have hit.

"They are----"

At that moment the telephone bell rang. Malcolm Sage put the receiver
to his ear.

"Yes, Malcolm Sage, speaking," he said. There was a pause. "Yes."
Another pause. "Good, continue to record in that manner;" and once
more he replaced the receiver.

"Vanity, Thompson, is at the root of all error."

"Yes, sir, said Thompson dutifully.

"Those figures," continued Sage, "are times, not numbers."

With a quick indrawing of breath, which with Thompson always indicated
excitement, he reached across for the list, his eyes glinting.

"That was Smart on the telephone, another call just come through,
three-twenty Oxford Street, not three-two-o, but three-twenty. Make a
note of it."

Thompson produced a note-book and hastily scribbled a memorandum.

"At three-twenty this afternoon you will probably find Mr. Montagu
Naylor meeting somebody in Oxford Street. Have both followed. If by
chance they don't turn up, have someone there at three-twenty every
afternoon and morning for a week; it may be the second, third, fourth,
or fifth day after the call for all we know, morning or evening."

"It's the old story, Thompson," said Sage, who never lost a chance of
pointing the moral, "over confidence. Here's a fellow who has worked
out a really original means of communication. Instead of running it
for a few months and then dropping it, he carries on until someone
tumbles to his game."

"Yes, sir," said Thompson respectfully. It was an understood thing at
Department Z. that these little homilies should be listened to with
deference.

"It's like a dog hiding a bone in a hat-box," continued Sage. "He's so
pleased with himself that he imagines no one else can attain to such
mental brilliancy. He makes no allowance for the chapter of accidents."

"That is so, sir."

"We mustn't get like that in Department Z., Thompson."

Thompson shook his head. Time after time Sage had impressed upon the
staff of Department Z. that mentally they must be elastic. "It's only
a fool who is blinded by his own vapour," he had said. He had pointed
out the folly of endeavouring to fit a fact by an hypothesis.

"That's all," and Malcolm Sage became absorbed in the paper before him.
As he closed the door behind him Thompson winked gravely at a print
upon the wall of the corridor opposite. He was wondering how it was
possible for one man to watch the whole of Oxford Street for a week.

CHAPTER IV

GI