For years and centuries man has longed to be able to navigate the air, and to this end he has tried all shapes and kinds of balloons, yet he is always more or less dependent on the currents of the sky. But the recent jump from years of failure to marvellous success is due as much to the collateral invention and development of the motor. It was chance that caused the aeroplane and the motor industry to develop simultaneously, and yet but for the latter the former could not have advanced. It is much the same with the evolution of the steamship. It was only after Solomon de Caus had, early in the seventeenth century, published his treatise on the application of steam as a means for elevating water, and the Marquis of Worcester, in 1663, had published his description of “An admirable and most forcible way to drive up water by fire,” that Papin was able to supply the key to the question of the mechanical propulsion of ships. Even if it were possible to prove that he had never acquainted himself with the theories of de Caus and the Marquis of Worcester, that argument would avail but little, for the solution was bound to come sooner or later; it was inevitable. There must be, man reasoned, some means for propelling a ship along the water other than by sails or oars. The Chinese had been working at the idea, the Romans had at least attempted it; through the Middle Ages there had been actually accredited instances, and so the eighteenth century was not too soon for its accomplishment. Thus, when Papin determined to apply steam power to vessels, he was just one of those many benefactors of the world who have succeeded by means of Nature to overcome Nature: by employing fire and water to overcome water and space.