Nevertheless there was no sound from the detectaphone which would indicate that he had overheard and was spreading the alarm. He was there yet, for we could hear him clear his throat once or twice.
"No," replied Kennedy calmly, "he knows nothing about it. I didn't use any ordinary means to prepare against the experts who have brought this situation about. That message you heard me send went out over what we call the 'phantom circuit.'"
"The phantom circuit?" repeated Brixton, chafing at the delay.
"Yes, it seems fantastic at first, I suppose," pursued Kennedy calmly; "but, after all, it is in accordance with the laws of electricity. It's no use fretting and fuming, Mr. Brixton. If Janeff can wait, we'll have to do so, too. Suppose we should start and this Kronski should change his plans at the last minute? How would we find it out? By telepathy? Believe me, sir, it is better to wait here a minute and trust to the phantom circuit than to mere chance."
"But suppose he should cut the line," I put in.
Kennedy smiled. "I have provided for that, Walter, in the way I installed the thing. I took good care that we could not be cut off that way. We can hear everything ourselves, but we cannot be overheard. He knows nothing. You see, I took advantage of the fact that additional telephones or so-called phantom lines can be superposed on existing physical lines. It is possible to obtain a third circuit from two similar metallic circuits by using for each side of this third circuit the two wires of each of
