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Pioneers of Sound


Robert Hooke


Experimental Philosopher
b. 18-7-1635 d. 3-3-1703


It is unfortunate to note that no portrait of Robert Hooke is known to exist. A possible reason for this is that he has been described as a lean, bent and ugly man and so may have never been willing to sit for a portrait. Despite his possible physical shortcomings, he made major investigations in the realms of physical science and technology.

Hooke was born on the Isle of Wright and, in his youth studied several languages such as Latin and Chinese and had a fascination for secret codes. After his education at Westminster and Christ Church in Oxford, he was elected, in January of 1665, to the post of "Curator of Experiments" for the Royal Society, and held this position for life. Later, in 1665, he secured the position of professor of geometry in Gresham Collage where he taught for 30 years.

Hooke is most famous for his experiment, which used a series of telescopes to design a "telegraphic" visual communication system, which worked over great distances. He carried out many other experiments over his lifetime. His investigation of air began with 75 questions, which provided his direction of exploration. He devised a method of supplying air to a diving bell; he constructed a double-barrelled air pump and the conical pendulum, as well as an engine for cutting clock and watch wheels. He is remembered for his invention of the anchor escarpment in clocks and spiral springs in watches. As an aid for the hard of hearing he developed the ear trumpet. He studied the number of vibrations made by a musical chord. He also conducted numerous experiments on acoustics, magnetism, metallurgy and geography, as well as the anatomy of muscles and histology of plant cells.

Hooke designed new tools and redesigned existing instruments for measuring the depth of the sea, air pressure, wind velocity, rain fall, and he constructed a superior micrometer. He deconstructed and reconstructed better forms of telescopes, burning glasses, lighting fixtures, quadrants, and pendulum systems. Hooke viewed the instruments, which he constructed, not just as extensions of our senses, but as devices which would dramatically enhance our capabilities. The improvements Hooke made to Leeuwenhoek's microscope, provides a perfect example. This instrument not only extended the range of the naked eye but also improved its ability to explore nature at the cellular level. This would in turn extend the user's reach over nature and put the investigator in a position to understand the physical world well enough to conquer it.

It is important to note that Hooke took part in the great Oxford movement, which resulted in the foundation of the Royal Society, and in fact his "Micrographia," was renowned as one of the early gems of the Society. This work coloured his discoveries on respiration, the composition of atmosphere, and the nature of light. It was in this work the word "cell" was first used.

In 1684 Robert Hooke designed a long distance visual communications system better know as the optical telegraph. 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 Turk's invasion of 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.

In 1672 Hooke attempted to prove that the Earth moved in an ellipse around the Sun and six years later proposed that the inverse square law of gravitation may explain planetary motions. Hooke wrote to Isaac Newton in 1679 asking for his opinion: - "of the compounding of the celestial motions of the planets of a direct motion by the tangent (inertial motion) and an attractive motion towards the central body". Hooke seemed unable to give a mathematical proof of his conjectures, however he claimed priority over the inverse square law and this led to a bitter dispute with Newton who, as a consequence, removed all references to Hooke from the Principia.

Hooke's connection to Faraday and Chladni.

On July 8th, 1680 Hooke conducted the experiment of glass vibrating in 6.4.8. places. This was done by putting flour on a glass plate, and bowing the edge of glass with a violin bow. The footnote to the experiment states that Hooke had observed that the motion of the glass vibrated 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 his thinking about lines of force in magnetic and electrical experiments. Hooke had varied interests and often abandoned many successful but slow moving experiments without finishing them leaving others to profit from his findings. He is probably best remembered for "Hooke's Law" relating to elasticity of a body in relation to stress.

References.
* "An Early History of the Telephone 1664-1865"
* New Universal Encyclopedia, Vol 5.
* World Book Encyclopedia, Vol 9.
* The internet



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