the natural boundary, and is not, as will hereafter appear, merely a mathematical circle. It, like the earth, acquires Direction and stability toward North and South, as the earth does; also it has a circular motion toward the position of the earth, wherein it adjusts itself to its rule: it follows the ascensions and declinations of the earth's poles, and conforms exactly to the same, and by itself raises its own poles above the {42} horizon naturally according to the law of the particular country and region, or sinks below it. The loadstone derives temporary properties, and acquires its verticity from the earth, and iron is affected by the verticity of the globe even as iron is by a loadstone: Magneticks are conformable to and are regulated by the earth, and are subject to the earth in all their motions. All its movements harmonize with, and strictly wait upon, the geometry and form of the earth, as we shall afterwards prove by most conclusive experiments and diagrams; and the chief part of the visible earth is also magnetical, and has magnetick motions, although it be disfigured by corruptions and mutations without end. Why then do we not recognize this the chief homogenic substance of the earth, likest of substances to its inner nature and closest allied to its very marrow? For none of the other mixed earths suitable for agriculture, no other metalliferous veins, nor stones, nor sand, nor other fragments of the earth which have come to our view possess such constant and peculiar powers. And yet we do not assume that the whole interior of this globe of ours is composed of stones or iron (although Franciscus Maurolycus, that learned man, deems the whole of the earth's interior to consist of solid stone). For not every loadstone that we have is a stone, it being sometimes like a clod, or like clay and iron either firmly compacted together out of various materials, or of a softer composition, or by heat reduced to the metallick state; and the magnetick substance by reason of its location and of its surroundings, and of the metallick matrix itself, is distinguished, at the surface of the terrene mass, by many qualities and adventitious natures, just as in clay it is marked by certain stones and iron lodes. But we maintain that the true earth is a solid substance, homogeneous with the globe, closely coherent, endowed with a primordial and (as in the other globes of the universe) with a prepotent form; in which position it persists with a fixed verticity, and revolves with a necessary motion and an inherent tendency to turn, and it is this constitution, when true and native, and not injured or disfigured by outward defects, that the loadstone possesses above all bodies apparent to us, as if it were a more truly homogenic part taken from the earth. Accordingly native iron which _sui generis_ (as metallurgists term it), is formed when homogenic parts of the earth grow together into a metallick lode; Loadstone being formed when