There are many who believe that the submarine is limited in its power because of the inherent nature of its operation. These are the people who erroneously conceive that the submarine designers in some peculiar and miraculous way manage to get around the laws of the universe. They think that the activity of the submarine is in defiance of the law of gravitation; that it performs unnatural feats. People with such views, of course, are inclined to believe that the submarine by now must have reached the height of its development, and that in any case it is an unreliable mechanism. Criticism from such sources is worthy of notice solely because of its positive stupidity. Inventors never perform miracles and they never defy nature. Man can never master nature nor override her dictates. The inventor, rather, is one who comes to know the laws of nature with intimacy, and devises ways to turn them to his use. He works in harmony with nature, perhaps a little more closely than ordinary men; the secret of inventors' successes lies in the fact that they are those who best know how to coöperate with nature. Just so the submarine, as we have seen, acts in response to the laws of gravity, hydraulics, pneumatics, and other natural sciences, and is in complete accordance with nature's dictates; it has no limitations set by nature upon its operation. Objectors on these grounds are in the same class with those who asserted some years ago that an iron ship could not float. [Illustration: DIAGRAM OF THE "ARGOSY AND ARGONAUT III" Sketch showing the submarine "Argonaut III" on the bottom and operator in diving compartment inspecting the waterbed through the open diver's door.] There is also a very numerous class of persons who hold that the submarine is a very risky and dangerous mechanism; they feel that the principles of its operation have not yet been brought to a point of safety or certainty. The facts upon which they base this judgment are found by them in the accounts of the many accidents which have occurred to submarines in recent years. As a matter of fact, these accidents have been due, as a rule, to either of two causes; namely, faulty construction or carelessness. There is not a case on record of a properly constructed, well-handled submarine coming to grief through any cause related to the principle of her operation. The principles of successfully navigating under the water were discovered twenty years ago, and have been applied with perfect safety ever since. Many designers since that time have failed to recognize the correct principles, and their incorrectly built boats have given trouble; hence accidents have occurred. To-day, however, the true principles of construction are universally recognized. The modern submarine has passed the stage of experimentation.