rationem ob quam carbones extincti videntur nigri, <lb/> non aliam e&longs;&longs;e quàm quòd omnis eorum &longs;uperficies, <lb/> tam interna quàm externa, particulis i&longs;tis tertii ele­<lb/> menti mollioribus contecta &longs;it; quae particulae mol­<lb/>
<arrow.to.target n="marg1150"></arrow.to.target>liores cùm ignis vi à reliquis &longs;eparantur, carbones, <lb/> qui nigri erant, in cineres, non ni&longs;i ex duris & &longs;olidis <lb/> particulis conflatos atque ideò albos, mutantur; & <lb/> nulla &longs;unt corpora reflectendis radiis magis apta quàm <lb/> alba, nulla minùs quàm nigra. </s><s>Tertiò, ut putemus <lb/>
<arrow.to.target n="marg1151"></arrow.to.target>partem illam rariorem Cometae, aliâ minùs aptam e&longs;&longs;e <lb/> ad motum, & ideô, juxta leges Mechanicae, debere <lb/> &longs;emper e&longs;&longs;e in concavâ parte lineae curvae, quam <lb/> Cometa motu &longs;uo de&longs;cribit: quia &longs;ic alià paulò tar­<lb/> diùs incedit, & cùm lineae i&longs;tius cavitas &longs;emper re&longs;pi­<lb/>
<arrow.to.target n="marg1152"></arrow.to.target>ciat centrum vorticis in quo e&longs;t Cometa (ut hîc cavi­<lb/> tas ejus partis N C 2 re&longs;picit centrum S, cavitas partis <lb/> 2 3 4 re&longs;picit F &c.), ideò illum ex uno vortice in alium <lb/> tran&longs;eundo converti. </s><s>Ut videmus in &longs;agittis per ae<gap/>rem <lb/> volantibus, pennatam earum partem e&longs;&longs;e &longs;emper aliâ <lb/>
<arrow.to.target n="marg1153"></arrow.to.target>inferiorem cùm a&longs;cendunt, & &longs;uperiorem cùm de&longs;cen­<lb/> dunt. </s><s>Denique plures aliae rationes dari po&longs;&longs;ent, cur <lb/> Cometae à nobis non videantur, ni&longs;i quamdiu tran­<lb/> &longs;eunt per no&longs;trum coelum: ex minimis enim momentis <lb/> pendet, ut idem corpu radiis reflectendis aptum &longs;it <lb/>
<arrow.to.target n="marg1154"></arrow.to.target>vel ineptum: & de eju&longs;modi particularibus effectis, de <lb/> quibus &longs;atis multa experimenta non habemus, &longs;ufficere <lb/> debent veri&longs;imiles cau&longs;ae, licet eae fortè non &longs;int verae. </s></p>
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<s><margin.target id="marg1141"></margin.target>CXXXII. <lb/> Cur Cometae à nobis <lb/> non videantur, cùm <lb/> &longs;unt extra no&longs;trum <lb/> caelum: & obiter, cur <lb/> carbones &longs;int nigri, <lb/> 4& cineres albi. </s></p>
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<s>
<arrow.to.target n="marg1155"></arrow.to.target><lb/> Praeter haec autem, ob&longs;ervatur etiam circa Come­<lb/> tas, longèam radiorum veluti comam fulgere, 'a quâ <lb/>
<arrow.to.target n="marg1156"></arrow.to.target>nomen &longs;uum accepertunt; atque i&longs;tam comam &longs;emper
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