In 1634, the same year in which Van Drebbel died in London, there was published a book entitled, “Hydraulica Pneumatica,” containing a chapter “De nauibus sub aqua natantibus.” This interesting work was written by a noted French theologian and philosopher, Marin Mercenne (1588–1648), a member of the order of Minimes Fathers. As was frequently done at that period in the case of technical treatises, Father Mersenne wrote his book in Latin, and gave his name the latinized form of Mercennus. He describes Drebbel’s boat, but credits Bourne with having first proposed the principles that Drebbel used, and recalled that Bourne had suggested the possibility of getting fresh air through tubes reaching to the surface. Mercenne’s contribution to the art was his stated belief that the compass would be equally efficient beneath as well as on the surface. [Illustration: DE SON’S UNDERWATER BOAT, 1653 ] In 1653, a French engineer, de Son, constructed in Holland a curious boat, 72 feet long, propelled by a hand-driven wheel. This boat was hardly a submarine as it was not expected to submerge completely. It is interesting as the first application of a mechanical motive force other than oars and the first suggestion of a paddle wheel. It, therefore, marked a great step forward in matters of design. A translation of de Son’s modest description of this boat as shown on the bottom of the design is as follows: ACCURATE REPRESENTATION OF THE NEW WONDERFUL SHIP MADE AT ROTTERDAM. As Mons. Duson has been greatly disappointed at the presentment of his ship, which was in all ways greatly misrepresented, both as regards the rudder, the paddle wheel, and the whole disposition of the vessel when published at Amsterdam, we think it useful to give an exact representation of the ship (as above depicted) and the reader will at once see the difference. The Inventor will undertake to destroy with the ship in one day a fleet of a hundred vessels. No fire, no cannon ball or rocket, no storm or waves can hinder him unless God the Lord should intend to do so. Even if the ships which lie in the harbors consider themselves safe, he will run them to the bottom and turn around just as easily as a bird in the sky so that no one can hurt him, and should his ship be taken by treason, for otherwise it is quite impossible, it could not be governed by any one else but him. He will be able to make in one hour at least ten miles, and should he run on a bank his vessel will swim as light on the water as a light sloop would do. He believes he will be able to go with this vessel in ten weeks to and from the East Indies, and in one day to and from France, so that it may be called the greatest wonder of the world.