390

PlateXLIV.Fi g- 5*

OfL ight and Colours."

9. Suppose now the Eye placed at N ; and let N R,N Q_, be drawn parallel to L K and M K ; then ’tisplain, none of the Globules (the fame as ABCD)within the Cone R N Q_can come to the Eye at N.Thus the Globules at O and P have their refractedRays a k d and c k d including the Eye in the Cone ofObscurity : But other Globules, which lie without theCone Q_N R, as S and T, do not involve the Eye Nby the shady Cones Ik e and fk m ; and therefore someof those Rays, which are more refracted than k e or if,will fall upon the Eye, and produce a luminous circularRing or Corona, including a dark Area within, andwhose Light outwardly decreases as it is more remotefrom the Centre.

10. Much after alike Manner this great Man under-took to account for the Appearances of Mock-Suns andMock-Moons, called Parhelia and Paraselenes or Coronee ;which I shall not here detain the Reader with, because Icannot help thinking the Whole is but too much like amere (though ingenious) Hypothesis; having never ob-served in any Hail-stones any such opake Kernels, soregularly formed, and surrounded by such regular Shellsof pellucid Ice as is here supposed. However the Readerwill be agreeably entertained by perusing Mr. Hugens slearned Dissertation on this SubjeSi, printed at the End ofhis Dioptrics in his Opufcula Pojiuma.

N. B. I have let the Account of the Ablerraticn ofLight in the fixed Stars stand here, both in this and thefollowing Volume, as it was in the first Edition ; tho’the Methods of Reasoning and Demonstration by whichit is supported are such as upon a more nice Examinationare by no Means satisfactory to myself, at least I cannotreconcile them to the Notions I have cf the Nature ofVision, the Lav/s of Optics, nor the Accounts whichhave been given of Experiments made on this Subject byPersons of no small Character, who seem to be as littleinclined to take upon Credit, the Truth of this, univer-sally celebrated Doctrine ( vel jurare in Verba) as myself.(See Annot. CXII. and CXLV. Art. 19, &c.) TheArguments which render this Discovery suspected, I maytake an Opportunity one time or other to declare.

End of the Second Volume,