accomplice's hair. The four pounds a week was a lure which must draw him,
and what was it to them, who were playing for thousands? They put in the
advertisement, one rogue has the temporary office, the other rogue incites
the man to apply for it, and together they manage to secure his absence
every morning in the week. From the time that I heard of the assistant
having come for half wages, it was obvious to me that he had some strong
motive for securing the situation."

"But how could you guess what the motive was?"

"Had there been women in the house, I should have suspected a mere vulgar
intrigue. That, however, was out of the question. The man's business was a
small one, and there was nothing in his house which could account for such
elaborate preparations, and such an expenditure as they were at. It must
then be something out of the house. What could it be? I thought of the
assistant's fondness for photography, and his trick of vanishing into the
cellar. The cellar! There was the end of this tangled clew. Then I made
inquiries as to this mysterious assistant, and found that I had to deal
with one of the coolest and most daring criminals in London. He was doing
something in the cellar--something which took many hours a day for months
on end. What could it be, once more? I could think of nothing save that he
was running a tunnel to some other building.

"So far I had got when we went to visit the scene of action. I surprised
you by beating upon the pavement with my stick. I was ascertaining whether
the cellar stretched out in front or behind. It was not in front. Then I
rang the bell, and, as I hoped, the assistant answered it. We have had
some skirmishes, but we had never set eyes upon each other before. I
hardly looked at his face. His knees were what I wished to see. You must
yourself have remarked how worn, wrinkled, and stained they were. They