ed the button; but no one
answered.

Ashton-Kirk looked at his assistant.

"Are you quite sure that our man is there," asked he.

Burgess chewed his straw calmly.

"I'm positive of it," said he.

The fat man now entered at the gate and going to the front door, tried
it. But it was evidently fast, and he turned away. Hesitating for a
moment, he laboriously approached the work shop, the roof of which
could be seen through the trees. Apparently the result was the same
here, for in a very few minutes he was seen to waddle back to his
buggy and climb in with much effort. Then the small horse ambled
forward while the fat man leaned back in great distress.

"You recognize him, do you not?" smiled Ashton-Kirk.

"I do, now," returned Pendleton. "It's our friend Dr. Mercer."

When the buggy arrived at the spot where the motor-car stood, the
doctor regarded its occupants with some surprise.

"Good-morning," greeted Ashton-Kirk.

Painfully, gaspingly the other answered this in kind. The round white
face wore an expression of martyrdom.

"I am pleased to see you once more," said he.

"You like driving in the morning, then?" said the investigator.

The principal's flesh quivered with repulsion.

"It is an exercise ordered by my physician," he answered. "I protested
against it strongly, but he was obdurate. And I am compelled to do it
before I have had my breakfast," hollowly. "It is scarcely short of
barbarous."

Here the small horse stretched its neck and shook itself until the
harness rattled. Pendleton looking from master to beast thought they
might exchange places much to the master's ultimate well-being.

There was a short pause; then Dr. Mercer bent his head toward them.

"When you visited the institute a few nights ago," said he, "you also,
at my request, visited Professor Locke."

Ashton-Kirk nodded.

"For some time," proceeded the other, "I have fancied that there
was something wrong with him. Not of a physical nature, as is,
unfortunately the case with myself, but more in a mental way. But
since that night I have been _sure_ that some sort of a derangement
had fixed itself upon him, or is in progress. He can scarcely be
called the same person. More than once I have been afraid," and here
the speaker lowered his voice to a husky whisper, "that he is
unbalanced."

"That is very grave," said Ashton-Kirk.

"It has occurred to me," went on the doctor, not without shrewdness,
"that something happened t