At the rear end a kind of cap called the breech-piece covers over the ends of all the tubes, itself having a central hole into which fits the breech-block, one of the triumphs of modern engineering, of which more in a moment.
While we have in mind the wire-wound form of construction it is interesting to note that something similar but in a crude form was practised sixty years or more ago. The guns of that era were some of them even of cast iron while the more refined consisted of a steel tube strengthened with coils of wrought iron. This iron was first rolled into flat bars, then it was made hot, and wound on spirally round an iron bar the same size as the tube. A little hammering converted this spiral into a tube which was then fitted round the steel tube. Thus, although very different there is still a distinct resemblance between this old method and the up-to-date wire-wound weapon.
The manufacture of guns, it may be remarked, owes more to one man than to any other, namely, Mons. Gustave Canet, a French engineer who, having fought in the Franco-German War, decided to devote his engineering talents to developing the artillery of his native land. He spent many years in England but later established works at Havre for the manufacture of guns upon improved methods, finally merging his interests into those of the great French armament firm of Schneider of Creusot.
By French and English artillerists at all events the name of Canet is regarded with reverence.
But to get back to our naval gun. It will be clear that operations such as have been described, involving the handling of great tubes fifty feet or more in length, heating them as required, dipping them in oil while hot and so on, can only be carried out at works specially designed for the purpose.
The furnaces where the tubes are heated are well-like formations in the ground, deep enough to take the tube vertically. To lift them in and out there have to be tall travelling cranes capable of catching the tube by its upper end and lifting it right out of the furnace so that its lower end clears the ground. To accomplish this with a little to spare the cranes need to be seventy feet or so high.
Then there are deep pits full of oil so that a tube can be heated in a furnace, drawn out by a crane and quickly dropped into the adjacent oil bath. Likewise there have to be pits of a third kind wherein a cold tube can be set up while a hot one is dropped over it for the purpose of shrinking the latter on.
Then, of course, there have to be lathes of gigantic dimensions capable of taking a length of nearly sixty feet and of swinging an object weighing anything up to fifty tons. But of those machines we can only pause to make mention, for we must pass on to the breech-block, in some ways the most interesting part of the gun.
When it was first suggested to leave the back end of the gun open so that the powder and projectiles could be put in that way instead of through the
muzzle, people at once foresaw how much would depend upon the arrangements for stopping up the hole while the gun was fired. For, of course, the force of the explosion is exerted equally in all directions, backward just as much as forward, so that unless very securely fixed the stopper closing the breech would be liable to become a projectile travelling in the wrong direction. To fix such a thing securely enough to avoid accidents would surely take up too much time and so largely neutralize any advantage arising from its use. These fears were, indeed, to some extent justified by accidents which actually occurred with the early examples of breech-loading guns, and for that reason our own authorities for a time looked askance at breech-loaders.