Circa 500 . Cast iron was produced for the first time by the Chinese during the Zhou dynasty (1046-256 .). Prior to that, it had not been possible to raise the temperature of the ore sufficiently to melt the iron and the only available iron was wrought iron created by heating iron ore in a furnace with carbon as the reducing agent and hammering the resulting spongy iron output. Furnaces of the day could reach temperatures of about 1300°C which was enough to melt copper whose melting point is 1083°C but not enough to melt iron whose melting point is 1528°C. By a combination of the addition of phosphorus to the ore which reduced its melting point, the use of a bellows to pump air through the ore to aid the exothermic reduction process and the use of improved high temperature refractory bricks forming the walls of the furnace to withstand the heat, the Chinese were able to melt the iron and cast it into functional shapes ranging from tools and pots and pans to heavy load bearing constructional members as well as fine ornamental pieces.
Grassi's arguments and conclusions were criticised in a subsequent article, Discourse on Comets ,  published under the name of one of Galileo's disciples, a Florentine lawyer named Mario Guiducci , although it had been largely written by Galileo himself.  Galileo and Guiducci offered no definitive theory of their own on the nature of comets  although they did present some tentative conjectures that are now known to be mistaken. In its opening passage, Galileo and Guiducci's Discourse gratuitously insulted the Jesuit Christopher Scheiner ,  and various uncomplimentary remarks about the professors of the Collegio Romano were scattered throughout the work.  The Jesuits were offended,  and Grassi soon replied with a polemical tract of his own, The Astronomical and Philosophical Balance ,  under the pseudonym Lothario Sarsio Sigensano,  purporting to be one of his own pupils.
In Galileo’s time, science did not have to decide between Ptolemy and Copernicus. Ptolemy’s view that all planets and the sun orbited the earth, was no longer a real option. Rather it is important, ‘that the choice now lay between Copernicus and Brahe,’ 69 because everybody believed that other planets orbited the sun. The question was, whether or not the earth was moving itself or was staying in the centre of the universe. ‘Nearly no expert believed in Ptolemaic astronomy any longer. The conflict was between Tycho Brahe and Copernicus.’ 70