was tickling provokingly, I began to cough and my windpipe felt too small. I hastened forward, but, even as I went, the light grew dimmer and the swirling fog more dense. I groped blindly, began to run, stumbled, and in that moment my hand came in contact with an unseen rope. On I went into gloom, into blackness, until I was presently aware of my companions in front and mightily glad of it. In a while, still following this invisible rope, we turned a corner, the fog grew less opaque, thinned away to a green mist, and we were out in the daylight again, and thankful was I to whip off my stifling helmet and feel the clean wind in my hair and the beat of rain upon my face.
"Notice the ticklin' feelin'?" enquired our sub., as he took our helmets and put them carefully by. "Bit tryin' at first, but you soon get used to it — yes, rather. Some of the men funk tryin' at first — and some hold their breath until they fairly well burst, an' some won't go in at all, so we carry 'em in. That gas you've tried is