t 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 be