Dian the Beautiful was among them. She is Dave Innes's mate.

"Do you think it will fly?" she asked Innes.

"No."

"Then why risk your life?"

"If it doesn't fly, there will be no risk; and it will please Abner if I try," he replied.

"There will be no honor," she said, "for it will not be the first aeroplane to fly over Pellucidar. The great ship that you called a dirigible brought a plane. Was it not Jason Gridley who flew it until it was brought down by a thipdar?"

They were walking around the plane examining it carefully. The frame of the single parachute-like wing was of bamboo: the "fabric" was fabricated of the peritoneum of a large dinosaur. It was a thin, transparent membrane well suited to the purpose. The cockpit was set down into the top of the wing; the motor stuck out in front like a sore thumb; and behind a long tail seemed to have been designed to counter-balance the weight of the engine. It carried the stabilizers, fin, rudder, and elevators.

The engine, the first gas engine built in Pellucidar, was, an achievement of the first magnitude. It had been built practically by hand by men of the stone age, under the direction of Perry, and without precision instruments.

"Will it run?" asked Innes.

"Of course it will run," replied Perry. "It is, I will concede, a trifle noisy; and is susceptible to some refinements, but a sweet thing nevertheless."

"I hope so," said Innes.

"Are you ready, David?" asked the inventor.

"Quite," replied Innes.

"Then climb into the cockpit and I'll explain the controls to you. You will find everything very simple."

Ten minutes later Innes said he knew all about flying the ship that he would ever know, and Perry climbed down to the ground.

"Everybody get out of the way!" he shouted. "You are about to witness the beginning of a new epoch in the history of Pellucidar."

A mechanic took his place at the propeller. It was so far off the ground that he had to stand on a specially constructed ladder. A man on either side stood ready to pull the blocks from beneath the wheels.

"Contact!" shouted Perry.

"Contact!" replied Innes.

The man at the propellor gave it a turn. The engine spluttered and died. "By golly!" exclaimed Innes! "It really fired. Try it again."

"Give her more throttle," said Perry.

The mechanic spun her again, and this time the engine took hold. The mechanic leaped from the ladder and dragged it away. David opened the throttle a little wider, and the engine almost leaped from its seat. It sounded as though a hundred men were building a hundred boilers simultaneously.

David shouted to the two men to pull the blocks, but no one could hear him above the din of the motor. He waved and pointed and signalled, and finally Perry grasped what he wanted, and had the blocks withdrawn. Everyone stood in wide-eyed silence as David opened the throttle wider. The engine raced. The plane moved! But it moved backward! It swung around and nearly crashed into the crowd of Sarians before Innes could cut the motor.

Perry approached, scratching his head. "What in the world did you do, David," he asked, "to make an aeroplane back up?"

Dave Innes laughed.

"What are you laughing at?" demanded Perry. "Don't you realize that we may have stumbled upon something sensational in aerodynamics? Just think of a fighter plane that could go either forward or backward! just think of how it could dodge enemy planes! Think of its maneuverability! What did you do, David?"

"The honor is wholly yours, Abner," replied Innes. "You did it."

"But how did I do it?"

"You've reversed the pitch of your propeller blades. The plane cannot go in any other direction than backward."

"Oh," said Perry, weakly.

"But it does move," said Innes, encouragingly, "and the fault is easily remedied."

There being no such thing as time in Pellucidar, no, one cared how long it took to effect a change in the propeller. Everyone except Perry and a couple of his mechanics lay down in the shade, under trees or under the plane until Perry announced that the propeller had been reversed.

Innes took his place in the cockpit, a mechanic spun the prop, the engine started, the blocks were yanked away. The engine roared and pounded and leaped.