History of development of Vaxuum Tube

The 19th century saw increasing research with evacuated tubes, such as the Geissler and Crookes tubes. Scientists who experimented with such tubes included Eugen Goldstein, Nikola Tesla, Johann Wilhelm Hittorf, Thomas Edison, and many others. These tubes were mostly for specialized scientific applications, or were novelties, with the exception of the light bulb. The groundwork laid by these scientists and inventors, however, was critical to the development of vacuum tube technology.
Though the thermionic emission effect was originally reported in 1873 by Frederick Guthrie, it is Thomas Edison's 1884 investigation of the Edison Effect that is more often mentioned. Edison patented what he found, but he did not understand the underlying physics, or the potential value of the discovery. It wasn't until the early 20th century that this effect was put to use, in applications such as John Ambrose Fleming's diode used as a radio detector, and Lee De Forest's "audion" (now known as a triode) used in the first telephone amplifiers. These developments led to great improvements in telecommunications technology, particularly the first coast to coast telephone line in the US, and the birth of broadcast radio.