This clip briefly covers the vacuum tube and some of the advances in technology that happened as a result - namely, radio and broadcast television. 

Begins with footage of one of the pioneers of vacuum tube technology, Lee de Forest, who sits at a desk and writes. An animation shows how vacuum tubes work. A technician screws several tubes into a machine.

Three people read from scripts at a radio station; a microphone overhead captures their voices. The narrator tells us that radio was a result of the efficiency of vacuum tubes.

A radio jockey speaks into a mic while a person appears to fine-tune the radio’s sounds by turning several knobs.

Radio station transmission towers stand tall. The narrator says these towers began to dot the countryside as radio began to proliferate.

The narrator says that, eventually, short-wave telephone signals helped alleviate the overcrowded submarine cables - traveling by airwaves rather than by land.

And just as radio began getting popular, so did television. A father turns on the television in his living room; he then joins his wife and daughter to watch TV, enjoying the entertainment.

What appears to be a talk show is filmed at a TV station. A mic hangs over a table where several men sit and converse. In the foreground, a cameraman trains his camera on the men participating in the talk show.

In the final shot, two men sit at a table that looks like an early TV station control room.