical details of their employment, they n.ust have a fairly expert acquaintance with electricity and the chemistry of explosive i. A part of the preliminary work of establishing a mine field consists in making soundings. Thu depths all over the surveyed area having been ascertained, wire ropes are measured off into cor responding lengths, a heavy leaden sinker (or anchor) being attached to ore end of each, and a mine to the other end. By this simple means the sphere of galvanized iron is made to float just as many feet below the surface as may be desired ' Recently, however, an Ingenious "automatic anchor" an-chor" has been contrived, by which, no matte;' what the depth, exactly the required submergences for each submarine may be obtained offhand. As yet experience In actual warfare has not afforded practical demonstration of the usefulness of such observation niinos. Put of their destructive destruc-tive power there can be no question. Many experiments ex-periments have been made with them in the blowing blow-ing up of old hulks, and on this side of the water not long ago, a miniature ship of war was scat tered in smithereens at Fort Totten, N. Y., by a mine of corresponding size ignited by an electric spark from a distance pf a mile and a quarter. From such trials the conclusion has been drawn that the explosion of a mine containing lino pounds of guncotton would at least disable the stoutest battleship within a radius of fiO feet, if it did not sink her. In a "field" defending a harbor channel, each row of galvanized iron spheres Is strung along one electric cable, which is attached to 'tie sinkers (or anchors) nnd runs along the bottom The row 8 are connected together by a main elec trie cable, to which each mine is joined by a branch cable that meets it just above the anchor Thus every mine In the "Held" Is under dire-t control by the apparatus in the casemate on shore The ' casemate is an underground room, lind with concrete, and containing all the mechanism for controlling the mine system. It is connected by telephone, and otherwise electrically, wi:h the two observing stations, in which are mounted tn? telescopes already mentioned, for watching lipstih? ships. Sometimes, for the protection of hnrhorr.. what are called "electro contact" mines are tied Th -v are much smaller in size, and are commonly ir ranged In groups of five or six. which are con contrivance used by the Germans is called (after its originator) the Schwartzkopf meaning Blackhead. Black-head. They differ only in minor details, being shaped in imitation of the porpoise, and fired from tubes by charges bf compressed air. The typical up-to-date torpedo ,of this' descrip-. descrip-. tfon is really a submarine boat in miniature, it Is a steel cylinder, 15 feet long, with a conical attachable nose called a "war-head," which con tains 200 pounds of high explosive. The main body is a chamber holding air at a pressure of 2,000 pounds to the square inch. This air pressure runs the machinery In the rear part of the cylinder, cylin-der, which actuates a pair of propellers. The steel fish travels through the water at a speed of 40 miles an hour. It can be discharged at a target with as much accuracy as a bullet fired from a gun. Pursuing Its course at a depth of 15 feet below the surface, so as to strike beneath the armor of a warship, it is kept automatically at that depth by an ingenious little rudder which turns up If the nose of tfie torpedo attempts to point downward, or vise versa. Inside the cylinder Is a gyroscope, which is started spinning and pointed at the target before the submarine projectile projec-tile is discharged. Thus, jf it tends to turn either to right or left, it is promply brought back Into line. Until within the last few weeks very little was known through practical experience of the effectiveness effec-tiveness of the submarine torpedo as a weapon of war. It has even surpassed expectations. The cost of one of these terrible projectiles is about $1.B00; but. inasmuch as one of them Is easilv capable of destroying a battleship valued at $10-fOO.OOO, $10-fOO.OOO, they may be said to be well worth tho money. nected with each other and with the shore by one main cable. It is only when a current of electricity elec-tricity is turned on that they become dangerous; under other circumstances they are "dead" and harmless. But when they are "alive," if a ship hits them, a circuit is automatically closed and the water is quickly strewn with her remains. Various Vari-ous ingenious means have been devised for bringing bring-ing about this closing of the circuit, one of them being a little cup partly filled with mercury, which, if tilted by a shock, causes the mercury to reach a metal bar. This does the business, and bang goes the mine. It is interesting just now to consider the fact that the very first employment of a floating mine was at the siege of Antwerp by the Spaniards !n 1585. The besiegers, being able to make little or no headway in their attacks upon the stout walls of the city, resorted to a novel and unheard-of stratagem. Loading a ship with a great quantity . of gunpowder, they set her adrift at a time when the wind and tide would surely bring her up against the sea wall; and. when she was tolerably close, two men on board of her ignited a pre viously arranged fuse. The idea worked out, however, In a way not at all in accordance with the plan contemplated. For the sturdy burghers of Antwerp repaired the damage done to the wall by the explosion before the besiegers could take advantage of it, and, adopting the suggestion offered them by the enemy, en-emy, sent out a sintilar gunpowder boat under full sail against the Spanish fleet and blew up one of their biggest ships. In recent news dispatches a good deal has been said about the use of mines on land, for the opportune oppor-tune blowing up of bridges or approaches to fortifications forti-fications while the enemy was passing over them. By such means whole regiments are said to have been annihilated. The expedient is by no means new. but the methods adopted are of up-to-date and superior ingenuity. Suppose,' for example, that a piece of road Is co be mined. The infernal machine is concealed from view by spreading over It a few Inches of earth. In consists in part of a small electric batte.-y provided with two wires, one of which communicates communi-cates with a receptacle containing a large quantity of high explosive, while the other runs to an ar rancement called a "f princboard." When a man or horse steps on the springboard, a piece of metal beneath the latter Is brought Into contact with a projecting pin. thereby completing a circuit which ignites a fuse The same idea is easily applied to a bride? In the case of a fort, a system of more scientific ally constructed minps may render every approach a waiting volcano, a switchboard inside the defenses de-fenses enablins !) besieged to explode them at the moment when thry are likely to kill the greatest great-est number of men. Iu modern warfare wholesale killing takes the place of the old fashioned military murder by retail re-tail Doubtless, as time goes on, "Improvements" in this direction will steadily progress. The British Brit-ish and Germans have both been experimenting with means whereby (it is hoped) submarine mines may be set off by wireless apparatus. They are also trying to contrive a submarine "fish tor pedo" (resembling the Whitehead) which can be steerrd from shore to attack a hostile ship perhaps per-haps miles from land The Whitehead is an Englishman's Invention, and is the only kind of fish torpedo used in th? British navy Oddly enough, the similar devil's |