John Clerk, of Eldin, Scotland, never went to sea, and yet he devised a scheme of naval tactics, by following which the British Admiral Rodney gained his victory over the French fleet between Dominica and Guadeloupe in April, 1782. Clerk devised his system by the simple plan of thinking intently about naval actions in the large, disregarding such details as guns, rigging, masts, and weather, and concentrating on the movements of the fleets themselves, and the doings of the units of which those fleets were made. He assisted his mental processes by little models of ships, which he carried in his pockets, and which he could, and did, arrange on any convenient table, when he desired to study a problem, or to make a convert. He was enabled by this simple and inexpensive device to see the special problems of fleet tactics more clearly than he could have done by observing battles on board of any ships; for his attention in the ships would have been distracted by the exciting events occurring, by the noise and danger, and by the impossibility of seeing the whole because of the nearness of some of the parts. The amazing result was that he formed a clearer concept of naval tactics than any admiral of his time, finally overcame the natural prejudice of the British navy, and actually induced Rodney to stake on the suggestion of a non-military civilian his own reputation and the issue of a great sea fight. Furthermore, the issue was crowned with success. Nothing could be simpler than Clerk's method. It was, of course, applied to tactics, but similar methods are now applied to strategy; for strategy and tactics, as already pointed out, are based on similar principles, and differ mainly in the fact that strategy is larger, covers more space, occupies more time, and involves a greater number of quantities. Most of the books on naval strategy go into the subject historically, and analyze naval campaigns, and also describe those measures of foresight whereby nations, notably Great Britain, have established bases all over the world and built up great naval establishments. These books lay bare the reasons for the large successes that good naval strategy has attained, both in peace and war, and constitute nearly all there is of the science of naval strategy.