The first discovery directly connected with neon lighting technology occurred over 300 years ago. This discovery, mentioned in James Burke's Connections, happened in 1675 when Jean Picard, studying air pressure at different elevations, took one of the newly-invented mercury barometers (depicted above) up a mountain one night to measure the pressure there. He was intrigued to notice that the tube glowed faintly for some reason. Shaking the mercury caused it to glow more. This caused quite a stir in the scientific community, and soon everyone was playing with the effect.
In 1683, Otto von Guericke demonstrated that the light could also be produced by applying externally generated static electricity. This showed that electricity could be made into light, a useful idea.
The first researcher able to replicate the glow repeatably was Francis Hauksbee. He added an air valve to the barometer, and was able to demonstrate that the glow was best when the barometer was half-filled with air. He presented an explanation for the glowing mercury to the Royal Society in 1705, hypothesizing that friction between the glass and mercury was responsible. Interestingly, the phenomenon is still not completely understood. A paper published just last year discusses the effect.
Hauksbee continued his research, and the next year demonstrated a device consisting of a glass globe which could be partially evacuated and spun, whereupon pressing a hand lightly against the spinning glass resulted in the mysterious luminosity. In my opinion, this is the first real example of gas discharge illumination.
In 1734, Johann Heinrich Winkler, continuing Hauksbee's research, sealed some mercury in evacuated glass tubes and achieved a sort of portable glow light.John Rehwinkel