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| 1833 |
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| Gauss, in Intensitas vis magnetica terrestris, presented a rigorous mathematical analysis of the earth's magnetic field and proposed a system of absolute units for the measurement of terrestrial magnetism. | 1 |
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| 1834 |
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| Adolphe Quetelet (1796–1874) initiated the London Statistical Society and later helped found several other such groups. He applied the theory of probability to the statistics of society, especially in Sur l'homme (1835). | 2 |
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| 1835 |
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| Cauchy published the first existence proof for the solution of a differential equation. | 3 |
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| 1838–39 |
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| Friedrich Bessel (1784–1846), Friedrich Struve (1793–1864), and Thomas Henderson (1798–1844) measured stellar parallax for the first time. | 4 |
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| 1842 |
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| Julius von Mayer (1814–78) stated that the total amount of energy in the universe is constant (a form of the first law of thermodynamics) and that in natural processes, energy is never lost, but only transformed from one kind to another. | 5 |
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| 1843–46 |
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| John Adams (1819–92) and Urbain LeVerrier (1811–77) independently predicted the existence of a new planet and constructed its orbit from a consideration of irregularities in the motion of Uranus. This planet, later named Neptune, was sighted in 1846 by Johann Galle (1812–1910)—a great triumph for gravitational astronomy. | 6 |
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| 1843 |
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| James Joule (1818–89) sought the connection between electricity, heat, and mechanical energy in “The Calorific Effects of Magneto-Electricity, and the Mechanical Value of Heat,” and determined by four different procedures the mechanical equivalent of heat. In 1847 he enunciated the principle of the conservation of energy. | 7 |
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| 1846 |
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| The Smithsonian Institution for the increase and diffusion of knowledge was established by the U.S. Congress, utilizing the funds bequeathed by England's James Smithson (1765–1829). | 8 |
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| 1847 |
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| Hermann Helmholtz (1821–94) announced the principle of the conservation of energy in Über die Erhaltung der Kraft. He discussed the principle in great theoretical detail and elucidated its meaning. | 9 |
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