KEPLER, JOHN

   illustrious astronomer, born at Weil der Stadt, Würtemberg, born in poverty; studied at Tübingen chiefly mathematics and astronomy, became lecturer on these subjects at Grätz; joined Tycho Brahé at Prague as assistant, who obtained a pension of £18 for him from the Austrian government, which was never paid; removed to Lintz, where Sir Henry Wotton saw him living in a camera obscura tent doing ingenious things, photographing the heavens, "inventing toys, writing almanacs, and being ill off for cash ... an ingenious person, if there ever was one among Adam's posterity ... busy discovering the system of the world - grandest conquest ever made, or to be made," adds Carlyle, "by the sons of Adam"; he was long occupied in studying the "'motions of the star' Mars, with calculations repeated seventy times, and with the discovery of the planetary laws of the Universe"; these last are called from his discovery of them Kepler's Laws; the first, that the planets move on elliptic orbits, the sun in one of the foci; the second, that, in describing its orbit, the radius vector of a planet traverses equal areas in equal times; and the third, that the square of the time of the revolution of a planet is proportional to the cube of its mean distance from the sun; poverty pursued Kepler all his days, and he died of fever at Ratisbon (1571-1630).