164 



Popular Science Monthly 



balloons must be many" times larger than 

 the heaviest floating mines. At short 

 range they would furnish ideal targets 

 to a Zeppelin's machine- 

 guns. A Zeppelin may 

 easily shade its lights 

 and yet clearly illumin- 

 ate a near object 

 in the air. Let 

 a good marksman 

 with a machine- 

 gun be stationed at each 

 side of the front car, and 

 before any balloon-mine 

 could do any harm, it 

 would be shot' down and 

 fall into a city street. 



The Plan Is Feasible in 

 Water 



Interconnecting cables 

 such as Mr. Steinmetz 

 proposes, are more satis- 

 factory in water than in 

 the air, where they are 

 liable to slip off upward 

 or downward. If caught 

 by airships below them, 

 the bombs will be drawn 

 together harmlessly be- 

 neath the level of the 

 hull. The chances are 

 that the Zeppelin would 

 gather a trailing mass of 

 wires, empty balloons 

 and live bombs in its 

 wake, to be cut off for 

 the benefit of those be- 

 low. The steel propel- 

 lers would cut the thin 

 wire, and since they are 

 as big and heavy, would 

 hardly be damaged. It 

 would also be easy to 

 shape a Zeppelin so that 

 single wire must slip off 

 wherever it strikes the 

 hull, simply by slanting 

 the outlines of all pro- 

 jections. 



It does not look as though the Stein- 

 metz plan would make Zeppelin destruc- 

 tion assured. The three dimensions of 

 the air necessitate the use of mines in 

 large numbers, yet the risk is propor- 

 tionately increased. Here comes the ques- 

 tion of the practical value of the plan. 



/ 



Hooks and flaming bombs as 

 a terror of the air for Zeppe- 

 lins and, indeed, for any den- 

 izens of the air. But is the 

 terror not as great for the 

 houses below? 



Sweeping a Channel for Mines 



THE operation of mine sweeping is 

 one of the most dangerous and 

 arduous of the 

 many tasks that 

 fall to the lot of 

 a navy. The dan- 

 gers of mine 

 sweeping are 

 great even in the North 

 Sea and around the Brit- 

 ish Coasts, where there is 

 no active opposition. 

 These dangers are, of 

 course, greatly increased 

 when the ships are con- 

 tinually under fire, as 

 they were in the Dardan- 

 elles. 



A mine field consists 

 of a number of mines 

 laid together. It will most 

 effectively block off any 

 particular area of water. 

 A certain number of 

 mines are generally laid 

 at intervals just deep 

 enough to render them 

 invisible to the look-out 

 on board the mine sweep- 

 ers. For such work shal- 

 low draught ships are al- 

 ways employed. 



Mine sweepers work 

 generally in pairs. Each 

 ship tows over the stern 

 a wooden apparatus called 

 a kite, fitted with planes 

 which dive beneath the 

 water. The depth to 

 which it dives is regu- 

 lated by the speed of the 

 towing ship. Each of 

 these kites is fitted with 

 a pulley block. A wire 

 rope is passed from the 

 stern of one ship through 

 the pulley on its own kite 

 across the water through 

 the block on the second 

 kite and so up to the stern of the second 

 ship, where it is fastened. Both ships 

 steam ahead at the same speed, the kites 

 dive to the depth corresponding to the 

 particular speed, and the steel rope is 

 stretched out between them. When the 

 rope strikes a mine, it fires it. 



