For the remarkable thing that overtook Rooum—­(that, by the way, is an odd way to put it, as you’ll see presently; but the words came that way into my head, so let them stand)—­for the remarkable thing that overtook Rooum, I don’t think I can begin better than with the first time, or very soon after the first time, that I noticed this peculiarity about the echoes.

It was early on a particularly dismal November evening, and this time we were somewhere out south-east London way, just beyond what they are pleased to call the building-line—­you know these districts of wretched trees and grimy fields and market-gardens that are about the same to real country that a slum is to a town.  It rained that night; rain was the most appropriate weather for the brickfields and sewage-farms and yards of old carts and railway-sleepers we were passing.  The rain shone on the black hand-bag that Rooum always carried; and I sucked at the dottle of a pipe that it was too much trouble to fill and light again.  We were walking in the direction of Lewisham (I think it would be), and were still a little way from that eruption of red-brick houses that ... but you’ve doubtless seen them.

You know how, when they’re laying out new roads, they lay down the narrow strip of kerb first, with neither setts on the one hand nor flagstones on the other?  We had come upon one of these. (I had noticed how, as we had come a few minutes before under a tall hollow-ringing railway arch, Rooum had all at once stopped talking—­it was the echo, of course, that bothered him.) The unmade road to which we had come had headless lamp-standards at intervals, and ramparts of grey road-metal ready for use; and save for the strip of kerb, it was a broth of mud and stiff clay.  A red light or two showed where the road-barriers were—­they were laying the mains; a green railway light showed on an embankment; and the Lewisham lamps made a rusty glare through the rain.  Rooum went first, walking along the narrow strip of kerb.

The lamp-standards were a little difficult to see, and when I heard Rooum stop suddenly and draw in his breath sharply, I thought he had walked into one of them.

“Hurt yourself?” I said.

He walked on without replying; but half a dozen yards farther on he stopped again.  He was listening again.  He waited for me to come up.

“I say,” he said, in an odd sort of voice, “go a yard or two ahead, will you?”

“What’s the matter?” I asked, as I passed ahead.  He didn’t answer.

Well, I hadn’t been leading for more than a minute before he wanted to change again.  He was breathing very quick and short.

“Why, what ails you?” I demanded, stopping.

“It’s all right....  You’re not playing any tricks, are you?...”

I saw him pass his hand over his brow.

“Come, get on,” I said shortly; and we didn’t speak again till we struck the pavement with the lighted lamps.  Then I happened to glance at him.