Center For Integrating Research and Learning

Arrow1775 - 1799

Timelines

The Industrial Revolution, which would later spread to North America and the rest of Europe, began in Britain during this period. The movement would create a great demand for new technologies and inventions, fueling advances in science every year.

Torsion Balance

Yet in part because electricity and magnetism were not fully understood, many ideas we consider strange today continued to thrive. German physician Anton Mesmer claimed he could cure a broad range of ailments with a type of magnetic healing. (Physicians had been using electric shocks to treat patients for years.) Though his work was debunked by Benjamin Franklin and others, interest in his theories endured, giving rise in later years to hypnotism as well as other magnetic approaches to healing.

Despite the occasional charge of charlatanism, scientists continued to make great strides. Of particular note was a certain French military engineer, who in 1785 combined an ingenious invention and the use of mathematics to quantify electrification, thus proving Joseph Priestley’s assertion about the inverse-square law of electric and magnetic forces. Charles-Augustin de Coulomb’s torsion balance featured an insulating rod suspended from a wire, on either end of which was a ball. In his experiments, Coulomb would electrify one of the balls, and then give the same charge to a third ball. When he positioned this third ball close to the other electrified ball, the latter would be repelled. Coulomb could then measure the distance the repelled ball moved. In this way he worked out a formula to calculate the force between any two charges separated by a distance. The unit of this electrostatic force was named after him.

Electroscope

At about the same time, an Italian anatomy professor was experimenting with dissected frog legs (as well as human cadavers), probing a phenomenon he called “animal electricity.” Through a laboratory fluke Luigi Galvani had noticed that a metal probe touching the leg muscles of dissected frogs made the leg twitch. After disproving his first hunch that this behavior was weather related, Galvani determined it was proof of a distinct type of electric “fluid” innate to the animal. (His work would go on to inspire Mary Shelley of Frankenstein fame.)

Galvani was wrong, of course: The frog legs were not producing electricity, rather conducting it between one type of metal the legs were attached to and another in the probe. But his mistake was very fruitful, as it led to the discovery that nerves carry electrical impulses and the birth of the field of electrochemistry. It also provoked Alessandro Volta, a fellow Italian convinced that Galvani was off base, to prove him wrong. This he did most emphatically with the invention of the voltaic pile.

1775 - 1799

1775

English chemist and physicist Henry Cavendish develops the concepts of capacitance and resistance, though most of his work with electricity is not published until the late nineteenth century.

1775

Italian physicist Alessandro Volta invents a machine for generating static electricity, which he calls an electrophorus. The term also comes to be applied to the similar device created by Johannes Wilcke a decade earlier.

1777

German professor Georg Christoph Lichtenberg discovers that unusual patterns, which later come to be known as Lichtenberg figures, can be produced by electrifying fern spores or other fine powders and dusting them upon a surface that carries the opposite charge.

1778

Anton Mesmer, a German physician, establishes a magnetic healing practice based on his theories of animal magnetism in Paris after being accused of fraudulent activity in Vienna.

1781

Renowned chemist Antoine-Laurent Lavoisier of France demonstrates that the conversion of liquids or solids into gases results in electrification.

1785

French physicist Charles-Augustin de Coulomb builds a torsion balance and offers quantitative proof of the inverse square laws of electric and magnetic forces theorized by Joseph Priestley 20 years earlier.

1785

Martin Van Marum of Holland constructs a greatly improved, much more powerful electrostatic machine than had ever been built before and carries out a variety of experiments with electricity.

1787

Reverend Abraham Bennet discusses two important devices in Philosophical Transactions, one for detecting electricity (the gold leaf electroscope) and the other for amplifying a charge via induction (the electric doubler).

1791

University of Bologna anatomy professor Luigi Galvani reports his observations made over the course of 11 years on the effect of metal probes on the leg muscles of dissected frogs in the essay De Viribus Electricitatis in Motu Musculari Commentarius (“Commentary on the Effect of Electricity on Muscular Motion”). He mistakenly attributes the muscular contractions he witnesses to an innate force he dubs animal electricity.

1796

When carrying out experiments with metals placed in his mouth similar to those of Johann Sulzer, Italian physicist Alessandro Volta first believes he is experiencing the effects of animal electricity, but then finds that he can produce a current in the absence of animal tissue by utilizing a piece of cardboard moistened with brine instead of his tongue. Accordingly, he infers that the effect is incited by touching dissimilar metals to a moist object.



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