"You have the records, Whiting" he asked.

"Yes, Professor."

"I may say," said Kennedy, "that each of your chairs is wired
under the arm in such a way as to betray on an appropriate
indicator in the next room every sudden and undue emotion. Though
it may be concealed from the eye, even of one like me who stands
facing you, such emotion is nevertheless expressed by physical
pressure on the arms of the chair. It is a test that is used
frequently with students to demonstrate various points of
psychology. You needn't raise your arms from the chairs, ladies
and gentlemen. The tests are all over now. What did they show,
Whiting?"

The student read what he had been noting in the next room. At the
production of the coat during the demonstration of the markings
of the bullet, Mrs. Parker had betrayed great emotion, Mr. Bruce
had done likewise, and nothing more than ordinary emotion had
been noted for the rest of us. Miss La Neige's automatic record
during the tracing out of the sending of the note to Parker had
been especially unfavourable to her; Mr. Bruce showed almost as
much excitement; Mrs. Parker very little and Downey very little.
It was all set forth in curves drawn by self-recording pens on
regular ruled paper. The student had merely noted what took place
in the lecture-room as corresponding to these curves.

"At the mention of the noiseless gun," said Kennedy, bending over
the record, while the student pointed it out to him and we leaned