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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Benjamin Franklin | 10/18 | https://en.wikipedia.org/wiki/Benjamin_Franklin | reference | science, encyclopedia | 2026-05-05T06:45:43.564691+00:00 | kb-cron |
Franklin was, along with his contemporary Leonhard Euler, the only major scientist who supported Christiaan Huygens's wave theory of light, which was basically ignored by the rest of the scientific community. In the 18th century, Isaac Newton's corpuscular theory was held to be true; it took Thomas Young's well-known slit experiment in 1803 to persuade most scientists to believe Huygens's theory. Franklin started exploring the phenomenon of electricity in the 1740s, after he met the itinerant lecturer Archibald Spencer, who used static electricity in his demonstrations. He proposed that "vitreous" and "resinous" electricity were not different types of "electrical fluid" (as electricity was called then), but the same "fluid" under different pressures. (The same proposal was made independently that same year by William Watson.) He was the first to label them as positive and negative respectively, which replaced the then current distinction made between 'vitreous' and 'resinous' electricity, and he was the first to discover the principle of conservation of charge. In 1748, he constructed a multiple plate capacitor, that he called an "electrical battery" (not a true battery like Volta's pile) by placing eleven panes of glass sandwiched between lead plates, suspended with silk cords and connected by wires. In pursuit of more pragmatic uses for electricity, remarking in spring 1749 that he felt "chagrin'd a little" that his experiments had heretofore resulted in "Nothing in this Way of Use to Mankind", Franklin planned a practical demonstration. He proposed a dinner party where a turkey was to be killed via electric shock and roasted on an electrical spit. After having prepared several turkeys this way, he noted that "the birds kill'd in this manner eat uncommonly tender." Franklin recounted that in the process of one of these experiments, he was shocked by a pair of Leyden jars, resulting in numbness in his arms that persisted for one evening, noting "I am Ashamed to have been Guilty of so Notorious a Blunder." Franklin briefly investigated electrotherapy, including the use of the electric bath. This work led to the field becoming widely known. In recognition of his work with electricity, he received the Royal Society's Copley Medal in 1753, and in 1756, he became one of the few 18th-century Americans elected a fellow of the Society. The CGS unit of electric charge has been named after him: one franklin (Fr) is equal to one statcoulomb. Franklin advised Harvard University in its acquisition of new electrical laboratory apparatus after the complete loss of its original collection, in a fire that destroyed the original Harvard Hall in 1764. The collection he assembled later became part of the Harvard Collection of Historical Scientific Instruments, now on public display in its Science Center.
==== Kite experiment and lightning rod ====
Franklin published a proposal for an experiment to prove that lightning is electricity by flying a kite in a storm. On May 10, 1752, Thomas-François Dalibard of France conducted Franklin's experiment using a 40-foot-tall (12 m) iron rod instead of a kite, and he extracted electrical sparks from a cloud. On June 15, 1752, Franklin may possibly have conducted his well-known kite experiment in Philadelphia, successfully extracting sparks from a cloud. He described the experiment in his newspaper, The Pennsylvania Gazette, on October 19, 1752, without mentioning that he himself had performed it. This account was read to the Royal Society on December 21 and printed as such in the Philosophical Transactions. Joseph Priestley published an account with additional details in his 1767 History and Present Status of Electricity. Franklin was careful to stand on an insulator, keeping dry under a roof to avoid the danger of electric shock. Others, such as Georg Wilhelm Richmann in Russia, were indeed electrocuted in performing lightning experiments during the months immediately following his experiment. In his writings, Franklin indicates that he was aware of the dangers and offered alternative ways to demonstrate that lightning was electrical, as shown by his use of the concept of electrical ground. He did not perform this experiment in the way that is often pictured in popular literature, flying the kite and waiting to be struck by lightning, as it would have been dangerous. Instead he used the kite to collect some electric charge from a storm cloud, showing that lightning was electrical. On October 19, 1752, in a letter to England with directions for repeating the experiment, he wrote: