The answer is, that with all its acknowledged defects it had merits which universally recommended it, while its successive rivals exhibited defects or disadvantages sufficient to prevent their adoption to its own exclusion. It was a case, in fact, of the survival of the fittest. And if we examine its various features in the light of the records of its performances in action (the truck carriage appears in the background of most of our naval letters and biographies), we shall understand why it was not easily displaced from favour with generation after generation of our officers and seamen. In the first place the truck carriage, a simple structure of resilient elm, with bed, cheek-plates, and trunnions strongly fitted together and secured by iron bolts, was better adapted than any other form for the prevention of excessive stresses, resulting from the shock of recoil, on either gun or ship’s structure. By the expedient of allowing the whole gun equipment to recoil freely across the deck, by allowing the energy of recoil to assume the form of kinetic energy given to the gun and carriage, the violent reactionary stresses due to the sudden combustion of the gunpowder were safely diverted from the ship’s structure, which was thus relieved of nearly the whole of the firing stresses. Moreover, by allowing the gun to recoil readily under the influence of the powder-gases the gun itself was saved from excessive stresses which would otherwise have shattered it. From this point of view the weight of the carriage, relatively to that of the gun, was of considerable importance. If the carriage had been at all too heavy it would not have yielded sufficiently under the blow of the gun, and, howsoever strongly made, would eventually have been destroyed, if it had not by its inertia caused the gun to break; if too light, the violence of the recoil would have torn loose the breechings. Actually, and as the result of a process of trial-and-error continuously carried on, the weight of the finally evolved elm carriage was so nicely adapted to that of its gun that a recoil of the most suitable proportions was generally obtained, a free yet not too boisterous run back. This, of course, upon an even keel. Conditions varied when the guns were at sea upon a moving platform. With the ship heeled under a strong wind the weather guns were often fired with difficulty owing to the violence of the recoil. On the other hand the listing of the ship when attacking an enemy from windward favoured the lee guns by providing a natural ramp up which they smoothly recoiled and down which they ran by gravity to battery, as in a shore emplacement. Of which advantage, as we know, British sea tactics made full use at every opportunity.