Standing on the pavement, Colin inspected what was probably his future residence with a considerable amount of curiosity. He was not in the least fanciful, but even to a thoroughly healthy imagination the old house certainly presented a forlorn and rather mysterious aspect. There seemed to him nothing surprising in the fact that, having once been burgled, the Professor had begun to feel the need of a trustworthy assistant, especially if he were engaged in researches which would undoubtedly possess a large financial value. On the right of the gate a rusty bell-handle lolled out dejectedly from its socket. Colin gave it a vigorous pull, and a distant jingling somewhere inside the house told him that the wire was still in working order. Looking through the grille, he waited patiently for the best part of a minute. At last he heard the sound of somebody fumbling with a chain, then the front door opened, and an old, bent woman came slowly down the steps. Holding her shawl together with one hand, she shuffled along to the end of the passage and peered at him through the ironwork. "Are you the gentleman that's expected?" she asked suspiciously. "It's quite likely," said Colin. "Anyhow, I had a telegram from Professor Carter asking me to call at three-thirty." "That must be right, then," was the somewhat grudging answer, and, turning the lock, she pulled back the gate just wide enough for him to enter. Following her up the passageway and through the front door, Colin found himself in a big, well-lighted hall, at the back of which a couple of French windows opened out into the garden behind. Several pieces of massive Victorian furniture were ranged symmetrically round the walls, and a broad, thickly carpeted staircase led up to the landing above. "If you'll step into the library," observed his guide, "I'll tell Mr. Carter you've come." She opened a door on the right, and, accepting her invitation, Colin passed through into a long, cheerless apartment, three sides of which were almost completely lined with books. There was no fire in the grate, and such chairs as there were looked so extremely uncomfortable that only the most hardened man of letters could have described it as an agreeable resort. Colin did not attempt to sit down. After a cursory glance round he walked over to the nearest bookcase and began to examine the titles of some of the volumes, all of which appeared to deal with scientific subjects, a fair proportion of them being in French and German. He was deep in this occupation when he heard the door open, and, wheeling round quickly, he found the Professor coming toward him.