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When once a clear understanding had been obtained there was no difficulty in designing a suitable propeller, with proper diameter, pitch, and area of blade, to meet the requirements of the flier. High efficiency in a screw-propeller is not dependent upon any particular or peculiar shape, and there is no such thing as a "best" screw.
We have then the steam fire-engine; compressed air which he early employed in England, and which has become an instrument of enormous importance in connection with the industrial progress of the age, although this is in no especial degree due to his efforts; the surface condenser, distiller, and evaporator are a permanently and absolutely essential part of modern marine practice; the screw-propeller has almost sole possession of the field of marine propulsion; modern marine engines and boilers in naval practice are always placed below the water-line and are protected by deflective deck armor and frequently by coal as well; the turret has become a permanent and accepted part of the practice of the age, while the monitor type in its essential feature seems to be evanescent.
It must be remembered that the Atlantic was first crossed under steam in 1837, a feat shortly before thought impossible on account of coal consumption, and that the screw-propeller was not generally adopted till several years afterwards.
The question of who invented the screw-propeller in the absolute sense is entirely futile and without answer. No one could ever have reasonably advanced any such unique claim. At the best it is simply a question of the relative influence in the introduction, improvement, and practical application of what was the common property of the engineering practice of the day.
As he spoke, the timbers of the yacht seemed to groan under the pressure; then there was a succession of loud cracks, and the vessel was thrust bodily up the sloping sides of the berg. While in this position, with the bow high and dry, a mass of ice was forced against the stern-post, and the screw-propeller was snapped off as if it had been made of glass.
Then no one knew of the "Monitor;" but twenty-four hours later her name, and that of her inventor Ericsson, were household words in all the States of the Union and the Confederacy. Capt. John Ericsson was a Swedish engineer, residing in this country, who had won a name for himself by inventing the screw-propeller as a means of propulsion for steamships.
A careful and dispassionate study of the facts, so far as they can be known at the present time, seems to indicate clearly that of those who were concerned in successfully adapting the screw-propeller to the needs of marine propulsion and in laying the foundation for these changed conditions, especially in the United States, none was so prominent as Ericsson, or so fairly deserving of the chief credit; and with this judgment the mature thought of the present day seems to agree with little dissent.
Very dimly from time to time a steam siren might be heard upon the river, and once the thudding of a screw-propeller told of the passage of a large vessel along Limehouse Reach. In the eyes of Mrs. Sin Kerry had read menace, and for all their dark beauty they had reminded him of the eyes of a cornered rat.
The screw-propeller was quite a new thing, though the Princeton had carried it, or been carried by it, into the Mediterranean ten years before. Engines designed for its propulsion attracted special attention.
He was, though; and, presently, the sound of the escape steam, that had previously been roaring up through the rattling funnels, ceased; while the fan-blades of the screw-propeller began to revolve, surging up the water of the open dock in which the vessel lay into a mass of foam, and creating, so to speak, a sort of "tempest in a teapot."
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