This is the germinal idea from which sprang the submarine mine or torpedo; and the first design for a submarine boat was also produced by the English Navy in the same generation. The author of this was William Bourne, who had served as a gunner under Sir William Monson. His invention is described in his book of ‘Inventions or Devices’ published in 1578, and is remarkable for its proposed method of solving the problem of submersion. This is to be achieved by means of two side-tanks, into which water can be admitted through perforations, and from which it can be blown out again by forcing the inner side of each tank outwards. These false sides are made tight with leather suckers, and moved by winding hand-screws--a crude and inefficient mechanism, but a proof that the problem had been correctly grasped. For a really practical solution of this, and the many other difficulties involved in submarine navigation, the resources of applied science were then hopelessly inadequate. It was not until after more than three hundred years of experiment that inventors were in a position to command a mechanism that would carry out their ideas effectively. The record of these three centuries of experiment is full of interest; for it shows us a long succession of courageous men taking up, one after another, the same group of scientific problems and bringing them, in spite of all dangers and disasters, gradually nearer to a final solution. Many nations contributed to the work, but especially the British, the American, the Dutch, the French, the Spanish, the Swedish, the Russian, and the Italian. The part played by each of them has been, on the whole, characteristic. The British were the first, as practical seamen, to put forward the original idea, gained from the experience of their rivalry with Spain. They have also succeeded, at the end of the experimental period, in making the best combined use of the results of the long collaboration. A Dutchman built the first practical submarine, and achieved the first successful dive. The Americans have made the greatest number of inventions, and of daring experiments in earlier wars. The French have shown, as a nation, the strongest interest in the idea, and their navy was effectively armed with submarines ten years before that of any other Power. To them, to the Dutch, and to the Italians, the credit belongs of that indispensable invention, the optic tube or periscope. The Swedes and Russians have the great names of Nordenfelt and Drzewiecki to their credit. The Germans alone, among the eight or nine nations interested in the science of naval war, have from first to last contributed almost nothing to the evolution of the submarine. The roll of submarine inventors includes about 175 names, of which no less than 60 belong to the English-speaking peoples, but only six to Germany. Among these six, the name of Bauer is remembered as that of a courageous experimenter, persevering through a career of