Page:The Mathematical Principles of Natural Philosophy - 1729 - Volume 1.djvu/408

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Thee attractions bear a great reemblance to the reflexions and refractions of light, made in a given ratio of the ecants, as was dicovered by Smelluis; and conequently in a given ratio of the ines, as was exhibited by Des Cartes. For it is now certain from the phænomena of Jupiter' Satellits confirmed by the obervations of different Atronomers, that light is propagated in ucceion, and requires about even or eight minutes to travel from the Sun to the Earth. Moreover the rays of light that are in our air (as lately was dicovered by Grimaldus, by the admiion of light into a dark room through a mall hole, which I have alo tried) in their paage near the angles of bodies whether tranparent or opake (uch as the circular and rectangular edges of gold, ilver and bras coins, or of knives or broken pieces of tone or glas) are bent or inflected round thoe bodies as if they were attracted to them; and thoe rays which in their paage come nearet to the bodies are the mot inflected, as if they were mot attracted; which thing I my elf have alo carefully oberved. And thole which pas at greater ditances are les inflected; and thoe at till greater ditances are a little inflected the contrary way and form three fringes of colours. In Pl. 25. Fig. 6. repreents the edge of a knife or any kind of wedge Asb, gowog, fnunf, emtme, dlsld, are rays rays inflected towards the knife in the arcs owo, nun, mtm, lal; which inflection is greater or les according to their ditance from the knife. Now ince this inflection of the rays is performed in the air without the knife, it follows that the