The intervention of the philosophers had not had any appreciable effect. Sir William Petty had indeed projected a great work on the theory of shipbuilding; he had carried out model experiments in tanks, and had invented a double-keeled vessel which, by its performances on passage between Holyhead and Dublin, had drawn public attention to his theories.[21] In his discourse before the Royal Society on Duplicate Proportions, he had opened out new and complex considerations for the shipbuilder; inviting him to forsake his golden rule, or Rule of Three, and apply the law _x varies as y²_ to numerous problems in connection with his craft. But it could soon be shown, by a reference to current practice, that this new law could not be rigidly applied. And the shipbuilder, realizing his own limitations and jealous of sharing his professional mysteries with mathematicians and philosophers, was willing to laugh the new theories out of court. Again, of what practical use had been the discovery of the “solid of least resistance” or of that “cono-cuneus” which Dr. Wallis had investigated with a view to its application to the bows of a ship? A final blow to the scientists was given when the _Royal Katherine_, a three-decker of 80 guns, designed by the council of the Royal Society, was found so deficient in stability that it was deemed necessary to girdle her. Old Shish had beaten Sir Isaac Newton and all the professors! The impossibility of applying abstract scientific principles to so complex a machine as a sailing ship, moving in elements so variable as air and water, was patent to everyone. The attitude of the professional may be judged from the resigned language of William Sutherland, a shipwright of Portsmouth and Deptford Yards, who in 1711 published his _Ship-builder’s Assistant_: “Though some of our preceding Master Builders have proposed length as expedient to increase motion, yet it has seldom answered; much extra timber is required to make them equally strong. Besides, if the solid of least resistance be a blunt-headed solid, extreme length will be useless to make cutting bodies.” Again, in connection with the dimensions of masts: “Though several writers say, that the velocities are the square roots of the power that drives or draws the body; from which it should be a quadruple sail to cause double swiftness. Hence, unless the fashion is adapted to the magnitude of the ship, all our Art can only be allowed notional, and the safest way of building and equipping will be to go to precedent, if there be any to be found. But this is a superfluous caution, since ’tis very customary, that let a ship be fitted never so well by one hand, it will not suit the temper of another. Besides, the proper business of a shipwright is counted an very vulgar imploy, and which a man of very indifferent qualifications may be master of.”