I was quite as much interested as Waldon.  “In wireless,” he went on, “the signals are not sent in one direction, but in all, so that a person within range of the ethereal disturbance can get them if only he has the necessary receiving apparatus.  This apparatus need not be so elaborate and expensive as used to be thought needful if a sensitive detector is employed, and I have sent over to the station for a new piece of apparatus which I knew they had in almost any Marconi station.  Why, I’ve got wireless signals using only twelve feet of number eighteen copper wire stretched across a room and grounded with a water pipe.  You might even use a wire mattress on an iron bedstead.”

“Can’t they find out by—­er, interference?” I asked, repeating the term I had so often heard.

Kennedy laughed.  “No, not for radio apparatus which merely receives radiograms and is not equipped for sending.  I am setting up only one side of a wireless outfit here.  All I want to do is to hear what is being said.  I don’t care about saying anything.”

He unwrapped another package which had been loaned to him by the radio station and we watched him curiously as he tested it and set it up.  Some parts of it I recognized such as the very sensitive microphone, and another part I could have sworn was a phonograph cylinder, though Craig was so busy testing his apparatus that now we could not ask questions.

It was late in the afternoon when he finished, and we had just time to run up to the dock at Seaville and stop off at the Lucie to see if anything had happened in the intervening hours before dinner.  There was nothing, except that I found time to file a message to the Star and meet several fellow newspaper men who had been sent down by other papers on the chance of picking up a good story.

We had the Nautilus to ourselves, and as she was a very comfortable little craft, we really had a very congenial time, a plunge over her side, a good dinner, and then a long talk out on deck under the stars, in which we went over every phase of the case.  As we discussed it, Waldon followed keenly, and it was quite evident from his remarks that he had come to the conclusion that Dr. Jermyn at least knew more than he had told about the case.

Still, the day wore away with no solution yet of the mystery.

CHAPTER IX

THE RADIO DETECTIVE

It was early the following morning when a launch drew up beside the Nautilus.  In it were Edwards and Dr. Jermyn, wildly excited.

“What’s the matter?” called out Waldon.

“They—­they have found the body,” Edwards blurted out.

Waldon paled and clutched the rail.  He had thought the world of his sister, and not until the last moment had he given up hope that perhaps she might be found to have disappeared in some other way than had become increasingly evident.

“Where?” cried Kennedy.  “Who?”