Robert Hooke

4 Key excerpts on "Robert Hooke"

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  The Abyss of Time

  Unraveling the Mystery of the Earth's Age

  • Claude C., Jr. Albritton(Authors)
  • 2012(Publication Date)
  • Dover Publications

    (Publisher)

  The Mr. Hook of this footnote is of course Robert Hooke, who continues to be acknowledged in footnotes wherever such diverse topics as optics, astronomy, microscopy, atomic theory, horology, thermodynamics, paleontology, botany, oceanography, geology, or navigation are detailed in an historical context. Perhaps he is most widely known for his discovery of the law of elasticity—Hooke’s Law, the proposition that deformation of elastic bodies is proportional to the force applied. Less well known are his formulations of atomic and kinetic theory. Hooke held that the properties of matter are to be understood in terms of the motions and collisions of atoms, and that what we call heat is no more than the property of a body arising from the motion or agitation of its parts. His experiments in optics contributed to the wave theory of light and further elucidated the phenomenon of diffraction.

  Hooke was not, however, concerned wholly or even mainly with theory. He was a practical man, an inventor, a “mechanick genius” in the estimation of his contemporaries. He has been credited with the invention of the universal joint, the wind gauge, the wheel barometer, a water sampler for collecting sea water at measured depths, the anchor escapement of pendulum clocks, and the balance spring for watches. Working with Robert Boyle, he built a device for evacuating air from a glass chamber, and the experiments conducted with the aid of this “pneumatic engine” demonstrated that air is necessary for combustion, for the respiration of animals, and for the transmission of sound. Through microscopes, improved according to his own design, Hooke examined a variety of artifacts and natural objects, discovering among other matters that the most pointed needle does not actually end in a point and that mites, lice, and fleas possess a peculiar beauty of their own. Examining thin slices of cork he discovered the cellular structure of plants, and named the tiny compartments “cells” because they reminded him of the clusters of small rooms occupied by monks.

  These accomplishments, and the fame that came with them, could hardly have been predicted from consideration of his childhood and early upbringing (2). Hooke was born on July 18, 1635, at the town of Freshwater on the Isle of Wight, where his father was curate of the Church of All Saints. The Reverend John Hooke, hoping that his son would also become a clergyman, served as tutor in subjects he considered appropriate to the ministry. But the son was more interested in drawing, and in making mechanical toys; by the time he was thirteen he had built from wooden parts a clock that would run, and had constructed a model ship that would fire off small guns as it sailed near shore. In 1648 the father died, and young Hooke was sent off to London with an inheritance of £100 to study art as apprentice to Peter Lely, the portraitist. But the smell of paint made the boy’s head ache, and so he left with his hundred pounds and enrolled at Westminster School, where he came under the influence of the Headmaster, Dr. Richard Busby, who was famous for his skill as a teacher. Recognizing Hooke’s unusual mental endowments, Busby coached him in studies of geometry, in other branches of mathematics, and finally in mechanics, the subject for which Hooke ever afterward showed an especial fondness. Not all of his training at Westminster was mathematical and scientific; following the classical tradition of learning, he studied Latin and Greek and acquired some competence in Hebrew. Also he studied music and learned to play the organ. Though Hooke possessed a natural vigor, his health was always delicate, and when he was about sixteen years old a growing deformity manifested itself in a crooked posture which marked him for life.

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  Physics of Continuous Matter

  Exotic and Everyday Phenomena in the Macroscopic World

  • B. Lautrup(Author)
  • 2011(Publication Date)
  • CRC Press

    (Publisher)

  8 Hooke’s law When you bend a wooden stick, the reaction grows notably stronger the further you go—until it perhaps breaks with a snap. If you release the bending force before it breaks, the stick straightens out again and you can bend it again and again without it changing its reaction or its shape. That is what we call elasticity. Robert Hooke (1635–1703). En-glish biologist, physicist, and ar-chitect (no verified contemporary portrait exists). In physics he worked on gravitation, elasticity, built telescopes, and discovered diffraction of light. His famous law of elasticity goes back to 1660. First stated in 1676 as a Latin anagram ceiiinosssttuv , he revealed it in 1678 to stand for ut tensio sic vis , meaning “as is the extension, so is the force”. In elementary mechanics the elasticity of a spring is expressed by Hooke’s law , which says that the amount a spring is stretched or compressed beyond its relaxed length is proportional to the force acting on it. In continuous elastic materials, Hooke’s law implies that strain is a linear function of stress. Some materials that we usually think of as highly elastic, for example rubber, do not obey Hooke’s law except under very small deformations. When stresses grow large, most materials deform more than predicted by Hooke’s law and in the end reach the elasticity limit where they become plastic or break. The elastic properties of continuous materials are determined by the underlying molecular level but the relation is complicated, to say the least. Luckily, there are broad classes of mate-rials that may be described by a few material parameters that can be determined empirically. The number of such parameters depends on the how complex the internal structure of the ma-terial is. We shall almost exclusively concentrate on structureless, isotropic elastic materials, described by just two material parameters: Young’s modulus and Poisson’s ratio. In this chapter, the emphasis will be on matters of principle.

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  The Mathematical Theory of Elasticity

  • Mumtaz Kassir, Richard B. Hetnarski, Józef Ignaczak(Authors)
  • 2016(Publication Date)
  • CRC Press

    (Publisher)

  The theory was concisely presented in a short sentence “Ut tensio sic vis; that is, The Power of any spring is in the same proportion with the Tension thereof.” He published this discovery at the end of his earlier Book of the Description of Helioscopes as an anagram, stated in this book in Section 3.3.1. By a “spring” Hooke did not mean a helical wire but any extensible body that returns to its original shape when the forces were removed. Although Hooke’s theory was one-dimensional, the present-day six relations between components of the stress tensor and the strain tensor are referred to as the generalized Hooke’s law. Apparently, the first to apply Hooke’s law to Galileo’s problem was Edmé Mariotte (1620–1684). Mariotte lived most of his life in Dijon, France. In 1666, he became a member of the French Academy of Sciences. He is credited with the introduction of experimental methods in France. As a result of his experiments with air, the Boyle–Mariotte law was established. Mariotte discovered Hooke’s law independently in 1680. In his work [3], he pointed out the fact that in a loaded beam, some fibers extended while other contracted. Unfortunately, he went somewhat too far in stating that half of the fibers were in each category. His contribution to the theory of elasticity came as a result of his work on the design of water pipelines for the Palace de Versailles. His experiments on wood and glass rods showed that Galileo’s theory gave values of a breaking force too large, so he developed his own theory, which included elastic properties of material. He analyzed not only cantilever beams but also beams on two supports and beams built in at both ends. ∗ The results of Mariotte’s experiments brought a few others to the field, espe- cially Gottfried Wilhelm Leibniz (1646–1716) [5] and, somewhat later, Pierre Varignon (1654–1722) [6], a French mathematician born in Caen in Normandy, a friend of Leibniz, Newton, and the members of the Bernoulli family.

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  Scientific Practices in European History, 1200-1800

  A Book of Texts

  • Peter Dear(Author)
  • 2017(Publication Date)
  • Routledge

    (Publisher)

  11 SEEING NEW THINGS

  Just as the telescope revealed hitherto unsuspected novelties on the grand scale of the heavens, so a similar optical instrument, the microscope, proved capable of revealing novelties at the level of the very small. Although the principle of the microscope had already been discussed by Galileo in 1623 in his The Assayer , it was in 1665 that the first real classic in microscopical observation appeared. Robert Hooke’s Micrographia garnered much attention for its lavish illustrations (some perhaps done by Christopher Wren), but Hooke’s work also promoted the idea that empirical research in the natural sciences could be improved by devising instruments to assist the senses in general, not only that of vision. In these views Hooke echoed Francis Bacon, who also anticipated means of improving the senses. Indeed, Hooke, who was employed by the ­Royal Society as its “curator of experiments,” responsible for trying experiments when ordered, and for entertaining the Society’s meetings with experimental demonstrations of his own, frequently invoked Bacon’s name as a guide to the right way to go about doing experimental natural philosophy.

  Source: Robert Hooke, Micrographia (London, 1665). The preface with omission of some detailed descriptions of instruments.

  The preface

  It is the great prerogative of Mankind above other Creatures, that we are not only able to behold the works of Nature, or barely to sustein our lives by them, but we have also the power of considering , comparing , altering , assisting , and improving them to various uses. And as this is the peculiar priviledge of humane Nature in general, so is it capable of being so far advanced by the helps of Art, and Experience, as to make some Men excel others in their Observations, and Deductions, almost as much as they do Beasts. By the addition of such artificial Instruments and methods , there may be, in some manner, a reparation made for the mischiefs, and imperfection, mankind has drawn upon it self, by negligence, and intemperance, and a wilful and superstitious deserting the Prescripts and Rules of Nature, whereby every man, both from a deriv’d corruption, innate and born with him,1

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