But more awful was the noise of our own guns. At Nieuport I stood only a few hundred yards away from the warships lying off the coast. Each shell which they sent across the dunes was like one of Jove's thunderbolts, and made one's body and soul quake with the agony of its noise. The vibration was so great that it made my skull ache as though it had been hammered. Long afterwards I found myself trembling with those waves of vibrating sounds. Worse still, because sharper and more piercingly staccato, was my experience close to a battery of French cent-vingt. Each shell was fired with a hard metallic crack, which seemed to knock a hole into my ear-drums. I suffered intolerably from the noise, yet--so easy it is to laugh in the midst of pain---I laughed aloud when a friend of mine, passing the battery in his motor-car, raised his hand to one of the gunners, and said, "Un moment, s'il vous plaît!" It was like asking Jove to stop his thunderbolts. Some people get accustomed to the noise, but others never. Every time a battery fired simultaneously one of the men who were with me, a hard, tough type of mechanic, shrank and ducked his head with an expression of agonized horror. He confessed to me that it "knocked his nerves to pieces." Three such men out of six or seven had to be invalided home in one week. One of them had a crise de nerfs, which nearly killed him. Yet it was not fear which was the matter with them. Intellectually they were brave men and coerced themselves into joining many perilous adventures. It was the intolerable strain upon the nervous system that made wrecks of them. Some men are attacked with a kind of madness in the presence of shells. It is what a French friend of mine called la folie des obus. It is a kind of spiritual exultation which makes them lose self-consciousness and be caught up, as it were, in the delirium of those crashing, screaming things. In the hottest quarter of an hour in Dixmude one of my friends paced about aimlessly with a dreamy look in his eyes. I am sure he had not the slightest idea where he was or what he was doing. I believe he was "outside himself," to use a good old-fashioned phrase. And at Antwerp, when a convoy of British ambulances escaped with their wounded through a storm of shells, one man who had shown a strange hankering for the heart of the inferno, stepped off his car, and said: "I must go back, I must go back! Those shells call to me." He went back and has never been heard of again.