And now, as they waited, suddenly a sinister tinge of orange suffused the rosy hues of the east.
“The Fire Ants!” cried Joan, shrinking. “They’ve seen us! They’re coming!”
It was true, Jim saw with a heavy heart.
Turning to Professor Wentworth, he gasped out:
“Quick! We’ve got to do something! You’ve no idea how fast they move!”
“Very well.” The professor’s voice was strangely calm. “You may start your motor. I shall do what I can. Though if we only had the sun—”
Jim leaped for the cabin.
A touch of the starter and the powerful engine came in. Braking his wheels hard, to hold the plane on the ground, he advanced the throttle as much as he dared, and sent a high-tension current surging through the wires the professor had connected with his tube above.
Soon came that high, whining hum they had heard in the laboratory—a thousand times magnified now—and the nib of the big tube glowed a livid, eery green in the lemon dawn.
“Joan!” called her father sharply. “Get in the cabin with Jim!”