So saying, he threw a light, shabby-looking carpet-bag up to the driver, who deposited it by his side, and drove off.

After sleeping for a few hours at a hotel where he was well-known, and having urgent business in the city next morning, the doctor deposited his luggage, which he had left with sundry rugs and shawls in charge of the hotel night porter, at his own door on his way to keep his business appointment, leaving word that he should be at home in the afternoon. With the other luggage there was handed in the shabby-looking carpet-bag which had come with it.

“What’s this?” asked the boy-in-buttons, in a tone of disgust, of the housemaid, as he touched the bag with his outstretched foot.

“I don’t know, I’m sure,” was the reply. “It ain’t anything as master took with him, and I’m quite sure it don’t belong to mistress.”

“I’ll tell you what it is,” said the boy abruptly, and in a solemn voice, “it’s something as has to do with science. There’s something soft inside it, I can feel. P’raps there’s something alive in it—I shouldn’t wonder. Oh! P’raps there’s gun-cotton in it. I’d take care how I carried it if I was you, Mary, or p’raps it’ll go off and blow you to bits!”

“Oh goodness!” exclaimed the housemaid, “I won’t touch it. Just you take it yourself and put it into master’s study; it’ll be safest there.”

So the boy, with a grin of extreme satisfaction at the success of his assault on the housemaid’s nerves, helped her to carry the rest of the luggage upstairs, and then deposited the mysterious bag in a corner of the doctor’s own special sanctum. Now this study was a room worth describing, and yet not very easy to describe.

The doctor’s house itself was one of those not very attractive-looking dwellings which are to be found by streetfuls running from square to square in the west end of London. It had stood patiently there for many a long year, as was evident from the antiquated moulding over the doorway, and from a great iron extinguisher, in which the link-bearers of old used to quench their torches, which formed part of the sombre-coloured ironwork that skirted the area. The gloomy monotony of the street was slightly relieved by a baker’s shop at one corner and a chemist’s at the other. But for these, the general aspect would have been one of unbroken dinginess.

Nor did the interior of the doctor’s house present a much livelier appearance.

The entrance-hall, which was dark and narrow, had rather a sepulchral smell about it, which was not otherwise than in keeping with some shelves of books at the farther end—the overflow apparently of the doctor’s library; the tall, dark volumes therein looking like so many tombs of the dead languages.