The first submarine as a locomotive engine of warfare was invented by John P. Holland, and it is to his boat, known as the _Holland the First_, that all the modern submarines and submersibles owe their parentage. It was a one-man affair, just big enough to allow him to sit down in it and work with his feet the paddle arrangement that turned the propeller shaft. It carried five small torpedoes, which could be placed outside through a chamber in the dome or conning tower, and were discharged by electricity. This marked the introduction of one of the means which made modern submarine vessels possible, for until it was discovered how to use electricity in this way, a clockwork arrangement was the only reliable method by which a torpedo could be exploded. The application of electricity rendered it possible to eject the torpedo a considerable distance from the ship, comparatively speaking, and by means of connecting wires discharge it when thought advisable. This vessel was only 16 feet in length. The second _Holland_, built in 1877, was only 10 feet long. A small gas or oil engine was introduced to drive the screw propeller of a third submarine built by Holland two years later. This boat was 31 feet long, 6 feet in diameter, and cigar-shaped. The experiments he conducted with it showed that it was impossible to depend on ordinary vision when travelling in any depth of water on account of the darkness. She carried a pneumatic gun discharging a 9-inch projectile, the range of the weapon being 130 feet. It was not until 1884 that Holland’s fourth boat appeared. In the following year he tried again with a rather larger vessel, 40 feet long and 7 feet in diameter, often called the _Zalinski_, because it was fitted with pneumatic guns of the type invented by an American army lieutenant of that name. Again there was a long silence in regard to Holland, until he submitted the designs of his seventh boat--the sixth was planned but never built--to the American Government, which had decided to adopt the under-water torpedo boat as a definite part of the navy. The _Holland the Seventh_, as designed and launched, was to be 85 feet long, of 100 tons displacement, and to carry three torpedo tubes and two steel armoured gun turrets. The Holland Company had meanwhile designed a vessel they considered much superior, and the Government consented to adopt it in place of No. 7. She was something like a porpoise, and above a semi-cylindrical hull carried a flat-sided superstructure, which has been one of the distinguishing features of the Holland type of submarines from that day to this. Her aerial torpedo was to carry 100 lb. of gun-cotton. After discharging it she was to dive, approach the vessel she sought to destroy, and fire her Whitehead torpedo. If this missed, she was to go under the vessel and discharge her after submarine gun immediately after passing underneath. The _Holland_ was altered and improved, and when the French announced