The Film Mystery
24. The Invisible Menace
Mackay and I exchanged glances. Kennedy busied himself putting away some of the
more important bits of evidence in the case, placing the tiny tubes of solution, the blood
smears, and other items together in a cabinet at the farther corner of the laboratory. The
vast bulk of his paraphernalia, the array of glass and chemicals and instruments, he left
on the table for the morning. Then he faced us again, with a smile.
"Suppose you start up the percolator once more, Walter!" He took a cigar and lighted it
from the match I struck. "I believe I've earned another cup of coffee," he added.
Mackay had been fidgeting considerably since Kennedy's explanation of the possible
danger to Shirley, as well as to ourselves or even to others.
"Isn't there something we can do, Kennedy?" he exclaimed, suddenly. "Is it necessary to
sit back and wait for this unknown to strike again?"
"Ordinarily," Kennedy replied, "on a case like this it has been my custom to permit the
guilty parties to betray themselves, as they will do inevitably--especially when I call to
my aid the recent discoveries of science for the detection and measurement of fine and
almost imperceptible shades of emotion. But now that I realize the presence of this
menace I shall become a detective of action; in fact, I shall not stop at any course to hurry
matters. The very first thing in the morning I shall go to the studio and I want you and
Jameson along. I"--his eyes twinkled; it was the excitement at the prospect--"I may need
considerable help in getting the evidence I wish."
"Which is--?" It was I who interposed the question.
Kennedy blew a cloud of smoke. "There are three ways of tracing down a crime, aside
from the police method of stool pigeons to betray the criminals and the detective bureau
method of cross- examination under pressure, popularly known as the third degree."
"What are they?" Mackay asked, unaware that Kennedy needed little prompting once he
felt inclined to talk out some matter puzzling him.
"One is the process of reasoning from the possible suspects to the act itself--in other
words, putting the emphasis on the motive. A second is the reverse of the first, involving
a study of the crime for clues and making deductions from the inevitable earmarks of the
person for the purpose of discovering his identity. The third method, except for some
investigations across the water, is distinctly my own, the scientific.
"In all sciences," Kennedy went on, warming to his subject, "progress is made by a
careful tabulation of proved facts. The scientific method is the method of exact
knowledge. Thus, in crime, those things are of value to us which by an infinite series of
empiric observations have been established and have become incontrovertible. The