s own, hiding his light, in fact, not under the
Biblical bushel, but in a more commodious box.

"Step inside," said he, opening the door, which was on the side of the
box farthest from the tube. I immediately did so, not altogether certain
whether my skeleton was to be photographed for general inspection, or my
secret thoughts held up to light on a glass plate. "You will find a
sheet of barium paper on the shelf," he added, and then went away to the
coil. The door was closed, and the interior of the box became black
darkness. The first thing I found was a wooden stool, on which I
resolved to sit. Then I found the shelf on the side next the tube, and
then the sheet of paper prepared with barium platinocyanide. I was thus
being shown the first phenomenon which attracted the discoverer's
attention and led to his discovery, namely, the passage of rays,
themselves wholly invisible, whose presence was only indicated by the
effect they produced on a piece of sensitized photographic paper.

A moment later, the black darkness was penetrated by the rapid snapping
sound of the high-pressure current in action, and I knew that the tube
outside was glowing. I held the sheet vertically on the shelf, perhaps
four inches from the plate. There was no change, however, and nothing
was visible.

"Do you see anything?" he called.

"No."

"The tension is not high enough;" and he proceeded to increase the
pressure by operating an apparatus of mercury in long vertical tubes
acted upon automatically by a weight lever which stood near the coil. In
a few moments the sound of the discharge again began, and then I made my
first acquaintance with the Roentgen rays.

The moment the current passed, the paper began to glow. A yellowish
green light spread all over its surface in clouds, waves and flashes.
The yellow-green luminescence, all the stranger and stronger in the
darkness, trembled, wavered, and floated over the paper, in rhythm with
the snapping of the discharge. Through the metal plate, the paper,
myself, and the tin box, the invisible rays were flying, with an effect
strange, interesting and uncanny. The metal plate seemed to offer no
appreciable resistance to the flying force, and the light was as rich
and full as if nothing lay between the paper and the tube.

"Put the book up," said the professor.

I felt upon the shelf, in the darkness, a heavy book, two inches in
thickness, and placed this against the plate. It made no differenc