Many significant developments in the history of science and technology in China took place during the Han dynasty. The Han period saw great innovations in metallurgy. Following the inventions of the blast furnace and cupola furnace during the Zhou dynasty to make pig iron and cast iron respectively, the Han period saw the development of steel and wrought iron by use of the finery forge and puddling process. With the drilling of deep boreholes into the earth, the Chinese used not only derricks to lift brine up to the surface to be boiled into salt, but also set up bamboo-crafted pipeline transport systems which brought natural gas as fuel to the furnaces.