Since the seventeenth century, electricity and pneumatics have been connected by a particular link, a field of research where these two branches of physics joined and gave extraordinary results. This “link” is the studying of electrical discharges in rarefied gases, which produce beautifully coloured glows, “glows in the vacuum”. The analysis of these spectacular glows led to the great discoveries of the late nineteenth century, i.e. X-rays, radioactivity, and the first particle, the electron, which marked the birth of modern physics.

Here are presented some of the instruments that illustrate the development of pneumatics and electricity from the seventeenth to the twentieth century, as well as the researches on the “glows in the vacuum” and their twentieth-century revolutionary consequences.