action. The tanks of the Somme carried merely machine-guns. Many of those used in the Battle of Liberation were armed with standard-calibre field-guns. Practically, there is no limit to the possible size of tanks. Munitions designers are preparing to build them bigger and bigger, just as naval designers have built warships bigger and bigger—from two hundred-ton caravels which fought the Armada to the 20,000-ton dreadnought. The “land battleship” will doubtless grow in bulk until expense sets a limit. And now, military experts are considering a new possibility of tanks. If a submarine warship may be rendered water-tight, so may a tank be rendered gas-tight.
Poison gas, as I have repeated even to weariness, seems to be the killing weapon of the future. However, the explosive shell is by no means out of date. It merely becomes more or less of an auxiliary to gas. Gas cannot batter down intrenchments and fortifications, destroy buildings, puncture masks or air-proof tanks and fortresses. The explosive shell will still blast the way; the gas will for the most part do the actual job of killing. Explosive-projecting artillery will either be encased in tanks or, when it takes the open, generally mounted on the caterpillar wheel, which gives it far greater mobility, even over rough country, than the swiftest horse-drawn artillery. Designers of tanks and modern gun-carriages are of course studying to increase their speed. We may reasonably expect that even the heavy artil-
