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i. What is the Lavo according to which each Ray is more or less Refraltcd;whether it be that the fame Ray is ever Refracted according to the fame Ra-tio of the Sines of Incidence and Refraction ; and divers Rays, according todivers Ratio’s ; or that the Refraction of each Ray is greatcr or leß with-out any certain Rule ? That is, whether each Ray have a certain degree ofRefrangibility, according to which its Refraction is performed; or is Refractedwithout that Regularity ?

3 . Whether Rays, which are endued with particular degrces of Rcfrangibi*

belonging to them ; vi%. the Jealt Ketrangible, bcarlet ; the molt Ketrangible,

deep Violet ; the middle, Sea-Green; and others, other Colours? And on thecontrary ?

4. Whether the Colour of any fort of Rays apart may be changcd byRefraction ?

5. Whether Colours by coalcseing do really C bange one another to producea Ist» Colour, or produce it by Mixing only ?

6. Whether a duc Mixture of Rays, indued with allvariety of Colours, pro-duces Light pcrfectly libe that of the Sun , and which hathall the fame proper-ties, and exhibits the fame Ph«nomena?

7. Whether the Component Colours of each mixture be really Changcd \ orbe* only Scparated, when from that Mixture various Colours are produced a-gain by Refraction ?

8. Whether there beany other Colours produced by RcfraElion than such, asought to resuit from the Colours belonging to the diverfly Refrangible Rays , bytheir being scparated or mixed by that Refraktion ?

To determine by Experiments these and such like Queries, which involvethe propounded Theory, feems the most proper and direct way to a Con-citi hon. And therefore I could wifli all Objections were sulpended, takcnfrom Hypothese* or any other heads than these two ; Of Ihewing the Insusti-ciency of Experiments to determine these Queries, orproveany other parts ofmy Theory, by alligning the flaws and defects in my Conclusions drawnfrom them ; or of producing other Experiments which directly contra-dict me, if any such may lcem to occur. For if the Experiments, which Iurge, be Defective, it cannot be difficult to fhcw the Defects • but if Valid,then by proving the Theory they must render all Objections Invalid.

IV. i. Istaec tam extraordinaria Hypothesis, quae Dioptrie« fundamenta evertit,praxesque hactenus institutas inutiles reddit, tota nititur illo Experimento Pris- «?°»ibis Tbeo-matis Crystallini, ubi Radij per foramen fenestrae intra obscurum Cubi- p ^ ^Gastonculum jngreiTi, ac deinde in Parietem impacti, aut in charta recepti, non in Pardies. n. 84.rotundum conformati, ut Cl.Newteno, ad Regulas Refractionum receptas at- 4287.tendenti, expectandum videbatur, sed in Oblongam 6guram extensi apparu-erunt : Unde conclusit. Oblongam ejusmodi figuram ex eo este, quod nonnulliRadij minus, nonnulli magis Refringerentur.

Sed mihi quidem videtur juxta communes & receptas Dioptrie« Leges figu-ram illam, non Rotundam, sed Oblongam este oportere. Cum enim Radii

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