HOW A BIG GUN IS AIMED
The independent line of sight is another modern device for facilitating the service of a gun. With this the gear for giving the gun the elevation necessary to carry a shell to the required distance is kept entirely separate from that used for pointing the gun at the target. The gun-layer has merely to keep his sighting telescope on the target, while another man puts on the range-elevation ordered by the battery commander.
The result of all these improvements is that the best quick-firing guns (among which the French gun is still reckoned) are capable of firing twenty-five rounds a minute. The German field-gun is hardly capable of twenty rounds a minute, being an inferior weapon converted from the old breech-loader.
But these high rates of fire are used only on emergency, as a gun firing twenty-five rounds a minute would exhaust the whole of the ammunition carried with it in the battery in three minutes.
One of the first consequences of the introduction of the shielded gun was the reappearance of the old common shell in an improved form. The common shell is almost as old as Agincourt, and consisted simply of a hollow shell filled with powder, which exploded on striking the object. When shrapnel came into use most nations abandoned the common shell. But shrapnel proved almost ineffective against the shielded gun, and the gunners were indifferent to the bullets pattering on the steel shield in front of them. The answer to this was the high-explosive shell, a steel case filled with high explosive, such as melinite, which is the same as lyddite, shimose, or picric acid. This, when detonated upon striking a gun, can be relied upon to disable it and to kill the gunners behind it.