The majority of the British and American boats are developments from the original _Holland_ of Mr. Holland's design. Increasing the stability, greater subdivision of ballast compartments, refinements in steering gear, and the addition of hydroplanes forward have enabled Mr. Holland and his successors to produce submarines that operate very well. These boats, however, with only one pair of forward planes, still require constant manipulation of the horizontal rudder to control them when submerged. This rudder, controlled by power gear, is very effective and will, by expert manipulation, hold the submarine to practically even depth. The only danger the writer can see is that the diving rudder gear might fail to function after it is set in the diving position, in which case the vessel might continue diving until she struck bottom or reached a depth great enough to cause her to collapse. The modern submarines, therefore, as built and used in all the world's navies, owe their final success to principles of construction and control devices invented and introduced into the art by two American inventors. CHAPTER V USE OF THE SUBMARINE IN WAR The submarine boat is the guerilla in warfare. Its tactics are the tactics of the Indian who fights under cover or lies in ambush for his enemy. These are necessarily the tactics of all weaker individuals and are an essential method of procedure in preventing the weaker party from being annihilated by the strong and more powerful. Some people have contended that the submarine is an unfair weapon, but the old statement that "all's fair in love and war" applies to the submarine as it does to every weapon which has been invented since the days when men struggled for supremacy with their bare hands. The first man who wielded the club might have been accused of being unfair; the same term might have been applied to the man who invented the sling-shot or the bow and arrow. When people fight for their existence, the existence of their families or of their country, they do not fight according to the "Marquis of Queensberry Rules." A revolver in the hands of a weak man or a defenceless woman is a proper weapon to enable them to protect their property, their honor, or their life; and, no matter what theorists may claim, the submarine will remain as a weapon to be reckoned with in all future wars, provided there are future wars upon the high seas. In making this assertion I do not intend to justify a great many of the acts performed by the submarines of one of the belligerents in the present war. I do claim, however, that the submarine is a perfectly legitimate naval weapon, and that it deserves a place in the armament of any nation whose military power is maintained for purposes of self-defence.