They slowly crossed the basement floor. The air-holes placed at intervals admitted a pale light; while in the dark corners, and along the narrow corridors, gas was constantly burning. In these corridors were the reserves, large vaults closed with iron railings, containing the surplus goods of each department. As he passed along Mouret glanced at the heating apparatus which was to be lighted on the following Monday for the first time, and at the firemen guarding a giant gas-meter enclosed in an iron cage. The kitchen and dining-rooms, old cellars turned into habitable apartments, were on the left near the corner of the Place Gaillon. At last, right at the other end of the basement, he arrived at the delivery office. Here, all the purchases which customers did not take away with them, were sent down, sorted on tables, and placed in compartments each of which represented a particular district of Paris; then by a large staircase opening just opposite The Old Elbeuf, they were sent up to the vans standing alongside the pavement. In the mechanical working of The Ladies' Paradise, this staircase in the Rue de la Michodière was ever disgorging the goods devoured by the slide in the Rue Neuve-Saint-Augustin, after they had passed through the mill of the counters up above. "Campion," said Mouret to the delivery manager, a retired sergeant with a thin face, "why weren't six pairs of sheets, bought by a lady yesterday about two o'clock, delivered in the evening?" "Where does the lady live?" asked the employee. "In the Rue de Rivoli, at the corner of the Rue d'Alger--Madame Desforges." At this early hour the sorting tables were yet bare and the compartments only contained a few parcels left over night. Whilst Campion was searching amongst these packets, after consulting a list, Bourdoncle looked at Mouret, reflecting that this wonderful fellow knew everything, thought of everything, even when he was supposed to be amusing himself. At last Campion discovered the error; the cashiers' department had given a wrong number, and the parcel had come back. "What is the number of the pay-desk that debited the order?" asked Mouret: "No. 10, you say?" And turning towards his lieutenant, he added: "No. 10; that's Albert, isn't it? We'll just say two words to him."