No dots or dashes, as the operator had said, but the signal was strong. It rose and fell and wavered into shrill tremolos, a ghostly, unearthly sound, and it kept on and on in a shrill despairing wail. Abruptly it stopped.
The captain would have removed the receiver from his ear, but the operator stopped him. "Listen," he said, "to the answer."
here was silence, broken only by an occasional hiss and crackle of some far distant mountain storm. Then, faint as a whisper, came an answering, whistling breath.
It, too, trembled and quavered. It went up—up—to the limit of hearing; then slid down the scale to catch and tremble and again ascend in endless unvarying ups and downs of sound. It was another unbroken, unceasing, but always changing vibration.
"What in thunder is that?" Captain Blake demanded.
"Communication of some sort, I should say," McGuire said slowly, and he caught the operator's eyes upon him in silent agreement.
"No letters," Blake objected; "no breaks; just that screech." He listened again. "Darned if it doesn't almost seem to say something," he admitted.
"When did you first hear this?" he demanded of the radio man.