This apparatus, created by the Geneva physicist Arthur Auguste De La Rive (1801-1873), who was also the Rector of the Geneva Academy, to study how the appearance of an electric spark is modified in rarefied gases with miscellaneousations in pressure and the gas used.
In the traditional version it consists of an egg-shaped glass globe with very thick walls, which is closed both at top and bottom by brass rings through which brass rods terminating with a spherical electrode penetrate. The distance between the two electrodes can be miscellaneousd by raising or lowering the upper rod, which slides through the airtight cap.
The bottom ring, which is attached to a tube with a cock, terminates on the wide circular base of the apparatus, which has a hole to receive it. The edge is perfectly flat so that it can be placed hermetically on the plate of a pneumatic machine. Once a vacuum has been created, the spark can pass between the electrodes once they have been connected to an electrostatic generator or to the terminals of a Ruhmkorff coil.
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