It will thus be seen that model experiments had been made by investigators long before the time of the late Dr. William Froude, of Torquay.  It was not, however, until this gentleman took the subject of resistance of vessels in hand that designers were enabled to render the results from model trials accurately applicable to vessels of full size.  This was principally due to his enunciation and verification by experiment of what is now known as the “law of comparison,” or the law by which one is enabled to refer accurately the resistance of a model to one of larger size, or to that of a full sized vessel.  In effect, the law is this—­for vessels of the same proportional dimensions, or, as designers say, of the same lines, there are speeds appropriate to these vessels, which vary as the square roots of the ratio of their dimensions, and at these appropriate speeds the resistances will vary as the cubes of these dimensions.  The fundament upon which the law is based has recently been shown to have found expression in the works of F. Reech, a distinguished French scientist who wrote early in the century.  There are no valid grounds for supposing that the discovery of Reech was familiar to Froude; but even were this so, it is abundantly evident that, although never claimed by himself, there are the best of grounds for claiming the law of comparison, as now established, to be an independent discovery of Froude’s.

Dr. Froude began his investigations with ships’ models at the experimental tank at Torquay about 1872, carrying it on uninterruptedly until his death in 1879.  Since his decease, the work of investigation has been carried on by his son, Mr. R. E. Froude, who ably assisted his father, and originated much of the existing apparatus.  At the beginning of 1886, the whole experimental appliances and effects were removed from Torquay to Haslar, near Portsmouth, where a large tank and more commodious offices have been constructed, with a view to entering more extensively upon the work of experimental investigation.  The dimensions of the old tank were 280 ft. in length, 36 ft. in width, and 10 ft. in depth.  The new one is about 400 ft. long, 20 ft. wide, and 9 ft. deep.  The new establishment is more commodious and better equipped than the old, and although the experiments are taken over a greater length, the operators are enabled to turn out results with as great dispatch as in the Torquay tank.  The adjacency of the new tank to the dockyard at Portsmouth enables the Admiralty authorities to make fuller and more frequent use of it than formerly.  Since the value of the work carried on for the British government has become appreciated, several experimental establishments of a similar character have been instituted in other countries.  The Dutch government in 1874 formed one at Amsterdam which, up till his death in 1883, was under the superintendence of Dr. Tideman, whose labors in this direction were second only to those of the late Dr. Froude.