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单词 Gregory, James (1638–75)
释义
Gregory, James (1638–75)

Mathematics
  • who studied in Italy before returning to hold chairs at St Andrews and Edinburgh. He obtained infinite series for certain trigonometric functions such as tan−1x, and was one of the first to appreciate the difference between convergent and divergent series. A predecessor of Newton, in 1668 he proved a simple version of the Fundamental Theorem of Calculus and knew of Taylor series 40 years before Taylor’s publication. He died at the age of 36.


Astronomy
  • His Optica promota (1663) describes the first design of telescope (the Gregorian reflector) to feature two mirrors as a means of circumventing chromatic aberration. In 1668 he described the inverse-square law for the brightness of stars, and used it to estimate the distance of Sirius by assuming Sirius and the Sun to be of comparable luminosity (his result was far smaller than the true value). His nephew, the Scottish mathematician David Gregory (1661–1708), suggested that chromatic aberration could be overcome by using a lens made of two elements of different composition; the idea, published in 1695, may have come from I. Newton.


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