Rays, this Power of refracting the red leſs than the orange Colour, &c. which he calls the different Refrangibility. The moſt reflexible Rays are the moſt refrangible, and from hence he evinces that the ſame Power is the Cauſe both of the Reflection and Refraction of Light.
But all theſe Wonders are merely but the Opening of his Diſcoveries. He found out the Secret to ſee the Vibrations or Fits of Light, which come and go inceſſantly, and which either tranſmit Light or reflect it according to the Denſity of the Parts they meet with. He has preſum'd to calculate the Denſity of the Particles of Air neceſſary between two Glaſſes, the one flat, the other convex on one ſide, ſet one upon the other; in order to operate ſuch a Tranſmiſſion or Reflexion, or to form ſuch and ſuch a Colour.
From all theſe Combinations he diſcovers the Proportion in which Light acts on Bodies, and Bodies act on Light.
He ſaw Light ſo perfectly, that he has determin'd to what Degree, of Perfe-
