(4) To fit the ships with wireless ears which will detect the presence and determine the position of the submarine before it gets within torpedoing range and so give them a chance to escape.
(5) Any number of other impracticable schemes.
Now, you may ask why these schemes are useless. Among the reasons are these, (a) steel armor has yet to be made that will withstand the violent explosive power of the torpedo, (b) ships with a draft light enough and a speed great enough to get out of the way of a torpedo could not be used as freighters, (c) nets on ships make them slow and unwieldy, and as soon as they were used the torpedoes were fitted with steel cutters which enabled them to go through as easily as before, (d) the art of wireless has not yet advanced to the point where it is possible for a ship to detect the presence and position of a submerged submarine, (e) every other scheme that has been put to the acid test has had a glaring fault in it.
=Plans for Destroying the U-Boats.=—Now, the right way to break the German blockade is to destroy the U-boats, and plans along this line have been devised and carried out with better success.
The submarine can be destroyed in several ways. Among the most important are (1) by laying mine-fields; (2) by arming merchantmen with rapid-fire guns; (3) by destroying the base-ships which mother the submarines; (4) by hunting them down with submarine chasers, and (5) by dropping bombs or shelling them from aircraft.
_Laying Mine Fields in Harbors._—This plan is very good for protecting harbors against submarine attacks; but as nearly all the merchantmen are sunk from 200 to 300 miles off the coast, the use of mines for the protection of shipping is very limited.
_Arming Merchantmen with Guns._—Arming merchantmen has met with some success, but as a matter of fact it is a very uncertain means of protection, and the large number of armed ships which are sunk weekly shows that the plan is weak.
As a merchantman, or freighter, is usually a slow craft, and a submarine can easily out-maneuver it even when the submarine is on the surface, and when she is submerged she cannot be seen, it must be clear that ordinary rapid-fire guns cannot easily hit her.