CHAP III.
Shewing how the Earth is to be understood to be the Center.
A Center is either to be understood Geometrically or Optically, either as it is a point, or seeming a point.
If it be a point, it is conceived to be either a center of magnitude, or a center of ponderosity, or a cen∣ter of rotundity: if it be a seeming point, that is increased or diminished according to the ocular aspect, as being som∣time neerer, and somtime farther from the thing in the vi∣suall line, the thing is made more or lesse apparent.
A center of magnitude is an equal distribution from that point, an equality of distribution of the parts, giving to each end alike, and to each a like vicinity to that point or center.
A center of ponderosity is such a point in which an un∣equall thing hangs in equi libra, in an equall distribution Page 12 of the weight, though one end be longer or bigger than the other of the quantity of the ponderosity.
A center of rotundity is such a center as is the center of a Globe or Circle, being equally distant from all places.
Now the earth is to be understood to be such a center as the center of a Globe or Sphear, being equally distant from the concave superficies of the Firmament, neither is it to be understood to be a center as a point indivisible, but either comparatively or optically: comparatively in respect of the superior Orbs; Optically by reason of the far di∣stance of the one from the earth; as that the fixed Stars being far distant seeme, by the weaknesse of the sense, to be conceived as a center indivisible, when by the force and vi∣gour of reason and demonstration, they are found to ex∣ceed this Globe of earth much in magnitude; so that what our sense cannot apprehend, must be comprehended by reason: As in the Circles of the Coelestiall Orbs, because they cannot be perceived by sense, yet must necessarily be imagined to be so. Whence it is observable, that all Sun Dials, though they stand on the surface of the earth, doe as truly shew the houre as if they stood in the center.
