But it served to warn their quarry of their presence. He must have whirled to get a look at them, for the sled wobbled crazily for an instant.
He dipped out of sight behind a dune and was gone when they reached the spot. Dunes blocked sight in all directions and a dozen paths branched out between them.
"Over there!" Nathan pointed to a fine sand cloud that betrayed the presence of the sled beyond the dunes.
Firebird followed and soon they came in sight again. Nathan fired another shot that went wide because of the plunging motion of the sled. Then the enemy suddenly plunged into the depths of an immense blow hole.
Firebird swung wide of the hole. Nathan glanced at her in puzzlement. "Where are you going?"
"Not down there. It would be fatal to get into a dog fight around the sides of that blow hole. We'll wait for him to come out and hope it is somewhere near us."
From the top of a small dune they caught sight of the other sled speeding around the inside of the hole. But he knew he had failed to lure them into it where he would have had as good chance as they. He sped up and over the edge opposite them.
Firebird started the sled moving again. Nathan kept his eye on the enemy. Even as he watched the other paused. "He's not running away. He's going to turn and fight!"
Firebird held her speed down and let the other build up. He came in shooting. Puffs of flame spurted from the small lance he was firing through the port.
Nathan raised the rifle and fired. The shot struck midway between the motor and the cabin and the enemy sled burst into flames.