"That requires some thought," returned the Demon, and paused for
several moments, while Rob feasted his eyes upon the gorgeous rays of
color that flashed and vibrated in every direction and surrounded the
figure of his visitor with an intense glow that resembled a halo.

Then the Demon raised his head and said:

"The thing most necessary to man is food to nourish his body.  He
passes a considerable part of his life in the struggle to procure
food, to prepare it properly, and in the act of eating.  This is not
right.  Your body can not be very valuable to you if all your time is
required to feed it.  I shall, therefore, present you, as my first
gift, this box of tablets.  Within each tablet are stored certain
elements of electricity which are capable of nourishing a human body
for a full day.  All you need do is to toss one into your mouth each
day and swallow it.  It will nourish you, satisfy your hunger and
build up your health and strength.  The ordinary food of mankind is
more or less injurious; this is entirely beneficial.  Moreover, you
may carry enough tablets in your pocket to last for months."

Here he presented Rob the silver box of tablets, and the boy, somewhat
nervously, thanked him for the gift.

"The next requirement of man," continued the Demon, "is defense from
his enemies.  I notice with sorrow that men frequently have wars and
kill one another.  Also, even in civilized communities, man is in
constant danger from highwaymen, cranks and policemen.  To defend
himself he uses heavy and dangerous guns, with which to destroy his
enemies.  This is wrong.  He has no right to take away what he can not
bestow; to destroy what he can not create.  To kill a fellow-creature
is a horrid crime, even if done in self-defense.  Therefore, my second
gift to you is this little tube.  You may carry it within your pocket.
Whenever an enemy threatens you, be it man or beast, simply point the
tube and press this button in the handle.  An electric current will
instantly be directed upon your foe, rendering him wholly unconscious
for the period of one hour.  During that time you will have
opportunity to escape.  As for your enemy, after regaining
consciousness he will suffer no inconvenience from the encounter
beyond a slight headache."

"That's fine!" said Rob, as he took the tube.  It was scarcely six
inches long, and hollow at one end.

"The busy lives of men," proceeded the Demon, "require them to move
about and travel in all directions.  Yet to assist them there are only
such crude and awkward machines as electric trolleys, cable cars,
steam railways and automobiles.  These crawl slowly over the uneven
surface of the earth and frequently get out of order.  It has grieved
me that men have not yet discovered what even birds know: that the
atmosphere offers them swift and easy means of traveling from one part
of the earth's surface to another."

"Some people have tried to build airships," remarked Rob.

"So they have; great, unwieldy machines which offer so much resistance
to the air that they are quite useless.  A big machine is not needed
to carry one through the air.  There are forces in nature which may be
readily used for such purpose.  Tell me, what holds you to the Earth,
and makes a stone fall to the ground?"

"Attraction of gravitation," said Rob, promptly.

"Exactly.  That is one force I refer to," said the Demon.  "The force
of repulsion, which is little known, but just as powerful, is another
that mankind may direct.  Then there are the Polar electric forces,
attracting objects toward the north or south poles.  You have guessed
something of this by the use of the compass, or electric needle.
Opposed to these is centrifugal electric force, drawing objects from
east to west, or in the opposite direction.  This force is created by
the whirl of the earth upon its axis, and is easily utilized, although
your scientific men have as yet paid little attention to it.

"These forces, operating in all directions, absolute and immutable,
are at the disposal of mankind.  They will carry you through the
atmosphere wherever and whenever you choose.  That is, if you know
how to control them.  Now, here is a machine I have myself perfected."

The Demon drew from his pocket something that resembled an open-faced
watch, having a narrow, flexible band attached to it.

"When you wish to travel," said he, "attach this little machine to
your left wrist by means of the band.  It is very light and will not
be in your way.  On this dial are points marked 'up' and 'down' as well
as a perfect compass.  When you desire to rise into the air set the
indicator to the word 'up,' using a finger of your right hand to turn
it.  When you have risen as high as you wish, set the indicator to the
point of the compass you want to follow and you will be carried by the
proper electric force in that direction.  To descend, set the
indicator to the word 'down.'  Do you understand?"

"Perfectly!" cried Rob, taking the machine from the Demon with
unfeigned delight.  "This is really wonderful, and I'm awfully obliged
to you!"

"Don't mention it," returned the Demon, dryly.  "These three gifts you
may amuse yourself with for the next week.  It seems hard to entrust
such great scientific discoveries to the discretion of a mere boy; but
they are quite harmless, so if you exercise proper care you can not
get into trouble through their possession.  And who knows what
benefits to humanity may result?  One week from to-day, at this hour,
I will again appear to you, at which time you shall receive the second
series of electrical gifts."

"I'm not sure," said Rob, "that I shall be able again to make the
connections that will strike the Master Key."

"Probably not," answered the Demon.  "Could you accomplish that, you
might command my services forever.  But, having once succeeded, you
are entitled to the nine gifts--three each week for three weeks--so
you have no need to call me to do my duty.  I shall appear of my
own accord."

"Thank you," murmured the boy.

The Demon bowed and spread his hands in the form of a semi-circle.  An
instant later there was a blinding flash, and when Rob recovered from
it and opened his eyes the Demon of Electricity had disappeared.

4.  Testing the Instruments

There is little doubt that this strange experience befallen a grown
man he would have been stricken with a fit of trembling or a sense of
apprehension, or even fear, at the thought of having faced the
terrible Demon of Electricity, of having struck the Master Key of the
world's greatest natural forces, and finding himself possessed of
three such wonderful and useful gifts.  But a boy takes everything as
a matter of course.  As the tree of knowledge sprouts and expands
within him, shooting out leaf after leaf of practical experience, the
succession of surprises dulls his faculty of wonderment.  It takes a
great deal to startle a boy.

Rob was full of delight at his unexpected good fortune; but he did not
stop to consider that there was anything remarkably queer or uncanny
in the manner in which it had come to him.  His chief sensation was
one of pride.  He would now be able to surprise those who had made
fun of his electrical craze and force them to respect his marvelous
powers.  He decided to say nothing about the Demon or the accidental
striking of the Master Key.  In exhibiting to his friends the
electrical devices he had acquired it would be "no end of fun" to mark
their amazement and leave them to guess how he performed his feats.

So he put his treasures into his pocket, locked his workshop and went
downstairs to his room to prepare for dinner.

While brushing his hair he remembered it was no longer necessary for
him to eat ordinary food.  He was feeling quite hungry at that moment,
for he had a boy's ravenous appetite; but, taking the silver box from
his pocket, he swallowed a tablet and at once felt his hunger as fully
satisfied as if he had partaken of a hearty meal, while at the same
time he experienced an exhilarating glow throughout his body
and a clearness of brain and gaiety of spirits which filled him
with intense gratification.

Still, he entered the dining-room when the bell rang and found his
father and mother and sisters already assembled there.

"Where have you been all day, Robert?" inquired his mother.

"No need to ask," said Mr. Joslyn, with a laugh.  "Fussing over
electricity, I'll bet a cookie!"

"I do wish," said the mother, fretfully, "that he would get over that
mania.  It unfits him for anything else."

"Precisely," returned her husband, dishing the soup; "but it fits him
for a great career when he becomes a man.  Why shouldn't he spend his
summer vacation in pursuit of useful knowledge instead of romping
around like ordinary boys?"

"No soup, thank you," said Rob.

"What!" exclaimed his father, looking at him in surprise, "it's your
favorite soup."

"I know," said Rob, quietly, "but I don't want any."

"Are you ill, Robert?" asked his mother.

"Never felt better in my life," answered Rob, truthfully.

Yet Mrs. Joslyn looked worried, and when Rob refused the roast, she
was really shocked.

"Let me feel your pulse, my poor boy!" she commanded, and wondered to
find it so regular.

In fact, Rob's action surprised them all.  He sat calmly throughout
the meal, eating nothing, but apparently in good health and spirits,
while even his sisters regarded him with troubled countenances.

"He's worked too hard, I guess," said Mr. Joslyn, shaking his head sadly.

"Oh, no; I haven't," protested Rob; "but I've decided not to eat
anything, hereafter.  It's a bad habit, and does more harm than good."

"Wait till breakfast," said sister Helen, with a laugh; "you'll be
hungry enough by that time."

However, the boy had no desire for food at breakfast time, either, as