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148 Rays, this Power of refracting the red les than the orange Colour, &c. which he calls the different Refrangibility. The mot reflexible Rays are the mot refrangible, and from hence he evinces that the ame Power is the Caue both of the Reflection and Refraction of Light. all thee Wonders are merely but the Opening of his Dicoveries. He found out the Secret to ee the Vibrations or Fits of Light, which come and go inceantly, and which either tranmit Light or reflect it according to the Denity of the Parts they meet with. He has preum'd to calculate the Denity of the Particles of Air neceary between two Glaes, the one flat, the other convex on one ide, et one upon the other; in order to operate uch a Tranmiion or Reflexion, or to form uch and uch a Colour. all thee Combinations he dicovers the Proportion in which Light acts on Bodies, and Bodies act on Light.

aw Light o perfectly, that he has determin'd to what Degree, of ction