When, over twenty years ago, Admiral J. A. G. Troup wrote his admirable book On the Bridge, he said that he had searched his soul to find a reason for burdening even one of his brethren with his observations on handling ships. That his diffidence was quite unfounded is, of course, proved by the fact that his book, at any rate in naval circles, has become a near classic. The fact is that there is remarkably little real opportunity for junior officers at sea to gain experience in the actual manœuvring of ships in restricted waters, and aspiring shipmasters will seize with avidity any crumbs of knowledge which may fall from the table of the experienced. And, while it is clearly true that much practical experience is essential, that experience will be dearly bought and largely wasted if the underlying principles are not clearly understood, and unless the practitioner learns what he must look for, and what will affect the issue. How often has one made, or heard others make, some such remark as ‘and then the wind caught her bows and I couldn't do a damn' thing about it’. But on reflection one realized that the observation should have been qualified by the admission that one had got into what, in sailing parlance, is known as ‘the hopeless position’, and should never have been there at all if a proper appreciation of the problem had been made.