Many such examples might be examined, but I will take one for illustration--that of the manufacture of common salt. Let us take this manufacture as a typical one. We find in Jackson’s Antiquities and Chronology of the Chinese that, 2500 B.C., Shin-nong invented the method of obtaining salt from sea-water. He also gets credit for having composed books on medicine. In George Agricola’s De Re Metallica (1561) there is a curious set of woodcuts representing the manufacture of salt, and in the first, in which the whole process of evaporating sea-water by the sun’s rays is shown most completely from the raising of the sluices to allow the water to flow into the various evaporating ponds, to the packing of the finished salt in barrels--it is a curious fact that the trees which are introduced are _palms_, and the figure in the distance is dressed in _Oriental costume_, while even the ship seems to partake of this character. A more advanced state of things is shown in the third drawing of the 12th book, where a pan is shown, made of iron plates riveted together so as to form a flat sheet, which forms the bottom of the pan, of which the sides are composed of thick wood, strengthened with plates of iron at the corners. The bottom of the pan has a series of iron eyes or loops, and these, when it is fixed over its furnace, are attached to iron rods, which are hung from a network of wooden bars, so that the whole bottom of the pan is supported securely at a considerable number of points. The furnace is very simple, being simply a wall surrounding an oblong space, a little smaller than the pan, so that the sides of the latter may rest on the walls all round, except for a small space in front where the fuel is introduced, which apparently burns on the ground alone. The method of manufacturing salt in Japan is almost identical with that figured in Agricola. There is the same arrangement of salt garden or series of ponds and ditches, and the dirty salts mixed with sand are again lixiviated, and the filtered liquid is boiled down in curiously formed pans or boilers. Of these there are two chief forms, the first being a tank or pan formed of large pieces of slate, with the joints made with clay, and surrounded with a mud wall. The whole is covered with an arch or vault and is filled with the brine, which is then evaporated by surface heat, the fire being placed at one end and the flue at the other. The other form is very curious and interesting, and is almost identical in its principle of construction with the pan I have referred to as figured in Agricola, only in this case the materials are very different, being, instead of wood and iron, nothing more than clay or mud. It was described officially by the Japanese, in their publications at the Philadelphia Exhibition in 1876. The Japanese description of this apparatus is highly interesting. It is as follows:--