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.