days.
Anyhow, I'll be back in a week, and you mustn't worry about me a single
minute."

"How are you going?" inquired his father, in the gentle, soothing tone
persons use in addressing maniacs.

"Through the air," said Rob.

His father groaned.

"Where's your balloon?" inquired sister Mabel, sarcastically.

"I don't need a balloon," returned the boy. "That's a clumsy way of
traveling, at best. I shall go by electric propulsion."

"Good gracious!" cried Mr. Joslyn, and the mother murmured: "My poor
boy! my poor boy!"

"As you are my nearest relatives," continued Rob, not noticing these
exclamations, "I will allow you to come into the back yard and see me
start. You will then understand something of my electrical powers."

They followed him at once, although with unbelieving faces, and on the
way Rob clasped the little machine to his left wrist, so that his coat
sleeve nearly hid it.

When they reached the lawn at the back of the house Rob kissed them all
good-by, much to his sisters' amusement, and turned the indicator of
the little instrument to the word "up."

Immediately he began to rise into the air.

"Don't worry about me!" he called down to them. "Good-by!"

Mrs. Joslyn, with a scream of terror, hid her face in her hands.

"He'll break his neck!" cried the astounded father, tipping back his
head to look after his departing son.

"Come back! Come back!" shouted the girls to the soaring adventurer.

"I will--some day!" was the far-away answer.

Having risen high enough to pass over the tallest tree or steeple, Rob
put the indicator to the east of the compass-dial and at once began
moving rapidly in that direction.

The sensation was delightful. He rode as gently as a feather floats,
without any exertion at all on his own part; yet he moved so swiftly
that he easily distanced a railway train that was speeding in the same
direction.

"This is great!" reflected the youth. "Here I am, traveling in fine
style, without a penny to pay any one! And I've enough food to last me
a month in my coat pocket. This electricity is the proper stuff, after
all! And the Demon's a trump, and no mistake. Whee-ee! How small
everything looks down below there. The people are bugs, and the houses
are soap-boxes, and the trees are like clumps of grass. I seem to be
passing over a town. Guess I'll drop down a bit, and take in the
sights."

He pointed the indicator to the word "down," and at once began dro