5.2 Bergman’s Research on Electricity
Of the equipment that Bergman managed to acquire as a newly promoted docent,
the most important piece was an electricity machine (Fig. 5.2), a device that would
be more than useful. Electricity was one of the hottest topics in physics at the time,
so it was probably a good career choice for a young physicist. In Bergman’s time,
only static electricity was known; the first galvanic cell, the voltaic pile, was not
invented until 1799, so a source for continuous electric current was not available. In
an electricity machine, a glass sphere or glass disc was rotated on a shaft against a
pad creating a charge separation.
Static electricity had been known for centuries and was studied by the ancient
Greeks. In 1733, French physicist Charles François de Cisternay du Fay (1698–
1739) had made a surprising discovery: static electricity could give rise not only to
attraction, but also to repulsion. There appeared to be two forms of electricity: glass
acquired one form of electricity (vitreous electricity) on rubbing, while lacquer
acquired the opposite form (resinous electricity). du Fay proposed that both forms
of electricity were present, in the same amounts, in uncharged objects. In 1745,
Ewald Georg von Kleist (1700–1748) in Kammin, Pommerania, invented the
Leyden jar, a simple capacitor which greatly simplified electrical research. In 1747,
Benjamin Franklin and Scottish physician William Watson (1715–1787) independently proposed that there was only one form of electricity and that an object could
have an excess or deficiency of electricity. Franklin was the first to use the terms
positive and negative charge. In 1750, Franklin proposed charging a Leyden jar by
sending a kite connected via a metal wire into a thunderstorm, an experiment
carried out 2 years later proving the electrical nature of lightings.
It was Klingenstierna who introduced research on electricity in Sweden. In 1740
and 1742, his student Jah. Morthensson defended two theses on electricity. Following its invention by Kleist, the Leyden jar was also described by Dutch
mathematician Professor Pieter Musschenbroek (1692–1761) in Leiden (hence the
name); whether he was an independent inventor of the Leyden jar is unknown.
Klingenstierna translated Musschenbroek’s text book, Beginsel der Naturunde
(Introduction to Natural History; 1737), to Swedish with numerous additions. In
this translation, [17] published in 1747, Klingenstierna described some electrical
experiments performed in Uppsala. The same year Strömer published a paper on
electrical phenomena, [18] and professor Pehr Elvius (1710–1749), another student
of Klingenstierna, published a paper on the history of electricity [19]. A few years
later, Strömer published a paper on the effects of electricity on the human
body [20]. After Klingenstierna gave his lecture On the Latest Discoveries in
Electricity, [21] when he concluded his term as president in the Royal Swedish
Academy of Sciences in October 1755, the electrical research in Uppsala seems to
have declined [22]. The research on electricity was, however, picked up by Klingenstierna’s and Strömer’s former student Carl Johan Wilcke in Stockholm.
5.2 Bergman’s Research on Electricity
61
Of the equipment that Bergman managed to acquire as a newly promoted docent,
the most important piece was an electricity machine (Fig. 5.2), a device that would
be more than useful. Electricity was one of the hottest topics in physics at the time,
so it was probably a good career choice for a young physicist. In Bergman’s time,
only static electricity was known; the first galvanic cell, the voltaic pile, was not
invented until 1799, so a source for continuous electric current was not available. In
an electricity machine, a glass sphere or glass disc was rotated on a shaft against a
pad creating a charge separation.
Static electricity had been known for centuries and was studied by the ancient
Greeks. In 1733, French physicist Charles François de Cisternay du Fay (1698–
1739) had made a surprising discovery: static electricity could give rise not only to
attraction, but also to repulsion. There appeared to be two forms of electricity: glass
acquired one form of electricity (vitreous electricity) on rubbing, while lacquer
acquired the opposite form (resinous electricity). du Fay proposed that both forms
of electricity were present, in the same amounts, in uncharged objects. In 1745,
Ewald Georg von Kleist (1700–1748) in Kammin, Pommerania, invented the
Leyden jar, a simple capacitor which greatly simplified electrical research. In 1747,
Benjamin Franklin and Scottish physician William Watson (1715–1787) independently proposed that there was only one form of electricity and that an object could
have an excess or deficiency of electricity. Franklin was the first to use the terms
positive and negative charge. In 1750, Franklin proposed charging a Leyden jar by
sending a kite connected via a metal wire into a thunderstorm, an experiment
carried out 2 years later proving the electrical nature of lightings.
It was Klingenstierna who introduced research on electricity in Sweden. In 1740
and 1742, his student Jah. Morthensson defended two theses on electricity. Following its invention by Kleist, the Leyden jar was also described by Dutch
mathematician Professor Pieter Musschenbroek (1692–1761) in Leiden (hence the
name); whether he was an independent inventor of the Leyden jar is unknown.
Klingenstierna translated Musschenbroek’s text book, Beginsel der Naturunde
(Introduction to Natural History; 1737), to Swedish with numerous additions. In
this translation, [17] published in 1747, Klingenstierna described some electrical
experiments performed in Uppsala. The same year Strömer published a paper on
electrical phenomena, [18] and professor Pehr Elvius (1710–1749), another student
of Klingenstierna, published a paper on the history of electricity [19]. A few years
later, Strömer published a paper on the effects of electricity on the human
body [20]. After Klingenstierna gave his lecture On the Latest Discoveries in
Electricity, [21] when he concluded his term as president in the Royal Swedish
Academy of Sciences in October 1755, the electrical research in Uppsala seems to
have declined [22]. The research on electricity was, however, picked up by Klingenstierna’s and Strömer’s former student Carl Johan Wilcke in Stockholm.
5.2 Bergman’s Research on Electricity
61