came nerve-torturing, piling up like a wave that refuses to break and fall.
"It's useless!" cried the girl.
McKinnon silenced her with a peremptory movement of the hand.
"Wait!" he commanded.
He leaned forward, slowly, until his breast-bone pressed against the edge of the table. Then came a moment or two of unbroken quietness.
"I've got them!" he whispered.
But still again the silence was unbroken as the man with the glimmering steel band across his head sat crooked up like a schoolboy over a slate, listening. His hand went out to the lever-heads in the numeral-lined slots of his tuning-box, as he paused to tune up to the wave-pitch of some as yet undecipherable message. His half-closed eyes opened and widened, and he was suddenly springing for the switch-handle of his starting-box again.
"I've got them," he cried exultantly, as he turned to his key. "I've got two of them!"
"Two of them?"
"Yes; they're both talking at once. I've got to make one hold back, if I can reach him. If not, I've got to tune him out!"
His voice was cut off by the familiar spit and flash of the huge blue spark, and a thin ozonic
