Opticks Book

 [ 36 ]

that the Rays that head to the blue finish of

the Image seventy seven and that thus fuffer the greateſt Refraction within the within the, are again in the within the additional refracted than the reſt. The ſame factor I try'd alſo by belongings the Sun's light-weight into a dark area through 2 lit- tle spherical holes F and o [in Fig. 17.] made in the Window, and with 2 parallel Priſms ABC and a By placed at thoſe holes (one at each) refracting thoſe 2 beams of sunshine to the oppoſite Wall of the Chamber, in fuch man- ner that the 2 colour'd pictures P T and MN that they there painted were joined finish to finish and lay in one ſtraight Line, the red finish T of the one touching the blue finish M of the O- ther. For if theſe 2 refracted Beams were once more by a 3rd a 3rd a 3rd to the 2 firit, refracted fideways, and also the Spectrums thereby tranſlated to ſome alternative a part of the Wall of the Chamber, ſuppoſe the Spectrum atomic number 78 to atomic number 78 and also the Spectrum MN to m one, theſe tranſlated Spectrums atomic number 78 and mn wouldn't exist exist Line with their ends contiguous as before, however be broken removed from each other and become parallel, the blue finish m of the I- mage mn being by a bigger Refraction tran- flated farther from its former place MT, than the red finish t of the opposite Image atomic number 78 from the celebrity place MT; that puts the Propoſition paſt diſpute. And this happens whether or not the third Priſm DH be placed right away once the 2 once, or at a good a good them, ſo that the sunshine refracted within the 2

firſt