The bare area seemed to run all down a long valley and spread out as it rounded the crest of a hill which hid what lay behind it from their view. As they watched a grey speck that might have been an ant at that height and distance, lumbered slowly down the valley, and then Ben noticed a tiny flicker of red light, so bright as to be clearly visible even in the day, where the grey speck moved against the hillside. A door seemed to open in the hillside; focusing the glasses the aviator handed him, he could just make out a square, bulky object that trundled forth. And then one—two—three—four—five of the huge dodo-tetrapteryx birds shot out, poised for a moment, and leaped into flight.
"Hello, Brisbane," called Ben into the radiophone. "Five dodos have taken off from the cutting in the hills. I think they are after us. Better turn back this way and get ready for trouble."
The aviator, understanding without being warned, had turned the plane. Ben swung round to look over his shoulder. The dodos were already some yards in the air; behind them the bulky object was running slowly out of the opening in the hillside. It had the appearance of a very long, flexible cannon. As he held his glasses on it, it stopped, straightened out and the muzzle was elevated in their direction.
"Dive!" he shouted suddenly into the voice-tube, entirely on impulse. The airplane banked sharply and seemed to drop straight down, and at the same instant right through the spot where they had just passed shot a beam of light so brilliant that it outshone the morning sun. There was a roar louder than that of the motor; the plane pitched and heaved in the disturbed air, and the light-beam went off as suddenly as it had snapped on.
"Didn't I tell you those babies were poison?" he remarked. "Boy, if that ever hit us!"
"What was it?" asked the aviator's voice.
"Don't know, but it was something terrible. Let's head for home and mamma. I don't care about this."
The plane reeled as the pilot handled the controls. Rrrr! said something and the light-beam shot out again, just to one side this time. Out of the corner of his eye Ben could see one of the birds—gaining on them!
"How do you work this machine-gun?" he asked.
"Just squeeze the trigger. Look out! I'm going to dive her again."