“‘The light wave travels with a velocity of something over 185,000 miles a second, while the sound wave moves much slower. This difference, however, is overcome by the mechanical device in the tube-like section in the middle part of the instrument.
“‘As you have seen the sun’s rays collected and focused to one small spot by a reading glass, and the power intensified so that combustion takes place, so in a similar way does the seismaphone collect the sound waves, intensify and bring them to a focus here,’ and he indicated with his finger a point back of the metal diaphragm.
“‘By speaking into one of these instruments the sound passes through the wires, and strikes against the metal disk. This sets in motion a series of waves, which, traveling with the enormous velocity of which I have spoken, produce such rapid vibrations that the ear, unaided, cannot perceive the sound, but by means of the other half of the seismaphone these sound waves are collected and so transformed by the corresponding wires and diaphragm that the voice is reproduced by one instrument in exactly the tone spoken.
“‘By means of the seismaphones, you and I, though separated by thousands of miles, can converse as easily as though we were in the same city, connected by an ordinary metallic current.’
“In a fifteen years’ experience with patent seekers, I have met many inventive freaks, and probably something of what I was thinking of his seismaphone showed in my face, for he stopped describing it abruptly, and handing me one of the instruments, said,—
“‘I see you don’t believe a word I’ve told you, and you probably think I’m crazy; so, before I tell you anything more about the construction or possibilities of my invention, I want to ask you to take this half of the seismaphone, and go up to the top of your house. When you are ready to make the test, put the end marked “voice” to your mouth, and say in a distinct tone, “Ready, Bradley.” Then, when you see this little hammer striking against the bell, and hear a sharp tinkling inside the cylinder, put the other end to your ear and listen. Oh, you may lock me in as you go out, if you are afraid I may remove any of the bric-à-brac,’ he added, as I seemed to hesitate.
“I don’t know why it was, for I am not over credulous, but something told me the man was speaking the truth. And when you stop to think of it, what was there so very improbable about it?
“Who would have believed one hundred years ago that we would ever be able to communicate instantaneously with the inhabitants of another continent by any means whatever? Or, to come nearer to our own time, twenty years ago we would have scoffed at the idea of telegraphing without wires. Why, then, was it so impossible to transmit the tones of the human voice without them? It would be only another step in the march of progress.
“I took the instrument and climbed to the garret without a word. Placing the end he had indicated to my lips, I said loudly, ‘Ready, Bradley.’ Without any special expectation I then put the other end to my ear, and at the result nearly fell over backwards; for, as distinctly as if the man I had left down-stairs had been standing beside me, I heard him say,—
“‘Don’t speak so loud. I can hear you at this distance if you merely whisper. Now press the little button at the end marked “ear,” and wait for the megaphone attachment.’ I did as he said, and again I jumped and nearly dropped the instrument, for the room was filled with a voice which sounded louder than a peal of thunder.