Now at the time we could not understand these things, but later I was to learn the meaning of these ominous kopjes that gathered in the twilight. Each of the Martians, standing in the great crescent I have described, had discharged, by means of the gunlike tube he carried, a huge canister over whatever hill, copse, cluster of houses, or other possible cover for guns, chanced to be in front of him. Some fired only one of these, some two--as in the case of the one we had seen; the one at Ripley is said to have discharged no fewer than five at that time. These canisters smashed on striking the ground--they did not explode--and incontinently disengaged an enormous volume of heavy, inky vapour, coiling and pouring upward in a huge and ebony cumulus cloud, a gaseous hill that sank and spread itself slowly over the surrounding country. And the touch of that vapour, the inhaling of its pungent wisps, was death to all that breathes.

It was heavy, this vapour, heavier than the densest smoke, so that, after the first tumultuous uprush and outflow of its impact, it sank down through the air and poured over the ground in a manner rather liquid than gaseous, abandoning the hills, and streaming into the valleys and ditches and watercourses even as I have heard the carbonic-acid gas that pours from volcanic clefts is wont to do. And where it came upon water some chemical action occurred, and the surface would be instantly covered with a powdery scum that sank slowly and made way for more. The scum was absolutely insoluble, and it is a strange thing, seeing the instant effect of the gas, that one could drink without hurt the water from which it had been strained. The vapour did not diffuse as a true gas would do. It hung together in banks, flowing sluggishly down the slope of the land and driving reluctantly before the wind, and very slowly it combined with the mist and moisture of the air, and sank to the earth in the form of dust. Save that an unknown element giving a group of four lines in the blue of the spectrum is concerned, we are still entirely ignorant of the nature of this substance.

Once the tumultuous upheaval of its dispersion was over, the black smoke clung so closely to the ground, even before its precipitation, that fifty feet up in the air, on the roofs and upper stories of high houses and on great trees, there was a chance of escaping its poison altogether, as was proved even that night at Street Cobham and Ditton.

The man who escaped at the former place tells a wonderful story of the strangeness of its coiling flow, and how he looked down from the church spire and saw the houses of the village rising like ghosts out of its inky nothingness. For a day and a half he remained there, weary, starving and sun-scorched, the earth under the blue sky and against the prospect of the distant hills a velvet-black expanse, with red roofs, green trees, and, later, black-veiled shrubs and gates, barns, outhouses, and walls, rising here and there into the sunlight.

But that was at Street Cobham, where the black vapour was allowed to remain until it sank of its own accord into the ground. As a rule the Martians, when it had served its purpose, cleared the air of it again by wading into it and directing a jet of steam upon it.