Timeline of astronomy Rectification of Planetary Theory", eliminated the need for an equant by introducing an extra epicycle, departing from the Ptolemaic system in a way very similar to what Copernicus later also did. Ibn al-Shatir proposed a system that was only approximately geocentric, rather than exactly so, having demonstrated trigonometrically that the Earth was not the exact center of the universe. His rectification is later used in the Copernican model. Nicolaus Copernicus publishes "De revolutionibus orbium coelestium" containing his theory that Earth travels around the Sun. However, he complicates his theory by retaining Plato's perfect circular orbits of the planets. A brilliant
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