788. As the solid land, so far as it projects out of the water, forms a horse-shoe figure, of which the two Americas represent one leg, Europe with Asia and Africa the other leg, the sea being interposed between them; so must the lines without declination fall principally in the ocean, between the earth's crura. Moreover as both these crura of the earth are unequal in size, so must the one influence the needle more than the other, and in this respect also there can be therefore no regularity in the lines without declination. Thus everything co-operates, to the effect of rendering the direction of the magnetic needle unequal; such as the distribution of metalliferous mountains, of masses of iron, of the earth's hemispheres, of the earth's crura, and inversely the earth has probably obtained this horse-shoe form through magnetism. The cavities of the earth probably do not fall in there, because the ground, namely the mountains, is supported by metallic plates. On this account the earth probably maintains an oblique position in her course. In accordance with this the earth's axis had first changed, when the metals were generated. According to this also, the sea had rushed in first, when the metallic veins were present. Lastly, in accordance with this, the metals would be generated, when the whole earth was still covered, and the veins filled with water. Unto such conclusions the philosophy of nature can alone conduct us. The cause of a horse-shoe magnet acting more powerfully than any other shaped instrument, resides probably in the form of the earth's crura.
789. The magnetic meridian varies, however, not only according to places, but times also. This is explicable from the mutation of metals under the poles, as well as under the equator and in the temperate zones. Processes of oxydation and reduction are always occurring, the more too if the water recedes and tracts of land become dry. To this, culture, the clearing of woods, the draining of swamps and probably mining operations themselves conduce.
790. It must besides be clear to every one, who has learnt to look upon nature as a whole, that the numerous metallic masses of metal upon the earth are not indifferent to the genesis of metal, that they are not foreign to iron; but that they stand invariably in one relation to it, which can only be magnetic; for therein only are they metals.
791. Magnetism is an infinity of tensions spread over the whole earth, of which the tension towards the axis is but the principal, not the sole, tension. The expression hereof is the net of metallic veins.
792. Every magnetic line consists of an endless number of shifting poles; for every magnetic line can be but the metatype of terrestrial magnetism.
Electrism.
793. Coal and sulphur may be regarded as the representatives of the Inflammables, making their appearance in the carbonic acid of lime, and the sulphuric acid of gypsum, just as the metals did among the alkalies.
794. The Inflammables are accordingly associated with the acids or the salts, the ores with the earths. It may be said that the former are reduced acids, the latter reduced earths.