13378    'They use none. There is a stove.

13379    The bell-rope hangs from the wire just to the right of my desk.

13380    Whoever rang it must have come right up to the desk to do it.

13381    But why should any criminal wish to ring the bell?

13382    It is a most insoluble mystery.'

13383    'Certainly the incident was unusual.

13384    What were your next steps?

13385    You examined the room, I presume, to see if the intruder had left any traces - any cigar-end, or dropped glove, or hairpin, or other trifle?'

13386    'There was nothing of the sort.'

13387    'No smell?'

13388    'Well, we never thought of that.'

13389    'Ah, a scent of tobacco would have been worth a great deal to us in such an investigation.'

13390    'I never smoke myself, so I think I should have observed it if there had been any smell of tobacco.

13391    There was absolutely no clue of any kind.

13392    The only tangible fact was that the commissionaire's wife - Mrs. Tangey was the name - had hurried out of the place.