k later. The
professor's last words were significant: 'Anyway, Chambers, you will
be the first to know.' If the experiments had proved fatal, how
could Sir Jasper be the first to know unless an appointment had been
made for him to call at the laboratory and discover for himself the
result?"

The inspector coughed noisily.

"When Sir Jasper learned of the unqualified success of the
experiments, and saw by the professor's changed appearance proof of
his triumph, he remembered the article in _The Present Century_. He
realised that in the lengthening of human life a terrible
catastrophe threatened the world. Humanitarianism triumphed over his
affection for his friend, and he killed him."

Sir John Dene nodded his head in agreement. The inspector was
leaning forward, his arms on the table, staring at Malcolm Sage with
glassy eyes.

"The assailant was clearly a tall, powerful man and left-handed.
That was shown by the nature of the blow. That he had some knowledge
of physiology is obvious from the fact that he made no attempt at a
second blow to insure death, as a layman most likely would have done.
He knew that he had smashed the occipital bone right into the brain.
In his early years Sir Jasper studied medicine.

"The crime committed, Sir Jasper proceeded to cover his tracks. With
the poker he loosened the sockets of the bolts and that of the lock
in order to give an impression that the door had been burst open
from without. He then left the place and, to suggest robbery as a
motive for the crime, he took with him the professor's gold watch,
which he threw away. This was found a few hours later by the tramp
whom you, Carfon, want to hang for a crime of which he knows
nothing." There was a note of sternness in Malcolm Sage's voice.

"But----" began the inspector.

"I suspect," continued Malcolm Sage, "that after he had left the
laboratory, Sir Jasper suddenly realised that the professor had
probably recorded in his book all his processes. He returned,
discovered the manuscript, and was for hours absorbed in it, at
first smoking continuously, later too interested in his task to
think of his pipe. It must be remembered that he had studied
medicine."

The inspector glanced across at Sir John Dene, who sat rigidly in
his chair, his eyes fixed upon Malcolm Sage.

"I rather think that he was aroused from his preoccupation by the
ringing of the bell announcing the arrival of the professor's
breakfast. He then realised