Page:Popular Science Monthly Volume 88.djvu/234

 Underground Engineering at the Front

���A subterranean passage connecting two distant French trenches. Such is the danger o being shot by enemy sharpshooters while passing from one trench to another, that long ^2"^" municating tunnels are dug. Sappers start from both ends, and meet in the middle. The illustration shows the first connection between tunnels which have been begun a considerable distance apart, and which are about to be united

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