winkling
shaft of light coming from among the trees.

"That's the house," said Haines. "I hope the professor ain't busy; you
wouldn't believe what a blowing up he can give a body with his fingers
when he's vexed. I'd almost rather have the doctor himself; though, as
a rule, the professor is a very nice gentleman."

The house was a brick structure of two stories and dimly lighted on
the lower floor. Near by was a long, shed-like building, the windows
of which were brilliantly lighted.

"He's at work," said Haines, in a troubled tone. "And in the shop too!
If it was even the laboratory, it wouldn't be so bad. But he _does_
get so interested in the shop. That machine means more to him,
whatever it is, than anything else about the place."

There came a harsh burring sound from within both the shop and the
house. Haines seemed surprised.

"Visitors," he said. "He seldom has one; and I never knew any to come
at night before."

They saw the figure of Locke cross one of the shed windows toward a
door. And just then Ashton-Kirk stumbled rather heavily against
Haines; the lantern dropped to the ground and was extinguished.

"I beg your pardon," said the investigator in a rueful tone; then he
began to rub his shins. "That was rather hard, whatever it was."

The door of the building opened and Locke appeared; his great bald
head shone in the light that streamed after him; and it was thrust
forward as he strove to penetrate the darkness ahead.

"He feels the vibrations of those buzzers," Haines told them, "and
knows right away when anyone wants to get in."

He began fumbling with the lantern as Locke disappeared; but
Ashton-Kirk said to him:

"You need not light that. We can see very well. And, on second
thought, you need not wait, either. We can introduce ourselves to
Professor Locke without troubling you further."

"Thank you, sir," said the man, vastly relieved. "They all have queer
dispositions, you see, and I don't like to trouble them."

At once Haines made his way back along the path by which they had
approached; some distance away they saw him kindle his lantern, and
then watched the yellow spark as it glanced fitfully away across the
grounds.

The cottage and work-shop of Professor Locke appeared to be set back
some little distance from what Haines had called the county road; a
grove of tall trees thickened the shadows all about, and it was into
these trees that the professor had gone.

"The buzzer must