"that recovers the dose you got a couple of weeks ago while
Willis watched me. I don't think you really need any menthium; your
brain is too active to suit me as it is."

He gave an evil chuckle and walked to the far side of the cave and
opened a secret panel. He drew from a recess a flask and carefully
emptied a portion of the contents of the syringe into it. He replaced
the flask and closed the panel, and with another chuckle he limped
over to a chair and threw himself down in it. For an hour he sat
motionless and Dr. Bird carefully worked his way back along the branch
and climbed the rope and started for the hollow.

* * * * *

A faint whirring noise attracted his attention, and he could see the
faintly luminous globe in the distance, rapidly approaching. It came
to a stop at the spot where it had previously landed and four men got
out. Instead of going toward the cave, they towed the globe, which
floated a few inches from the earth, toward the side of the hill
farthest from where the doctor stood. Three of them held it, while the
fourth went forward and bent over some controls on the ground. A
creaking sound came through the night and the men moved forward with
the globe. Presently its movement stopped and men reappeared. Again
came the creaking sound and the glow faded out as though a screen had
been drawn in front of it. The four men walked toward the door of the
cave.

Dr. Bird dropped flat on the ground and saw them pause a few yards
below him on the hill and again work some hidden controls. A glare of
light showed for an instant and they disappeared and everything was
again quiet. Dr. Bird debated the advisability of returning to the
window but decided against it and moved down the face of the hill.

Inch by inch he went over the ground, but found nothing. In the
darkness he could not locate the door and he made his way around to
the back of the hill. The precipice loomed above him and he swept it
with his gaze, but he could locate no opening in the darkness and he
dared not use a flash-light. As he turned he faced the east and noted
with a start of surprise that the sky was getting red. He glanced at
his watch and found that Carnes had been gone for nearly three hours.

"Great Scott!" he exclaimed in surprise. "Time has gone faster than I
realized. He ought to be back at any time now."

* * * * *

He mounted the highest point of the hill a