Method of Construction

HOW I MADE THIS MODEL I had a lot of trouble locating a piece of magnetite large enough to make a spoon. I also learned from people who worked with stone that magnetite is extremely difficult to work. It is all the more amazing that the Chinese were able to work with such a stone. Consequently to make this model, I decided to use sheet steel, heated and hammered to form a spoon shape. A handle was welded on and then tapered to create a balance point (many thanks to Trash Can Forge and Scott Cunningham of Hancock, NH) . It was then magnetized with a device at the Smith Physics lab. The plate and strips were cut from a sheet of brass, then the symbols were painted on the surface with nailpolish (many thanks to Xiaoching Chi). The plate was then etched in acid to make the characters stand out. The whole was assembled and sprayed with lacquer to keep the brass from tarnishing. It was difficult to achieve a sufficient magnetic strength to overcome the friction of the plate, thus the device has some limitations as a compass.

SOURCE: Needham, Joseph, Science and Civilization in China, Vol. 4, part 1:Physics, Cambridge Univ. Press, 1962.

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