connection with the camera, in order that
night views might be taken. Besides being automatic the camera could be
worked by hand.

When it was not necessary to have the camera operate by the storage
battery, it could be connected to wires and worked by an ordinary set
of batteries, or by a dynamo. This was for use on the airship, where
there was a big electrical machine. I shall tell you more about the
camera as the story proceeds.

One afternoon Tom was alone in the shop, for he had sent Koku on an
errand, and Eradicate was off in a distant part of the grounds, doing
some whitewashing, which was his specialty. Ned had not come over, and
Mr. Swift, having gone to see some friends, and Mrs. Baggert being at
the store, Tom, at this particular time, was rather isolated.

He was conducting some delicate electrical experiments, and to keep the
measuring instruments steady he had closed all the windows and doors of
his shop. The young inventor was working at a bench in one corner, and
near him, standing upright, was a heavy shaft of iron, part of his
submarine, wrapped in burlap, and padded, to keep it from rusting.

"Now," said Tom to himself, as he mixed two kinds of acid in a jar, to
produce a new sort of electrical current, "I will see if this is any
better than the first way in which I did it."

He was careful about pouring out the powerful stuff, but, in spite of
this, he spilled a drop on his finger. It burned like fire, and,
instinctively, he jerked his hand back.

The next instant there was a series of happenings. Tom's elbow came in
contact with another jar of acid, knocking it over, and spilling it
into the retort where he had been mixing the first two liquids. There
was a hissing sound, as the acids combined, and a thick, white vapor
arose, puffing into Tom's face, and making him gasp.

He staggered back, brushed against the heavy iron shaft in the corner,
and it fell sideways against him, knocking him to the floor, and
dropping across his thighs. The padding on it saved him from broken
bones, but the shaft was so heavy, that after it was on him, Tom could
not move. He was held fast on the floor of his shop, unable to use his
legs, and prevented from getting up.

For a moment Tom was stunned, and then he called:

"Help! Help! Eradicate! Koku! Help!"

He waited a moment, but there was only a silence.

And then Tom smelled a strange odor--an odor of a choking gas that
seemed to smother him.

"It's th