Orrery on display in Kassel at the Astronomisch-Physikalisches Kabinett and in Dresden at the Mathematisch-Physikalischer Salon. In "De revolutionibus orbium coelestium", published in Nuremberg in 1543, Nicolaus Copernicus challenged the Western teaching of a geocentric universe in which the Sun revolved daily around the Earth. He observed that some Greek philosophers had proposed a heliocentric universe. This simplified the apparent epicyclic motions of the planets, making it feasible to represent the planets' paths as simple circles. This could be modelled by the use of gears. Tycho Brahe's improved instruments made precise observations of the skies (1576–1601), and from these Johannes Kepler
Paris in the 16th century Beginning in 1522, wealthy Parisians loaned their money to the Bureau de Ville, the city government, which in turn made loans to the King. In exchange the King gave the city the right to collect certain taxes in Paris, and the Parisian investors received a healthy eight percent return for their loans to the city. By the second part of the 16th century, however, the Kings were so deeply in debt that wealthy Parisians refused to lend any more money; the King was forced to borrow money from Italian bankers, who received the right to receive a portion of French