Thomas Edison discovers the phenomenon of thermionic…

Thomas Edison discovers the phenomenon of thermionic emission, or the Edison Effect, the basis for the electron tube, during the course of his experiments with filament material.

Although the patent describes several ways of creating the carbon filament including "cotton and linen thread, wood splints, papers coiled in various ways", it was not until several months after the patent was granted that Edison and his team discovered a carbonized bamboo filament that could last over twelve hundred hours.

The idea of using this particular raw material originated from Edison's recalling his examination of a few threads from a bamboo fishing pole while relaxing on the shore of Battle Lake in the present-day state of Wyoming, where he and other members of a scientific team had traveled so that they could clearly observe a total eclipse of the sun on July 29, 1878, from the Continental Divide.

Edison has produced a new concept: a high resistance lamp in a very high vacuum, which would burn for hundreds of hours.

While the earlier inventors had produced electric lighting in laboratory conditions, dating back to a demonstration of a glowing wire by Alessandro Volta in 1800, Edison has concentrated on commercial application, and is able to sell the concept to homes and businesses by mass-producing relatively long-lasting light bulbs and creating a complete system for the generation and distribution of electricity.

William Joseph Hammer, a consulting electrical engineer, had begun his duties as a laboratory assistant to Edison in December 1879.

He assists in experiments on the telephone, phonograph, electric railway, iron ore separator, electric lighting, and other developing inventions.

However, Hammer works primarily on the incandescent electric lamp and has been put in charge of tests and records on that device.

In 1880, he is appointed chief engineer of the Edison Lamp Works.

In his first year, the plant under General Manager Francis Robbins Upton turns out 50,000 lamps.

According to Edison, Hammer is "a pioneer of incandescent electric lighting".