CHAPTER IX.--LINE AND WIRELESS TELEGRAPHS 190

A GROUND TELEGRAPH -- HOW TO TALK FROM HOUSE TO HOUSE -- THE MORSE TELEGRAPH CODE -- A STORY OF EDISON -- HOW DETECTIVES USED THE CODE -- WIRELESS TELEGRAPHY -- ITS TRUE CHARACTER -- HOW A BOY CAN MAKE A PRACTICAL APPARATUS -- RECEIVING AND SENDING POLES -- INDUCTION-COILS, BATTERIES, COHERERS AND DE-COHERERS, ETC. -- WORKING PLANS IN DETAIL -- AËROGRAMS ACROSS THE ATLANTIC AND, PERHAPS, AROUND THE WORLD