you say, it may be that the house is going to be rented. It's too
valuable a property to let stand idle. Did you hear how long Andy
was going to stay?"

"A week, I believe."

"A week! Say, one day would be enough I should think."

"You must have some special reason for being afraid Andy will do you
some harm," exclaimed Ned. "Out with it, Tom."

"Well, I'll tell you what it is, Ned," and Tom led his chum inside
the shop, in front of which the two lads had been talking. It was a
shop where the young inventor constructed many of his marvelous
machines, aircraft, and instruments of various sorts.

"Do you think some one may hear you?" asked Ned.

"They might. I'm not taking any chances. But the reason I want to be
especially careful that Andy Foger doesn't spy on any of my
inventions is that at last I have perfected my noiseless airship
motor!"

"You have!" cried Ned, for he knew that his chum had been working
for a long time on this motor, that would give out no sound, no
matter at how high a speed it was run. "That's great, Tom! I
congratulate you. I don't wonder you don't want Andy to get even a
peep at it."

"Especially as I haven't it fully patented," went on the young