English: Chinese iron workers smelting iron ore to make pig iron and wrought iron. This illustration is only half of the picture showing the puddling process, while the right half (not shown) displays men operating a blast furnace. This illustration is an original from the Tiangong Kaiwu encyclopedia printed in 1637, written by the Ming Dynasty encyclopedist Song Yingxing (1587-1666). Picture taken on the web from http://www.uni-tuebingen.de/uni/ans/project/conference/workshop.html. The picture also appears in Figure 14-10 on page 250 of E-tu Zen Sun and Shiou-Chuan Sun's translation of the Tiangong Kaiwu encyclopedia (Pennsylvania State University Press, 1966).