Isaac Bell glanced over his shoulder. He had an eerie sense that someone was watching him. But the only people he saw were Clyde’s assistants coming into the room carrying a box trailing wires. While they began attaching the wires to a disc-cutting machine, Bell went to the door and looked out. The corridor was empty, but the feeling persisted that he was under observation.

Clyde’s helpers lugged in a wooden box on top of which stood a thick round disc peppered with holes. They placed it next to the horn. “This is a carbon microphone, like you’ll find in a telephone, only much bigger. Inside this box is an electrically charged glass vacuum valve that will amplify and regenerate what the microphone hears. It is my theory that an electric recording will add an octave of sound reproduction so that we can record violins, and hopefully one day, the piano. Eventually I’ll make a microphone that lets the sound wave be lazy, unlike Edison’s microphone, which demands lots of work. By the time the sound comes out of Edison’s horn it’s exhausted, just like some poor laborer. O.K., why don’t you boys tune up while they finish hooking up wires?”

Clyde joined Bell at the door, and they stepped down the hall into a soundproof room that Clyde had built next to the recording studio. It had a window made of multiple layers of glass that looked out on the musicians. There was an enormous tin gramophone horn on a wooden box, which, Bell noticed, had wires trailing out of it and through the wall into the recording room.

He asked, “What’s this about cutting a wax disc? I thought you were putting the sound straight on film.”

“One thing at time. First I have to make a clear electrical recording. There’s no point in putting acoustically recorded sound on the film if I can’t play it back loudly enough for an audience to hear in a big theater.”

“When do you think you’ll be able to?”

“Listen to this.” Clyde closed a knife switch on the box that held the horn. The horn emitted the discordant cacophony of the musicians tuning violins and banjos. Bell listened carefully, trying to distinguish between the different instruments he was watching through the window. “I can’t hear much difference between the violin and the clarinet.”

“The fact that you’re hearing the violin at all tells me I’m on the right track.” Clyde opened the switch, and the noise stopped. “You can tell Mr. Van Dorn that we can sell a version of this microphone to Alexander Graham Bell to make longer long-distance telephone calls. Like from here all the way to New York.”

“I’ll tell him,” said Bell, adding drily, “I’ll also tell him that it sounds like we have a long way to go.”