Here we see an innocent agricultural tractor with caterpillar hind wheels. It is out of such a machine that the idea of the formidable tank was evolved.
Thus we get a glimpse of the growth of this simple peaceful agricultural machine into one of the most striking mechanical achievements of the Great War.
Another thing which seems to have grown more or less of itself is the bomb or grenade. Before the time of modern accurate fire-arms hand-grenades were quite a recognized weapon. The "Grenadier" Guards owe their title to this fact and carry the design of a bursting grenade upon their uniforms. Yet until a few years ago everyone thought that such things were done with for ever: that with modern rifles soldiers would seldom get near enough together to use grenades and that if they did the bayonet would be the weapon to be used.
When, however, the Germans were driven back at the battle of the Marne and found themselves compelled to entrench in order to avoid further disaster, it soon became evident that neither rifle nor bayonet nor both together entirely filled the needs of the infantryman.
Since the Allies were not powerful enough to drive the Germans from their trenches forthwith, they, too, had to entrench. Gradually the trenches drew nearer and nearer together and at the same time skill in entrenching increased. Thus a time soon arrived when both rifle and bayonet were largely useless for purposes of offence. Then the hand-grenade came into its own again, for the men could throw it from the depths of their own trench high into the air in the hope that it would fall into the
trenches of the enemy. The call for these quickly produced the supply. There is little need to describe them here, for who among us has not intimate friends who used them again and again? This much may be said, however. They were little hollow balls of cast iron, sometimes chequered so that when they burst they flew into many fragments. Inside was a charge of explosive with a suitable fuse or firing mechanism. Some were fixed to the end of a stick for convenience in throwing, while others were simply handled like a cricket-ball.
They serve to show us, however, how an old idea may under fresh conditions be revived into what is practically a new invention.
Another example of the same sort is the revival of chain mail. Who, but a few years ago, would have thought it possible that modern soldiers would go to battle sheathed in shirts consisting of little metal plates cunningly connected by wire links and so overlapping each other as to form a perfect shield for all the more vital parts of the body? To what extent these were worn I do not know, for the British soldier is a very shy fellow in some ways and there are few who would not be a trifle ashamed to let their comrades see them thus garbed. They would feel that it was a confession of fear, and however afraid an Englishman may be he will never admit it. He is really a pious fraud, for the more he is really afraid inwardly the more courageously will he act just to hide his fear.
Since, however, the bullet-proof helmet is worn officially nowadays there seems no reason whatever
why the bullet-proof waistcoat should not be adopted officially too. It is very light and very flexible and it is claimed that it is quite effectual in stopping rifle and machine-gun bullets.