planets, and their captive satellites, work on the same principle, with
the gravity of the mother planet substituted for the rope, and the
satellite for the rock...."

Sykes stopped the machine, turned, and glared at Roger. "Do you deny
that that is your voice?"

Roger shook his head. "It's my voice all right but--"

"_And_ do you deny that last night, before we left, it was decided that
my explanation would be used?"

Roger's face reddened. "No, sir," he said tightly.

"Then how do you explain that _your_ voice with _your_ explanation is
now on the master spool?" screamed Sykes.

"I--I--can't explain it, sir," said Roger, fighting to control his
temper.

"I can!" snapped Sykes. "You sneaked back in here last night and
substituted your original recording--the one I threw out!"

"But he couldn't have done that, Professor," interjected Tom. "He was
asleep all night!"

"Were you awake all night, Corbett?" asked Sykes coldly.

"No, sir," replied Tom.