opticks book page 34-35

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alſo thereby abstracted, ſo that thoſe Sides ap- peared as diſtinctly outlined as did the Circum- ference of the primary Image Y. so it happens if the Glaſs of the Prilms be free from Veins, and their Sides be accurately plane and well poliſhed while not while not while not Waves or Curles that that that from Sand-holes a bit a bit sprucing with Purty. If the Glaſs be solely well poliſhed and free from Veins and therefore the Sides not accurately plane however a bit umbel-like or concavo-convex, because it oft happens; nevertheless could the 3 Spectrums Y, platinum and platinum need Penumbras, however not in equal diſtances from the Prifms. currently from this need of Pen- umbras, I knew a lot of actually that each one in all the Circles was refraéted in step with in step with regular, uniform, and conſtant law. For if there have been any irregularity within the Refraction, the correct Lines A E and GL that all the Cir- cles within the Spectrum platinum do bit, couldn't by that Refraction be tranſlated into the Lines a e and g las diſtinct and ſtraight as they were before, however there would arife in thoſe tranſlated Lines fome shadow or Crookedneſs or Un- dulation, or different different Perturbation con- trary to what's found by expertise. What- foever shadow or Perturbation fhould be created within the Circles by the croſs Refraction of the ſecond Priſm, all that shadow or Pertur- bation would be confpicuous within the right Lines a e and g one that bit bit Circles. and thus fince there's there's shadow or Perturbation in thoſe right Lines there muſt be none within the Circles. Since the diſtance between

thoſe

[ 35 ]

thoſe Tangents or breadth of the Spectrum is not increaſed by the Refractions, the Diameters of the Circles aren't aren't. Since thoſe Tangents still be right Lines, e- terribly Circle that within the within the is a lot of or Jefs refracted, is strictly within the within the tion a lot of or leſs refracted within the ſecond. And ſeeing all theſe things still still ter the ſame manner once the Rays ar once more during a during a, and once more during a fourth refract- impotence fideways, it's evident that the Rays of 1 and also the fame Circle, on their degree of Re- frangibility continue forever uniform and ho- mogeneal to at least one another, which which fe- veral Circles do dissent in degree of Refrangibi- lity, which in fome bound and conſtant pro- portion. that is that the factor i used to be to prove. there's {yet another|yet one a lot of|one more} one more 2 of this Experiment by that it becomes ſtill more plain and convincing. Let the ſecond Priſm DH [in Fig. 16.] be placed not im- mediately when the firſt, however at ſome diſtance from it ; fuppoſe within the mid-way between it and also the Wall on that the rectangular Spectrum noble metal is caft, ſo that the sunshine from the firſt Priſm could attain it within the variety of AN rectangular Spectrum seventy seven parallel to the current to the current, and be refracted fideways to create the rectangular Spectrum p t upon the Wall . And you'll notice as before, that this Spectrum noble metal is inclined thereto Spectrum P T, that the firſt Priſm forms alone while not the ſecond ; the blue ends P and p being farther diſtant from each other than the red ones T and t, and by conſequence

D 2

that

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