"Tompions" are a species of plug used to close the muzzle of a gun when not in action. In the "days of wood and hemp" they were usually painted red, but in modern guns they are generally faced with gun-metal, decorated in some cases with the badge of the ship. "Prime" means to place loose powder in the pan after having pierced the cartridge with a "priming wire" thrust through the touch-hole or vent. To "house" was to haul the gun inboard ready for securing. The smooth-bore gun remained the naval weapon right up to the Crimean War, though explosive shells gradually began to be used as well as the old solid round shot. The rifling of muskets and cannon had often been suggested by inventors as far back as Tudor times, and occasionally a few experimental rifled muskets were made. But in the war with Russia, in which most of the combatants were armed with muzzle-loading rifles, rifled cannon began to make their appearance. The Lancaster gun, with a twisted oval bore, was the first rifled naval gun, and was thought a great deal of in its day. Then came the breech-loading Armstrong guns. These were very finely turned out weapons with poly-groove rifling, and closed at the breech by a species of block which lifted in and out and had somewhat the appearance of a carriage clock. It was held in position by a hollow screw through which the charge and projectile were loaded into the gun, and which was screwed up tight against the breech-block before firing. This was not a very satisfactory system, since, if not properly screwed taut, the block had a habit of blowing out, sometimes with unfortunate results. It was probably for this reason that none of these guns was made bigger than a 100-pounder. The projectiles for the Armstrong gun were covered with leaden jackets in order to take the rifling. This jacket every now and again flew off, which rendered these guns very unsafe to use over the heads of our own troops. [Illustration: NAVAL GUNNERY IN THE OLD DAYS An 18-ton gun in action at the bombardment of Alexandria. The gun has just recoiled after firing. No. 1 is "serving the vent". The sponge end is being passed to be thrust out of the small scuttle in the middle of the port (which is closed as soon as the gun is fired), so that the big wet end can be placed in the gun.]