Forward, almost exactly like the front set of wings of the dragon fly, was the large, main plane, with the concave turn toward the ground.  There was the usual propeller in front, operated by a four cylinder motor, the cylinders being air cooled, and set like the spokes of a wheel around the motor box.  The big gasolene tank, and other mechanism was in front of the right-hand operator’s seat, where Tom always rode.  He had seldom taken a passenger up with him, though the machine would easily carry two, and he was a little nervous about the outcome of the trip with Mr. Damon.

“How do you like the looks of it?” asked the young inventor, as he wheeled the butterfly out of the shed, and began pumping up the tires of the bicycle wheels on which it ran over the ground, to get impetus enough with which to rise.

“It looks a little frail, compared to the big Red cloud, Tom,” answered the eccentric man, “but I’m going up in her just the same; bless my buttons if I’m not.”

Tom could not but admire the grit of his friend.

The rest of the day was busily spent making various adjustments to the monoplane, putting on new wire stays, changing the rudder cables, and tuning up the motor.  The propeller was tightened on the shaft, and toward evening Tom announced that all was in readiness for a trial flight.

“Want to come, Mr. Damon?” he asked.

“I’ll wait, and see how it acts with you aboard,” was the answer.  “Not that I’m afraid, for I’m going to make the trip in the morning, but perhaps it won’t work just right now.”

“Oh, I guess it will,” ventured Tom, and in order to be able to know just how his butterfly was going to behave, with a passenger of Mr. Damon’s weight, the young inventor placed a bag of sand on the extra seat.

The monoplane was then wheeled to the end of the starting ground.  Tom took his place in the seat, and Mr. Jackson started the propeller.  At first the engine failed to respond, but suddenly with a burst of smoke, and a spluttering of fire the cylinders began exploding.  The hat of Mr. Damon, who was standing back of the machine, was blown off by the wind created by the propeller.

“Bless my gaiters!” he exclaimed, “I never thought it was as strong as that!”

“Let go!” cried Tom to Mr. Jackson and Eradicate, who were holding back the monoplane from gliding over the ground.

“All right,” answered the engineer.

An instant later the explosions almost doubled, for Tom turned on more gasolene.  Then, like some live thing, the butterfly rushed across the starting ground.  Faster and faster it went, until the young inventor, knowing that he had motion enough, tilted his planes to catch the wind.

Up he went from earth, like some graceful bird, higher and higher, and then, in a big spiral, he began ascending until he was five hundred feet in the air.  Up there he traveled back and forth, in circles, and in figure eights, desiring to test the machine in various capacities.