Then, without warning or signal, it slipped off, as though casually, towards an undetermined goal.

Often it ran level with the roofs of vague, far-stretching acres of houses-- houses vile and frowsy, and smoking like pyres in the dank air.

And always it travelled on a platform of brick arches.

Now and then the walled road received a tributary that rounded subtly into it, and this tributary could be seen curving away, on innumerable brick arches, through the chimneypots, and losing itself in a dim horizon of gloom.

At intervals a large, lifeless station brought the train to a halt for a moment, and the march was resumed.