Each submarine carries from one to six torpedoes, each of which is capable of sinking the most heavily armored vessel afloat.  The sighter in the conning tower moves swiftly, up within range of the vessel he is attacking and gives the signal for the discharge of the torpedo.  The men aboard the attacked ship have no warning of their impending death except a thin sheaf of water that follows on the surface in the wake of the submerged torpedo and which lasts only an instant.

RUN BY COMPRESSED AIR

By a compressed air arrangement motive power is furnished the torpedo in transit for its propellers.  A gyroscope keeps it on a plane and upright.  A striker on the nose of the torpedo is released by a fan which revolves in the water.  The nose of the torpedo strikes the side of the battleship and the compact jars the primer of fulminate of mercury.  The high explosive of gunpowder forces out a shell and exploded with it after the shell has penetrated the armor.  Then the work is done.

It is generally believed the principal harbors and fortifications in England are heavily supplied with torpedoes of the new type.  It is also believed that the fortifications about the River Elbe are thus equipped.  If this is a fact the defending nation will be able not only to repulse any fleet attempting an invasion but also to destroy it.  By throwing across the Straits of Dover, or across the lower end of the North Sea, a flotilla of its powerful submarines England can prevent any naval invasion of France or England or Belgium by Germany should the attacking fleet take this route.

In the latest type of submarine the United States is deficient.  There are only twenty-nine submarines in the United States naval service at the present time and only eighteen under construction.

The old type of torpedo did not have penetrative power [Illustration:  Cross section of Belgian Type of Fortress.  The forts at Liege were of this type and long withstood the battering of the German guns.

This kind of modern fort was designed by the famous Belgian military engineer, General Brailmont.  The strength of every such work must depend on the spirit of its garrison, and at Liege and Namur, the Belgian defenders gave a good account of themselves.  These forts are provided with an elaborate system for repelling attempts to carry the works by assault and for making a counter-attack.  There are land-mines, fired electrically from the forts, wire entanglements, disappearing guns, and search-lights to locate and blind an attacking enemy.]

[Illustration:  Construction of Modern Torpedo, Showing All Important Parts, Including Engine, Propellers, Steering Gear, etc.] sufficient to sink the modern armor-clad battleship unless it struck under exceptionally favorable circumstances.  A large percentage of the destructive power was expended on the outside of the hull.  Commander Davis of the United States navy invented the torpedo that carries its power undiminished into the interior of the vessel.