Hal Dane moistened dry lips, shaped his mouth to whistle, and at last forced out a shrill sound. He had seen steady whistling charm small animals like rabbits and foxes into a momentary "freeze". He prayed, that it would work now. Dry-mouthed or not, he must keep up this shrilling ten seconds, twenty seconds--till his hand could lift his revolver from its hip holster, till he could take aim.