Herschel, John

Herschel, John. Preliminary Discourse on the Study of Natural Philosophy. London Longman Green, 1830. 

The concept of a contact lens device for modifying the optical power of the eye was described by Leonardo da Vinci and later by Rene Descartes and Thomas Young. In 1823, Sir John Herschel described the appHcation of a contact lens device specifically for the purpose of correcting vision. The first contact lens was fitted to a human eye for correction of vision in 1888. The early lenses were made of blown or molded glass and were difficult to wear. 

John Dalton s Atomic hypothesis. J. Fraunhofer locates and names Fraunhofer lines A...L in solar spectrum. About the same time, Herschel discovers infrared radiation from the Sun. 

In 1822, the British astronomer Sir John Herschel observed that there was a correlation between hemihedralism and optical rotation. He found that all quartz crystals having the odd faces inclined in one direction rotated the plane of polarized light in one direction, while the enantiomorphous crystals rotate the polarized light in the opposite direction. 

Six years later Sir John Herschel 13> observed that the algebraic sign of the optical rotation of quartz crystals could be correlated with their shape, and the dextro- and levorotatory crystals look like mutual mirror images. This correlation was extended from crystals to molecules by Pasteur 14>, who postulated that the spatial arrangement of atoms in the molecules is responsible for their optical activity, and the dextro-and levorotatory molecules are in a mirror image relation. 

Robert P. Wagner and Herschel K. Mitchell, Genetics and Metabolism, John Wiley Sons, Inc., New York, N. Y., 1955. 

The author expresses his appreciation to Dudley Herschbach, Herschel Rabitz, John Coleman,... 

The author expresses his appreciation to Dudley Herschbach, Herschel Rabitz, John Coleman, and Alexander Mazziotti for their support and encouragement. The author thanks the NSF, the Henry-Camille Dreyfus Foundation, the Alfred R Sloan Foundation, and the David-Lucile Packard Foundation for their support. 

According to J. J. Thomson, Lord Rutherford s death on October 19, 1937, just on the eve of his having in the High-Tension Laboratory means of research far more powerful than those with which he had already obtained results of profound importance, is, I think, one of the greatest tragedies in the history of Science (101, 102). Lord Rutherford was the first scientist born in the overseas dominions to be buried in Westminster Abbey, beside the graves of Sir Isaac Newton, Lord Kelvin, Charles Darwin, and Sir John Herschel. 

John Frederick William Herschel, A Preliminary Discourse on the Study of Natural Philosophy [1830], facsimile edition with introduction by Michael Partridge (New York London Johnson Reprint Corporation, 1966), 305. 

When we merely note and record the phenomena which occur around us in the ordinary course of nature we are said to observe. When we change the course of nature by the intervention of our will and muscular powers, and thus produce unusual combinations and conditions of phenomena, we are said to experiment. Sir John Herschel has justly remarked that we might properly call these two modes of experience passive and active observation... [A]n experiment differs from a mere observation in the fact that we more or less influence the character of the events which we observe. 

By this time, scientists were studying light from as many sources as they could conjure. In 1822, the Scotsman David Brewster (1781-1868) invented a device that, by means of a flame, vaporized small amounts of material. The light from this vaporized material could then be smdied. He added 1,600 new spectral lines to those discovered by Fraunhofer and other investigators. During the same year, 1822, John Herschel (1792-1871), William Herschel s son, vaporized various metallic salts and established that the light from the flames could be used to detect the presence of these metals in very small samples. A few years later, William Talbot (1800-1877) showed that the spectrum of each of the chemical elements was unique and that it was possible to identify the chemical elements from their spectra. 

In 1820 Sir John Herschel, in considering the question of the different optical rotation of crystalline substances, suggested that it might be connected with an unsymmetrical form of crystallization. Later, Pasteur in 1848 while studying the salts of tartaric acid recalled this suggestion of Herschel and also a statement by Mitscherlich to the effect that the crystalline form of ordinary tartaric acid which is dextro rotatory is identical with that of racemic acid which is inactive. At that time the tw o tartaric acids just mentioned were the only ones known. 

The distances to the stars. If the stars are suns, they must be enormously further away. John Michell, the first to be quantitative about this said millions of times in 1767. At least, we would now say. William Herschel refined Michell s method to his star gauging and concluded that the disk was a kilo-light-year or so across. Firm numbers for stellar distances came only with the first measurements of parallax, almost simultaneously in 1838 by Bessel (of the functions), Struve (the middle one of a dynasty), and Henderson (working from South Africa and so able to choose Alpha Centauri for his campaign). 

In the 1820s, David Brewster (1781-1868), Sir John Herschel (1792-1871), and William Henry Fox Talbot performed similar types of experiments on the absorption of light to those by Fraunhofer. Independently, these researchers made the observation that flame spectra obtained by burning compounds of different compositions varied in systematic ways. These three researchers all produced line spectra, which they tried to relate to the dark lines observed by Fraunhofer... 

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