After the gun had recoiled inboard and had been reloaded, the compressors were slackened and the gun-carriage put on its rollers, so that it ran down the slightly-sloping slide to its firing-position. But for all its simplicity there were very many disadvantages attendant on the muzzle-loader. One very important one was the impossibility of preventing the gases caused by the explosion of the powder from escaping past the projectile, so that part of the force of the explosion was wasted. In breech-loading guns the projectile fits the rifling closely--it could not be forced through the gun by the rammer from the rear--being provided with a copper driving-band of slightly bigger circumference than the bore. When the gun is fired, this is driven into the grooves of the rifling, rotates the shot, and at the same time stops any escape of gas and consequently of energy. Thus, size for size, a breech-loading gun must have greater range and penetration than a muzzle-loader. A breech-loader can be made much longer than a muzzle-loader into the bargain, as it is not necessary to get to the muzzle to load it. This also makes for accuracy and penetration. [Illustration: _Photo. Cribb, Southsea_ 13.5-INCH GUNS ON H.M.S. _CONQUEROR_ The muzzles of the monster cannon are closed by plugs or "tompions" with handsome designs in burnished gun-metal. Above the higher turret is seen a "Barr & Stroud" range-finder in a canvas case.] It was a considerable time before those in this country who had stuck to the muzzle-loading system through thick and thin could be brought to see the error of their ways, but after 1880 breech-loaders much of the French type were introduced into the navy, till we reached the monster 110-ton guns carried in the _Benbow_, _Sanspareil_, and the ill-fated _Victoria_. As I have already mentioned, the French guns were closed at the breech by an "interrupted screw". What this is may be shortly explained. Imagine a screw plug about one and a half times as long as its diameter, with a close thread to it. Now, to screw this in and out of the breech of the gun would be a matter taking an appreciable time. Suppose, now, that we take this screw plug and divide the outside of it--the screw part--perpendicularly into six equal parts. Then, if we cut away the thread of the screw on every other sixth, we shall have three-sixths smooth and the other three-sixths with the screw-thread still standing out upon them. If now we treat the corresponding screw-thread in the breech of the gun itself in a similar manner, and then insert the plug with the three threaded portions in line with the three smooth portions cut in the gun, we can push it directly in to its full length, after which a sixth of a turn will lock the threaded parts together and securely close the breech. This has proved amply strong enough to resist the immense strain imposed by the explosion of the charge; but while the principle has been retained in all our