been practiced in the use of them, [Illustration: PLATE THE ELEVENTH ] I have now described the leading principles of this mode of warfare; it is well known that all new inventions, and particularly those connected with a government, require years to perfect them, to render them fameliar, effecient; and introduce them into general practice; men must be exersised establishments must be made, and the plan whatever it is Should be pursued with System, But when ever any invention, or project is within the limits of Physics and evidently practicable, it is to be reduced to simple operations and fameliar practice by time; and the inducement to perfect it is always in proportion to the magnitude of the object in View; Every principle her ascerted has already been proved by practice, what then is wanting to make them productive of all the consequences here contemplated? only time and perseverence, even talent is hardly necessary; for all the principal defficulties have been overcome, the question therefore on the policy and true interest of this government concerning these inventions is whether they Should rest in their present state or be left to the proprietors to convert to their own advantage as they think proper; As gun powder, Cannon, muskets, gun locks, and even flints, all had opponents prejudices and established habits to encounter; yet have in time totally Changed the art of war and the relative strength of nations:—So these inventions on submarine navigation and attack may now be considered as the Embryo of a total change in the military marine system; and the existing relative power of States; it, is therefore a subject not only of simple arbitration but one on which the Arbitrators as men of science should deliberate with the utmost care For it is now and by their means, that the present and future Ministers, _the guardiens of the interests of Great Britain_; are to get exact Ideas on this subject, and fully make up their minds, whether there is anything to be hoped or feared from this system; Vulgar men see and admit only of such things as time and practice has rendered fameliar to all Mankind; Men of Sense and science penitrate from principles to future and certain effects. ROBERT FULTON London, August 10th 1806 Additional Notes Of the supply of air in the submarine Vessel * * * * *