The last daylight—­how often our lightest words are omens!—­faded out of the sky.  Emily kept her eyes upon the windows none the less.  She tried to understand what her father was saying sufficiently to put in a word now and then, but her sense of hearing was strained to its utmost for other sounds.  There was no traffic in the road below, and the house itself was hushed; the ticking of the old clock, performed with such painful effort that it ever seemed on the point of failing, was the only sign of life outside the garret.  At length Emily’s ear caught a remote rushing sound; her father’s low voice did not overcome it.

‘These compounds of nitrogen and oxygen,’ he was saying, ’are very interesting.  Nitrous oxide, you know, is what they call Laughing Gas.  You heat solid nitrate of ammonia, and that makes protoxide of nitrogen and water.’

The words conveyed no sense to her, though she heard them.  The rushing sound had become a dull continuous thunder.  Her eyes strained into the darkness.  Of a sudden the horizon flamed.  A train was passing a quarter of a mile away, and the furnace-door of the engine had just been opened to feed the fire, whose strength sped the carriages to far-off London.  A streaming cloud of smoke reflected the glare; it was as though some flying dragon vomited crimson fumes.  Involuntarily the girl half rose from her seat and pointed.

‘What is it?’ asked her father, looking round.  ’Ah! pretty sight that fire on the smoke.  Well, this protoxide of nitrogen, you see—­’

CHAPTER VII

ON THE LEVELS

Not the least of many mysteries in the natural history of the Cartwrights was, how they all managed to bestow themselves in the house which they occupied.  To be sure, the family—­omitting Mr. Cartwright, seldom at home—­were all of one sex, which perhaps made the difficulty less insuperable; but the fact remained that Mrs. Cartwright and her five grown-up daughters, together with a maid-servant, lived, moved, and had their being in an abode consisting of six rooms, a cellar, and a lumber closet.  A few years ago they had occupied a much more roomy dwelling on the edge of the aristocratic region of Dunfield; though not strictly in St. Luke’s—­the Belgravia of the town—­they of course spoke of it as if it were.  A crisis in the fortunes of the family had necessitated a reduction of their establishment; the district in which they now dwelt was humbler, but then it could always be described as ‘near North Parade, you know’; North Parade being an equivalent of Mayfair.  The uppermost windows commanded a view of the extensive cattle-market, of a long railway viaduct, and of hilly fields beyond.