_obliquely_ on the surface of the Water, and thereby suffer a greater refraction, and the more distinct, the further cdef is removed from the trajecting hole. So that upon the whole, we shall find that the reason of the _Phænomena_ seems to depend upon the _obliquity_ of the _orbicular pulse_, to the Lines of Radiation, and in particular, that the Ray cd which constitutes the _Scarlet_ has its inner parts, namely those which are next to the middle of the luminous body, precedent to the outermost which are contiguous to the dark and _unradiating_ skie. And that the Ray ef which gives a _Blue_, has its outward part, namely, that which is contiguous to the dark skie precedent to the pulse from the innermost, which borders on the bright _area_ of the luminous body. We may observe further, that the cause of the _diluting_ of the colours towards the middle, proceeds partly from the wideness of the hole through which the Rays pass, whereby the Rays from several parts of the luminous body, fall upon many of the same parts between c and f as is more manifest by the Figure: And partly also from the nature of the refraction it self, for the vividness or strength of the two terminating colours, arising chiefly as we have seen, from the very great difference that is betwixt the outsides of those _oblique undulations_ & the dark Rays circumambient, and that disparity betwixt the _approximate_ Rays, decaying gradually: the further inward toward the middle of the luminous body they are remov’d, the more must the colour approach to a white or an undisturbed light. Upon the calculation of the refraction and reflection from a Ball of Water or Glass, we have much the same _Phænomena_, namely, an _obliquity_ of the undulation in the same manner as we have found it here. Which, because it is very much to our present purpose, and affords such an _Instancia crucis_, as no one that I know has hitherto taken notice of, I shall further examine. For it does very plainly and positively distinguish, and shew, which of the two _Hypotheses_, either the _Cartesian_ or this is to be followed, by affording a generation of all the colors in the Rainbow, where according to the _Cartesian Principles_ there should be none at all generated. And secondly, by affording an instance that does more closely confine the cause of these _Phænomena_ of colours to this present _Hypothesis_.