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| 1669 |
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| ISAAC NEWTON (1642–1727) announced his calculus, in De analysi per aequationes numero terminorum infinitas, which circulated in manuscript but was first published in 1711. He further developed the calculus in Methodus fluxionum et serierum infinitarum (1671, published 1736), using as fundamental notions “fluxions” (time derivatives) and “fluents” (inverse of fluxions), fluents being interpreted as areas. | 1 |
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| 1669 |
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| Johann Joachim Becher (1635–82) asserted that all bodies are composed of air, water, and three earths: terra lapida, terra mercurialis, and terra pinguis. In combustion the “fatty earth” (terra pinguis) burns away, and in calcination it is driven off by the action of fire. This was a forerunner of the phlogiston theory (1723), which claimed, before the discovery of oxygen, that a nonexistent chemical called phlogiston was released during combustion. | 2 |
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| 1671–73 |
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| Jean Richer (1630–96), on a scientific expedition to Cayenne (latitude 5°N), found that the intensity of gravity was less near the equator than in higher latitudes. | 3 |
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| 1672 |
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| Newton presented to the Royal Society a reflecting telescope that he constructed on principles learned in his optical studies. Newton also published his “New Theory about Light and Colors,” showing notably that white light is composed of the various spectral colors, each of which has a different index of refraction. | 4 |
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| 1673 |
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| Christiaan Huygens announced in Horologium oscillatorium the invention and theory of the pendulum clock. This work included theorems on centrifugal force in circular motion. | 5 |
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| 1675 |
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| Olaus Roemer (1644–1710), by studying the eclipses of Jupiter's moons, determined that light is transmitted with a finite though very great speed. | 6 |
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| 1676 |
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| Thomas Sydenham (1624–89) rejected the view that the diseased state is an exception to natural law. He emphasized the importance of clinical observation, experience, and common sense in therapy. | 7 |
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| 1678 |
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| Robert Hooke provided an account of the law of elastic force, ut tensio, sic vis (stress is proportional to strain), which is now known by his name. | 8 |
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| 1679 |
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| Edmé Mariotte (?1620–84) announced his discovery of the constant relation between the pressure and volume of an enclosed quantity of air (discovered independently of Robert Boyle). | 9 |
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| 1684 |
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| LEIBNIZ first published his differential calculus, based on work done independently of Newton during the period 1673–76. Leibniz based his calculus on the finding of differentials, which he understood as infinitesimal differences, and defined the integral as an infinite sum of infinitesimals; the operations of summing and of finding the differences were mutually inverse. | 10 |
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| 1686–1704 |
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| John Ray (1627–1705) in the three volumes of Historia generalis plantarum provided an able account of the structure, physiology, and distribution of plants and laid the foundations of modern systematic classification. | 11 |
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| 1687 |
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| NEWTON in his Philosophiae naturalis principia mathematica founded mechanics, both celestial and terrestrial, on his three axioms, or laws of motion. He demonstrated that the sun attracts the planets and the earth attracts the moon with a force inversely proportional to the square of the distance between them. In his principle of universal gravitation he states that any two bodies attract each other with a force proportional to the product of their masses and inversely proportional to the square of the distance between them. | 12 |
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