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Otto von Guericke and his
sulfur globe (1672)
In the title of his book, Experimenta nova (ut vocantur) Magdeburgica de vacuo spatio (Amstelodami, 1672) Otto von Guericke lets us know what he considers most important: his vacuum-pump. But with this pump he did many experiments, some involving electricity and magnetism. He proved that a lodestone, or magnet, can attract iron even in a vacuum; and that electrical attraction works in a vacuum as well. Air is needed by neither magnets nor electrics. It is especially significant that air is not needed for electrical attraction. The simplest way of testing for electrica in an object is to rub it, then bring it near the fine hairs of your arm. Static electricity will move the hairs. This sensation is called "spiderweb". It is similar to the feel of a small breeze, so many early theories of electrical attraction involved air movement. William Gilbert visualized the earth as a giant magnetic globe, a terrella. He made a small terrella of lodestone, and tiny iron needles to place upon it, which demonstrated the behavior of compasses very well. Otto von Guericke wanted to discuss the Earth as an electric, so he made a sulfur globe. (Sulfur is one of the most important alchemic elements.) He rubbed it with his hands, and observed many of the phenomena we now recognize as electrostatic: attraction, repulsion, little sparks in the darkness, a crackling noise. He made a good source of static electricity; he observed; he published. But his sulfur globe left no progeny. Some scholars credit von Guericke with the first electrostatic generator; others credit Hauksbee, because his is the generator that led to today. |
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