tier of seats
that made a sort of little amphitheatre out of his lecture-room his
stereopticon sputtered.

"Moving pictures to-night, eh?" said Inspector O'Connor.

"Not exactly," said Craig, "though--yes, they will be moving in another
sense. Now, if we are all ready, I'll switch off the electric lights."

The calcium sputtered some more, and a square of light was thrown on the
sheet.

Kennedy snapped a little announcer such as lecturers use. "Let me invite
your attention to these enlargements of finger-prints," he began, as
a huge thumb appeared on the screen. "Here we have a series of
finger-prints which I will show one after another slowly. They are all
of the fingers of the same person, and they were found on some empty
bottles of spring water used at Bisbee Hall during the two weeks
previous to the departure of Mr. Bisbee for New York.

"Here are, in succession, the finger-prints of the various servants
employed about the house--and of a guest," added Craig, with a slight
change of tone. "They differ markedly from the finger-prints on the
glass," he continued, as one after another appeared, "all except this
last one. That is identical. It is, Inspector, what we call a composite
type of finger-print--in this case a combination of what is called the
'loop' and 'whorl' types."

No sound broke the stillness save the sputtering of the oxygen on the
calcium of the stereopticon.

"The owner of the fingers from which these prints were made is in this
room. It was from typhoid germs on these fingers that the fever was
introduced into the drinking water at Bisbee Hall."

Kennedy paused to emphasise the statement, then continued. "I am now
going to ask Dr. Leslie to give us a little talk on a recent discovery
in the field of typhoid fever--you understand, Commissioner, what I
mean, I believe?"

"Perfectly. Shall I mention names?"

"No, not yet."

"Well," began Dr. Leslie, clearing his throat, "within the past year or
two we have made a most weird and startling discovery in typhoid fever.
We have found what we now call 'typhoid carriers'--persons who do not
have the disease themselves, perhaps never have had it, but who are
literally living test-tubes of the typhoid bacillus. It is positively
uncanny. Everywhere they go they scatter the disease. Down at the
department we have the records of a number of such instances, and our
men in the research laboratories have come to the conclusion that, far
from being of r