Its Luigi Galvani birthday born in Italy in Bologna September 9, 1737 and died in that city Dec. 4, 1798, is a physicist and physician. Luigi Galvani is moving quickly towards studying medicine and philosophy; He is particularly interested in anatomy, taught at the University of Bologna since the eighteenth century. His doctoral thesis, De Easterners supported in 1762, focuses on the human skeleton. He rose to the rank of professor of anatomy and surgery at the University of Bologna in 1773 In 1782 he was elected professor of obstetrics at the Istituto delle Scienze. Numerous works of Galvani, who has had the greatest impact involve animal electricity. The long controversy ensued with Alessandro Volta led to the invention, by the latter, the battery Following the discovery of the Leyden jar, whose discharges cause strong muscle contractions, the question of the possible action of the electric fluid on the living body of great interest. from 1770s Galvani in turn is interested in the influence of electricity. It is therefore not surprising to find in his laboratory an electrostatic machine, Leyden jars and frogs. Observation, mentioned in his notes of 1781, eliciting surprise. While the scalpel of an assistant touches the nerve of a frog, thigh contracts violently when a spark jumps from the machine, located at a safe distance. Coincidence? Galvani, helped by his wife Lucia and his nephew Giovanni Aldini, vary the conditions of the experiment: the spark fires in remote effect muscle contraction provided that the nerve is extended by a sufficiently long lead (this phenomenon is understood at the end of the nineteenth century: the driver is an antenna for electromagnetic radiation emitted during the spark). The atmospheric electricity can it cause muscle contractions? (Galvani, De ... viribus, 1791 Plate II) The flash of lightning is a discharge of electricity the same as the spark machines, as shown by Benjamin Franklin. Can it cause the same effect as the spark of an electrical machine? wonders Galvani. A stormy day, it installs prepared frogs on the terrace. The experiment is successful: every time a flash gushed, muscles at the same time suffered many violent contractions. But a new unexpected phenomenon occurs: even in calm weather, contractions occur when the copper hook set in the spinal cord of the frog contacts the iron bars of the balcony. This seems unrelated electrical states of the atmosphere, notes Galvani. To check this, he descends into his laboratory and multiplies experiences. The leg contracts whenever nerve and muscle are connected to each other by a bow made of two different metals. It was only in 1791, when he thinks he has accumulated enough evidence to support this hypothesis, as Galvani published in Latin, the results of a decade of persistent experimentation and careful Galvani formula then the hypothesis of animal electricity, which is secreted by the brain and would discharge when nerve and muscle are connected by metal. When it reads the De viribus Alessandro Volta is already a renowned physicist. Initially skeptical, he hastens to repeat the experiments of Galvani. It ignites the discovery of Galvanis explained it as one of the finest and most surprising, and the germ of many others. But if he joins first the idea of an organic origin electricity, doubts appear quickly. In late 1792, after having experienced not only the frog but also on whole animals on his own tongue or eyes, he rejects the hypothesis of animal electricity. His experiences convinced him of the essential role of the metal arc: for him, the body tissues do not play a passive role, and is the contact of two different metals that moves electricity. This is the beginning of a war between science and galvanistes voltaïstes which soon spread throughout Europe and continues after the death of Galvani. Each experience of both a rise against the experience of others. Galvani and his supporters succeed in getting such contractions without any metal, for example by contacting the nerve with the outside of muscle and neit the era of knowledge on animal magnetism with scientientifique physicients theorist as Franz Anton Mesmer and many others. In seeking to increase the voltages produced by the contact of two different metals that Volta is brought to the shim stack zinc, silver and cardboard soaked in salt water which is its famous pier The resounding success the battery will end the controversy. It is therefore an instrument, and not a theory. It was not until some thirty years later, pioneered electrophysiology such Carlo Matteucci to restore honor assumptions Galvani on animal electricity, termed founding by the famous German physiologist Emil du Bois-Reymond . It is also the anniversary of John Henry Poynting - physicist Photo Copyleft Source : Joachim Piettre - Thinks
Posted on: Tue, 09 Sep 2014 12:27:30 +0000
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