circumferentiam desumi nulla ratione potest; neque ex quouis puncto sphaericè extra circumferentiam propagatur; hoc enim si fieret, ergo magnetica confusè & nulla certa lege dirigerentur, cum nulla ratio sit cur non potius ab hoc, quam illo puncto dirigantur, sed haec praeterquam quod contra Philosophiae Magneticae principia sint, experientiae quoque reclamant; certa itaque lege diriguntur, quae est ex polis CD in circumferentiam, vt ex figura apparet; non secus ac parabolica, seu elliptica speculi concauitas exceptos Solis radios ex omni puncto in punctum, qui focus dicitur, vbi & vstio fit, & ignei vigoris verum centrum reflectit, vt hinc propagati ignei radij vsibus humanis deseruiant; Non secus, dico, Magneticum vigorem ex quouis Magnetici corporis puncto, vel directè , vel reflexè in puncta polaria propagari, & hinc veluti e centris sphaericè diffundi, vbi vides partem Borealem acus SC semper circumferentiam Borealis poli C respicere, Austrina acus pate ipsi polo insistente ; partem verò acus DM Australem, circumferentiam Australis poli respicere, Borea parte poio Australi D insistente, cuius rei ratio est, quod in Magneticis, vt in Theorem. lib.1. dictum est, similes partes naturaliter se fugiant dissimiles vero se appetant.
{Ut radij in elliptica & parabolica concavitate speculi in unum punctum reflectunt, ita radij Magnetici.}
[? a point outside] the circumference cannot be selected by any means; nor is it propagated from any point spherically outside the circumference; for if this were done, then the magnetics would be confused and directed by no certain law, since there is no reason why they should not be directed from this rather than that point, but these, besides being contrary to the principles of Magnetic Philosophy, are also contradicted by experience; they are therefore directed by a certain law, which is from the poles CD to the circumference, as appears from the figure; not unlike the concavity of a parabolic or elliptical mirror, which reflects the sun's rays received from every point to the point, which is called the focus, where burning also takes place, the true center of fiery energy, so that the fiery rays propagated from here may serve human uses. It is not otherwise, I say, that the magnetic force is propagated from any point of the magnetic body, either directly or by reflection, to the polar points, and from here as if diffused from the centers spherically, where you see that the North end of the needle SC always looks back to the circumference of the North pole C, the Southern end of the needle touching that pole; and indeed the Southern part of the needle DM looks back to the circumference of the South pole, its Northern end touching the South pole D, the reason for which is that in Magnetics, as stated in Theorem. Bk. 1, similar parts naturally shun each other and opposites attract each other.
{As rays in the elliptical and parabolic concavity of a mirror bend to a single point, so do magnetic rays.}
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