if he returns at two o'clock I'll see him. Go on, Professor."
"Well, to begin, may I ask you if you know what ether is?"
"Some stuff you buy at a chemist's."
"Yes, it's a volatile compound, (C2H5)2O."
"Dear me," laughed Stranleigh, "I had no idea it was that sort of thing, but now that I know all about it, continue."
"With that ether, my lord, we have nothing to do, so I need not trouble you with its chemical composition. The ether I speak of is the substance, so called for want of a better name, that fills the space between the atoms of air. It is this fluid which renders wireless telegraphy possible, for it, and not the air itself, transmits the electric impulses from the sender to the receiver. One might liken a streak of ether to a telegraph wire, insulated from other streaks of ether by infinitesimally minute particles of air. These ethereal wires seem to run, not in circles round the earth, as one might suppose, but in parallel lines, which finally impinge against the earth, or against the waves of the sea, unless they are situated at a great height, and this is the cause of Mr. Marconi's difficulty up-to-date in getting a message over more than a section of the earth's surface."
"Wait a moment. Professor; I am not sure that I follow your technical explanation, but I want first to ask you a practical question, and so reach at once
