The third of the “newfangled ideas” is really a very old idea, as the reader will observe. It is a submarine boat designed to travel in ordinary circumstances with its back out of water, and yet be able, when occasion requires, to go underneath altogether. It is the invention of Mr. John P. Holland, who for many years has been at work on the cigar-shaped diving-ship idea. The one now building (1897) is only eighty-five feet long by eleven in diameter--a mere model of what a ship ought to be, if the idea were to be thoroughly tested. It might, indeed, be of some use for raising a blockade of the port of New York, just as smaller vessels were used to damage Union ships off Charleston in the Civil War. But, as already said over and again, the navy that the American nation needs is one that will prevent any nation on earth contemplating a blockade of any American port. However, this is not to condemn the building of this submarine boat. It was well worth building, just as the tiny ship in which Ericsson proved his screw propeller was worth building. Considerable space was given in Volume I to the doings of the submarine boats in the Revolutionary War because the building of ships which might be entirely submerged has never been attempted on a scale that would warrant a fair trial of the idea. There are many difficulties to be overcome, the chief of which is due to the fact that the ordinary compass goes wrong altogether when placed in a diver. It is nevertheless reasonable to suppose that every defect may be overcome. It is certain that the defects will not be overcome until a fair trial of the ship is had. Because of certain manifest advantages in having a ship that can live entirely submerged as well as when awash, or floating high out of water, there are men who believe that such ships will eventually become veritable peace-makers. We who are conservatives call them visionaries, and they reply that men of our class called Capt. M. C. Perry a visionary in 1839 because he said he believed that steamships would eventually supersede the gloriously beautiful frigate of the olden day. [Illustration: Another One of the Holland Submarine Boats: the _Plunger_. (Submerged, with camera lucida tube in position.) _From a photograph of a drawing belonging to the John P. Holland Co._]