"Wait a minute, give it a chance," urged Tom. "By the way, how about
that tuning device, have you tried that yet?"

"No, good gracious, my head must be turning into solid ivory from the
neck up. I guess that's just what the trouble is."

Jack began carefully sliding a small block connected to the
instruments up and down the coiled wire which formed the tuning
apparatus, and brought the sending and receiving ends into harmony
just as if they had been two musical instruments. When the right
electric "chord" was struck he should be able to hear, just as in
wireless he would be able to catch the message of an instrument whose
wave lengths were attuned to his.

Suddenly Tom saw his chum and cousin give a start and then a shout.
Over the space between the workshop and the small shed a human voice
had been borne on electric waves. Sharp and clear as though he had
been listening to a "wire" 'phone, Jack caught and recognized his
father's voice:

"Hul-lo!"




CHAPTER VI.

THE RADIO TELEPHONE.