But one or two of the younger and brighter minds in the profession, more especially those who had the advantage of Rankine's direct tuition, felt that the old beliefs as to resistance presented such anomalous and unreconcilable results that they could not be founded on any true law of nature. John Inglis, jun., then a mere boy, instituted in Pointhouse Shipyard Rankine's method of estimating the resistance of ships, and for many years was alone in this mode of investigation. [Illustration: Resistance curves Model of S.S. 'Merkara.' SPEED IN FEET PER MINUTE RESISTANCE IN LBS.] But with Froude's experiments all doubt on the matter vanished. It was no longer a question of 'condemned mathematics.' Froude had the happy knack of writing so that the proverbial schoolboy could understand him; and the schoolboy could see the value of resistance to motion through water weighed out as simply and accurately as a pound of currant bun. These experiments for the determination of the frictional resistance of water, published in 1874, were supplemented presently by experiments on models of actual ships, and also by towing a full-size ship, the 'Greyhound,' her resistance at various speeds being recorded by means of a dynamometer on board the 'Active,' the vessel towing her. The results of the experiments on model and ship were set out in a curve, when it was found, after the necessary corrections were made, that both curves were of precisely similar character. A basis of comparison between model and ship was thus established, the measure of this being set forth in what is known as Froude's law of comparison, which may thus be stated. The equivalent speed of a ship and the model it represents will vary as the square root of their lengths. Thus, in the case of a ship 100 feet long represented by a model 4 feet long, the equivalent speed of the ship would be five times that of the model, and at these equivalent speeds would present similar phenomena connected with resistance as the model does. This fact enormously increased the knowledge of investigators, and it was belief in it that gave the writer absolute confidence in carrying out the design of the 'Vanduara,' though he possessed experience in small boats only. Mr. Froude also split up the several elements of resistance to motion through the water into their component parts, assigning a value to each, and showing what was due to surface friction and eddy-making, and what to wave-making. Scott Russell had already argued for a given length of fore and after body for any given speed, and this was recognised by yacht-builders to some extent by their gradually lengthening out their vessels; but the disadvantages as well as the advantages of length could only be thoroughly realised on investigating Froude's experiments. An example is given of such an experiment in the diagram, which shows the resistance curve of a model of the 'Merkara,' built by Messrs. Denny Bros., at Dumbarton, where