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Hooke's Connection to Oersted, Wheatstone, Faraday, and Chladni On July 8th 1680 he formed the experiment of glass vibrating 6.4.8. places. Putting flour on a glass plate, and bowing on the edge of glass did this. The foot note states that Hooke had observed that the motion of the glass was vibrating perpendicular to the surface of the glass, and that the circular figure of the flour changed into an oval one way, and the reciprocation of it changed it into an oval the other way. This phenomenon was rediscovered by Chladni in the eighteenth century, and given his name. Its importance is that it influenced Faraday in thinking about lines of force in magnetic and electrical experiments. Oersted and Wheatstone also conducted this experiment with some variations on materials. They compared notes with each other on one of Oersted's trips to England. Robert Hooke’s Telegraph System In 1684 Robert Hooke designed a long distance visual communications system better know as optical telegraphy. Hooke wrote:"tis possible to convey intelligence from any one high and eminent place, to any other that lies in sight of it and communicate one's mind at great distances". His system was not far removed from the early model created by the Greeks in 430 BC which used combinations of torches to signal letters from the alphabet from hilltop to hilltop. Hooke designed a simple wooden frame to hang symbols and letters of the alphabet. At each structure a telescope would be placed allowing the person stationed at the site to view the communications of the adjacent site. The urgency of such a system came from Hooke's concern about the year before when the Turks invaded Vienna in what we know today as "The Great Siege of Vienna". It would also be for military reasons which Claude Chappe and his brother would build the first French telegraph system for Napoleon in France over a hundred years later. Alessandro Volta and Other Early Telegraphs At the turn of the 19th century, as the Holy Roman Empire comes to an end in Italy, Alessandro Volta announces his invention of the Voltaic pile. This first form of the battery consists of a stack of alternating zinc and silver disks separated by felt soaked in brine; it is the first source of steady electric current. This new source of power is critical to the upcoming work of Joseph Henry and Michael Faraday. In 1809 Samuel Soemmering, German inventor, develops the multi-wire telegraph and in1812 Soemmering builds a telegraph that uses electrolysis for detecting electrically transmitted signals; 25 wires arrive in a tank filled with water; the ones that produce bubbles when a current is sent through them indicate the letters. It was certainly less painful then Francisco Salva’s model. In England, 1816 Sir Francis Ronalds builds an experimental single wire telegraph which is powered by a frictional electric machine in his garden at Hammersmith a young 15-year-old Sir Charles Wheatstone is a guest at the demonstration R. T. H. Laennec's Stethoscope R. T. H. Laennec invents the stethoscope in France 1816. This new technology would help in the fight against the single worst disease of the urban landscape, tuberculosis, also known as "the consumption" because the victims were almost literally consumed by it and your chances of survival were about 60%. This sickness would take both of Alexander Graham Bells brothers from him in the 1860’s. Sir Charles Wheatstone inventor of the commercial telegraph constructed a very similar device to the stethoscope in 1827 after studding the work of Savart and Wollast "On Physiology of the Ear". Wheatstone called his invention a microphone. In fact many of the key inventors who would greatly influence Phillip Reis such as, Robert Hooke, Chladni, Sir Charles Wheatstone and Herman Helmholtz studied the human ear extensively and invented similar devices at some point in their investigations of sound including Reis himself. It is possible that Wheatstone did not know about R. T. H. Laennec’s invention even though Laennec publishes his paper on the device "Traite d'Auscultation Mediate" in 1819. Ironically this was same year that Mary Wollstonecrafte Shelly of Germany publishes "Frankenstein," her romantic novel about the possible effects of science and technology. A Sidenote on Electromagnetism In 1820 Hans Christian Oersted accidentally discovers that a nearby electric current deflects a magnetized needle while conducting a public experiment in Copenhagen Denmark which was staged to prove just the opposite, that the needle would not be effected by the magnetic current or field. However the failure of this experiment sparks discussion in many scientific circles throughout Europe. On September 11th of that same year Francois Argo conducts a demonstration of electromagnetism at the Academy of Science in France. Andre Marie Ampere is a witness to this experiment and starts his own investigations, working feverishly for the next four months, and, by January of 1821, develops a mathematical theory to explain the interaction between electricity and magnetism. Ampere called this interaction "electrodynamics" He did this to differentiate "electrodynamics" from what he called "electrostatics" which was the stationary electric forces. The simple experiment was to show this interaction is found by arranging for currents to flow through two parallel wires. Andre Marie Ampere discovered that if the currents passed in the same direction the wires were attracted to each other, but if they passed in opposite directions the wires were repelled. Over the next 4 years he went on to think about more complex configurations on the theme and devised a mathematical analysis, which allowed for quantitative predictions. Continue |