icks {206} dispose magneticks and incite them, as if the orbes of
virtue were solid and material loadstones. For the magnetick force does not
pass through the whole medium or really exist as in a continuous body; so
the orbes are magnetick, and yet not real orbes nor existent by themselves.

_Diagram of motions in magnetick orbes._

[Illustration]

A B is the axis of the terrella and of the orbes, C D the aequator. On all
the orbes, as on the terrella, at the equator the versorium arranges itself
along the plane of the horizon; on the axis it everywhere looks
perpendicularly toward the centre; in the intermediate spaces E looks
toward D; and G looks toward H, not toward F, as the versorium L does on
the surface of the terrella. But as is the relation of L to F on the
surface of the terella, so is that of G to H on its orbe and of E to D on
its orbe; also all the rotations on {207} the orbes toward the termini of
the orbes are such as they are on the surface of the terrella, or toward
the termini of its surface. But if in the more remote orbes this fails
somewhat at times, it happens on account of the sluggishness of the stone,
or on account of the feebler forces due to the too great distance of the
orbes from the terrella.

_Demonstration._

Set upon the instrumental diagram described farther back [chap. 3] a plate
or stiff circle of brass or tin, on which may be described the magnetick
orbes, as in the diagram above; and in the middle let a hole be made
according to the size of the terrella, so that the plate may lie evenly on
the wood about the middle of the terrella on a meridional circle. Then let
a small versorium of the length of a barley-corn be placed on any orbe;
upon which, when it is moved to various positions on the same circle, it
will always pay regard to the dimensions of that orbe, not to those of the
stone; as is shown in the diagram of the effused magnetick forms.

While some assign occult and hidden virtues of substances, others a
property of matter, as the causes of the wonderful magnetical effects; we
have discovered the primary substantive form of globes, not from a
conjectural shadow of the truth of reasons variously controverted; but we
have laid hold of the true efficient cause, as from many other
demonstrations, so also from this most certain diagram of magnetick forces
effused by the form. Though this (the form) has not been brought under any
of our senses, and on that account is the less