CROOKES TUBE WITH EVACUATION PORT, 1930's

For observing the Litho of discharge effects at different pressures. The invention of the diffusion pump by the German physicist Wolfgang Gaede in 1915, with important improvements by the American chemist Irving Langmuir, to which several different types of discharge tubes could be connected to remove the atmosphere.The most famous one is the Lenard tube, invented much earlier. (See The Cathode Ray tube site, Crookes tubes page 3)
The basic Crookes tube is a glass tube closed of at each end and an opening to evacuate the air. Two electrodes are sealed into the glass at each end, a voltage is placed across the tubes via the terminals and the air is gradually pumped out until a current is detect with amp meter. using this experiment scientist could learn the different characteristics of voltage flow in a vacuum. In 1855, Geissler invented the mercury vacuum pump thus making it possible to produce good quality vacuums in laboratory equipment.

A1382