ious
other apparatuses, machines, and appliances, the nature of which Tom
could not readily gather from a mere casual view.

"Well, what's your opinion, now that you have seen the motor?" asked
Mr. Fenwick, anxiously.

"I'd have to see it in operation," said Tom.

"And you shall, right after dinner," declared the inventor. "I'd
like to start it now, and hear what you have to say, but I'm not so
selfish as that. I know you must be hungry after your trip from
Shopton, as they say aeroplaning gives one an appetite."

"I don't know whether it's that or not," answered Tom with a laugh,
"but I am certainly hungry."

"Then we'll postpone the trial until after dinner. It must be ready
by this time, I think," said Mr. Fenwick, as he led the way back to
the house. It was magnificently furnished, for the inventor was a
man of wealth, and only took up aeroplaning as a "fad." An excellent
dinner was served, and then the three returned once more to the shed
where the WHIZZER was kept.

"Shall I start the motor in here?" asked Mr. Fenwick, when he had
summoned several of the machinists whom he employed, to aid himself
and the young inventor.

"It would be better if we could take it outside," suggested Tom,
"yet a crowd is sure to gather, and I don't like to work in a mob of
people."

"Oh, we can easily get around that," said Mr. Fenwick. "I have two
openings to my aeroplane shed. We can take the WHIZZER out of the
rear door, into a field enclosed by a high fence. That is where I
made all my trials, and the crowd couldn't get in, though some boys
did find knot-holes and use them. But I don't mind that. The only
thing that bothers me is that I can't make the WHIZZER go up, and if
it won't go up, it certainly won't sail. That's my difficulty, and I
hope you can remedy it, Tom Swift."

"I'll do the best I can. But let's get the airship outside."

This was soon accomplished, and in the open lot Tom made a thorough
and careful examination of the mechanism. The motor was started, and
the propellers, for there were two, whirled around at rapid speed.

Tom made some tests and calculations, at which he was an expert, and
applied the brake test, to see how much horse power the motor would
deliver.

"I think there is one trouble that we will have to get over," he
finally said to Mr. Fenwick.

"What is that?"

"The motor is not quite powerful enough because of the way in which
you have it geared up. I think by changing some of