Through kilometre after kilometre of gaslit clattering monotony that immense and deafening conveyance took me.  There were cafes everywhere, thickly strewn on both sides of the way—­at first large and lofty and richly decorated, with vast glazed facades, and manned by waiters in black and white, then gradually growing smaller and less busy.  The black and white waiters gave place to men in blouses, and men in blouses gave place to women and girls—­short, fat women and girls who gossiped among themselves and to customers.  Once we passed a cafe quite deserted save for the waiter and the waitress, who sat, head on arms, side by side, over a table asleep.

Then the tram stopped finally, having covered about three miles.  There was no sign of a cab.  I proceeded on foot.  The shops got smaller and dingier; they were filled, apparently, by the families of the proprietors.  At length I crossed over a canal—­the dreadful quarter of La Villette—­and here the street widened out to an immense width, and it was silent and forlorn under the gas-lamps.  I hurried under railway bridges, and I saw in the distance great shunting-yards looking grim in their blue hazes of electric light.  Then came the city barrier and the octroi, and still the street stretched in front of me, darker now, more mischievous, more obscure.  I was in Pantin.

At last I descried the white and blue sign of the Rue Thiers.  I stood alone in the shadow of high, forbidding houses.  All seemed strange and fearsome.  Certainly this might still be called Paris, but it was not the Paris known to Englishmen; it was the Paris of Zola, and Zola in a Balzacian mood.

I turned into the Rue Thiers, and at once the high, forbidding houses ceased, and small detached villas—­such as are to be found in thousands round the shabby skirts of Paris—­took their place.  The Villa des Hortensias, clearly labelled, was nearly at the far end of the funereal street.  It was rather larger than its fellows, and comprised three stories, with a small garden in front and a vast grille with a big bell, such as Parisians love when they have passed the confines of the city, and have dispensed with the security of a concierge.  The grille was ajar.  I entered the garden, having made sure that the bell would not sound.  The facade of the house showed no light whatever.  A double stone stairway of four steps led to the front door.  I went up the steps, and was about to knock, when the idea flashed across my mind:  “Suppose that Deschamps is really dying, how am I to explain my presence here?  I am not the guardian of Rosa, and she may resent being tracked across Paris by a young man with no claim to watch her actions.”

Nevertheless, in an expedition of this nature one must accept risks, and therefore I knocked gently.  There was no reply to the summons, and I was cogitating upon my next move when, happening to press against the door with my hand, I discovered that it was not latched.  Without weighing consequences, I quietly opened it, and with infinite caution stepped into the hall, and pushed the door to.  I did not latch it, lest I might need to make a sudden exit—­unfamiliar knobs and springs are apt to be troublesome when one is in a hurry.