“The faucet leaked. The cup was very nearly full.
“The dropping water filled this little bottle in one minute and ten seconds. The bottle holds the hundredth part of a pint. The cup holds half a pint. Therefore, the leaking water would fill it in fifty-eight seconds. So somebody set that cup under the faucet less than an hour before I arrived.”
“Upon my word, Nick,” said the chief, “you can make a clock out of anything.”
“Dropping water is a first-rate timepiece,” Nick replied. “That’s why I had this bottle made.”
“Except the joiner work, was there anything in the rooms to show that Helstone had occupied them?”
“No, but it’s pretty well known in the district now. That’s the peculiar thing about Helstone. He always knows just when to flit.
“Before he goes, nobody knows anything about him. Ten minutes later, everybody knows.”
“But nobody has ever seen Helstone himself.”
“No; the inspector has got descriptions of some of his men, but there is no description of Helstone. He’s really only a rumor, a mysterious influence guiding the movements of those ruffians.”
“Well,” said the chief, after a pause, “what did you do next?”