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December 1937 Radio-Craft[Table of Contents]
People old and young enjoy waxing nostalgic about and learning some of the history of early electronics. Radio-Craft was published from 1929 through 1953. All copyrights are hereby acknowledged. See all articles from Radio-Craft.
As with the article in this month's issue of Radio-Craft magazine (December 1937), the reference to a 200th anniversary is understated by 78 years for 2015. Luigi Galvani was sort of the Benjamin Franklin of biology in that just as Franklin demonstrated that lightning was a form of electricity, Galvani showed that signals sent from the brains to the appendages of animals were electrical in nature. In my high school days in the 1970s, we duplicated his experiment by making deceased frogs' legs twitch when motivated by a D cell. Today, such an exercise would likely be met with demonstrations by animal rights people (whose lives, BTW, have probably in some way been improved as a result of previous such experiments). But, I digress. Mr. Galvani's name is now paid attribution through the many words based on it, such as galvanization, galvanometer (mechanical meter movement), galvanic corrosion (eroding of dissimilar metals), etc.
"Father of Electricity" Luigi Galvani opened for posterity a door that has swung ever wider to reveal the world, of wonders now termed, in his honor, "galvanic electricity."
Last September 9th, we celebrated the 200th anniversary of Luigi Galvani who has often been called the "Father of Electricity." We will seize this opportunity to recall the life of the great Italian scientist and research worker who gave his name to many a word used now in radio and physics, such as galvanism, galvanometer, galvano plastics, galvano surgery, galvanography, galvanic cell and others which have often resounded to the ears of all those interested in scientific questions.
Luigi Galvani was born in 1737 in Bologna. He studied medicine and became a professor in 1762. His first researches were directed towards natural history and all that concerns life's phenomena.
His studies relative to the brain constitution of birds, obtained such a great success that he decided from that time to devote himself to the study of bird physiology. However he soon realized that the subject he had chosen offered too wide a field of experiment for which he could not find sufficient time and he therefore limited his studies to the close examination of the auditory system of birds.
Frog's Legs Mark Radio-Electrical Epoch!
It was only by chance, so it seems, that he was brought, on November 6, 1780, to discover what was later named "Galvanism", which consists in producing electricity by means of a contact established between 2 substances of different nature. This experiment of his, which has become universally known as "Galvani's frog's legs experiment," marks an epoch in electrical (and radio) history.
Little indeed was known 200 years ago about electricity. All that had been transmitted to us through our ancestors was that a piece of well-polished yellow amber was known to possess the property of momentarily attracting certain light substances. Researches were actively pursued during the 17th century but they gave very poor results, until Benjamin Franklin discovered the identity of lightning and electricity and constructed the first "lightning rod." However, it was not until Galvani made his experiments that the difference between (1) static electricity produced by the mere frictional contact of 2 different substances, and (2) dynamic electricity which can be obtained chemically and is found to pervade matter and the earth, was demonstrated. Later on, Volta came and devised the cell, and then almost immediately its derivative, the battery, which made available practicable amounts of electricity.
It was sheer chance, we repeat, which brought Galvani to his discovery. One day, as a Professor of Anatomy, he was observing the contractions of a frog's legs which became animated with a sort of spasm each time a flash came out of an electric conductor placed nearby.
The contractions were, without doubt, but simple reactions. However, Galvani saw in them but the confirmation of a theory which was dear to him, mainly that they were due to the electricity (later to be called "animal electricity") contained in the animal body. From that time. he devoted himself, heart and soul, to these particular experiments.
He continued to use frogs' legs and one day. he hung some of them on the railing of his balcony. He noticed that violent reactions were produced every time he brought the frog's legs near the iron railings. The contractions were even more noticeable when he would bind the nerves or spine of the little animal to its muscles by means of a metallic wire. Galvani concluded from that, that frogs' legs could be considered as matter charged with electricity, and that the nerves and muscles of which they were constituted could be "unloaded" (discharged) like a condenser by means of the metallic wire. However, he had noticed that the contractions of the frog's legs were even more pronounced when the wire employed was made out of 2 different metals.
Alessandro Volta, Professor of Physics in Pavie (Italy), inspired himself with those experiments and found that the source of electricity was to be identified with the metal and not, like Galvani had believed, with the animal body. Following this he made important discoveries, and found among other things that 2 metallic substances of different nature when put into contact, with one another, produce opposite electricity. Yet by denying the presence of electricity in animal bodies. he made a mistake as was to be demonstrated later on.
It would take us too long to follow, step by step, these wonderful experiments. However before concluding, let us add that in later years, Oerstedt, Arago and Ampere discovered the identity of magnetic and electric currents; they succeeded in obtaining electric currents from magnetic ones, and vice versa. As a science, electricity may be said to exist only from that date. Since then it has not ceased to progress with giant strides and one may verily say that it now governs our whole existence.
Galvani's life went on afterwards in quietness and peace and there remains nothing else worth mentioning except the fact that during the Revolution, having refused to take the oath of fidelity towards the new constitution, which all officials were obliged to do, he was forced for a time to retire from his post which, however, he was not long to take up again. He died in 1798 in Bologna, Italy, which raised a monument to his memory in 1879.
Posted September 30, 2015