en at Wuerzburg
about seven years, and had made no discoveries which he considered of
great importance prior to the one under consideration. These details
were given under good-natured protest, he failing to understand why his
personality should interest the public. He declined to admire himself or
his results in any degree, and laughed at the idea of being famous. The
professor is too deeply interested in science to waste any time in
thinking about himself. His emperor had feasted, flattered, and
decorated him, and he was loyally grateful. It was evident, however,
that fame and applause had small attractions for him, compared to the
mysteries still hidden in the vacuum tubes of the other room.

"Now, then," said he, smiling, and with some impatience, when the
preliminary questions at which he chafed were over, "you have come to
see the invisible rays."

"Is the invisible visible?"

"Not to the eye; but its results are. Come in here."

[Illustration: BONES OF A HUMAN FOOT PHOTOGRAPHED THROUGH THE FLESH

From a photograph by A. A. C. Swinton, Victoria Street, London.
Exposure, fifty-five seconds]

He led the way to the other square room mentioned, and indicated the
induction coil with which his researches were made, an ordinary
Ruhmkorff coil, with a spark of from four to six inches, charged by a
current of twenty amperes. Two wires led from the coil, through an open
door, into a smaller room on the right. In this room was a small table
carrying a Crookes tube connected with the coil. The most striking
object in the room, however, was a huge and mysterious tin box about
seven feet high and four feet square. It stood on end, like a huge
packing case, its side being perhaps five inches from the Crookes tube.

The professor explained the mystery of the tin box, to the effect that
it was a device of his own for obtaining a portable dark-room. When he
began his investigations he used the whole room, as was shown by the
heavy blinds and curtains so arranged as to exclude the entrance of all
interfering light from the windows. In the side of the tin box, at the
point immediately against the tube, was a circular sheet of aluminum one
millimetre in thickness, and perhaps eighteen inches in diameter,
soldered to the surrounding tin. To study his rays the professor had
only to turn on the current, enter the box, close the door, and in
perfect darkness inspect only such light or light effects as he had a
right to consider hi