From the accumulation of trial results thus graphically recorded the designer of new ships can proceed to estimate with greater assurance of attaining satisfactory results than by employing the older methods. If, for example, a ship is to be built of virtually similar dimensions and form to one for which such information is available, but of less speed, the task is simply one of measurement from the curves, with some allowance for probable differences in the constant friction of the engines. If the speed is to be greater than that of the exemplar ship, but still within the limits when wave-making resistance assumes relative importance, the case is also one of simple reading from the curves, with slight corrections. When both the speed and size are different, but the form is approximately the same, the case is more difficult, but it can be dealt with approximately by employing the “law of comparison” or of “corresponding speeds” enunciated by Mr Froude. Formulæ based upon this law—which will be more fully referred to presently—have been devised by one or two designers, and applied by them to problems of the latter class as they occurred in the course of their professional work. Mr John Inglis, junr., described a method of analysis he had adopted, involving the use of Mr Froude’s law, in a paper read before the Institution of Naval Architects in 1877. When unusual speeds are aimed at, or when novel types of vessels have to be dealt with, the only available method of making a trustworthy estimate of the power required lies in the use of direct or deduced results from model experiments. Mr Froude began the work of speed experiments with ships’ models on behalf of the Admiralty at the Experimental Tank in Torquay about 1872, carrying it on uninterruptedly until his death in May, 1879. Since that lamented event the work has been continued with most gratifying results by his son, Mr R. E. Froude. Experiments had, of course, been made by many other investigators previous to Mr Froude, but none before or since have made model experiments so practically useful and reliable. Since the value of the work carried on at Torquay has become appreciated, several experimental establishments of a similar character have been instituted. The Dutch Government, in 1874, formed one at Amsterdam, which, up till his death in 1883, was under the superintendence of Dr Tideman, whose labours in this direction were second only to those of the late Mr Froude. It is now superintended by Mr A. J. H. Beeloo, Chief Constructor, and under him by Mr H. Cop. It was here, it may be remembered, that experiments were made with a model of the Czar of Russia’s yacht _Livadia_, previous to the construction of that extraordinary vessel being begun by Messrs Elder & Co. On the strength of the data so obtained, together with the results of the trials made on Loch Lomond with a miniature of the actual vessel, those responsible for her stipulated speed were satisfied that it