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came bordercd with Violet above, Scarlet below; but the other Semicirde 5,quite contrsry. Hcnce I make the following Inferences.

Firlb, That not only the Light Reflected from the Paper-Circle but alsofrom the ambient Air hath great Influence upon the Colourcd Image, e/pe»cially as to the Violet and Scarlet Colours. Whence perchance it will not here-after seem stränge, that the Coloured Spectrum on the Wall is so Long, butonly that the Breadth is not greater. Secondly, Werc there a more Lumi-nous Body behind the Sun, we fhould in all likelihood have the Colours osthe. Spectrum in a contrary Situation to what they appear in at prelent;Whcnce (thirdly) it seems to follow, that the presont Situation and Orderos Colours, ariseth not from any intrinsical Property os ßefrangibility,(as maintained by Mr. Newton) but from Contingent and Extrinsical Circum-stances os Neighbouring Objects. For accordingly as the Body behind thePaper-Circle was more or leis illuminated than the Circle it leis, ali the le-vcral Colours changed their Situation.

8. The next Experiment was made in Order to Mr. Newtons Doctrine osPrimary Colours, as Prop. 5. Having covered the Hole in the Window-lhutswith a thin Ilice of Iyory, the Transmitted Light appeared Yellow; but up-on adding three, four, or more Ilices, it became Red. Whence it leems tofollow, that YellowneG os Light is not a Primary Colour, butaCompoundot Red, &c.

9. The last Experiment was made in reference to Mr. Newtons rath Prop.where from his own Principies he Tenders a very Plausible Reafbn of a sur-prising Phaenomenon, related by Mr. Hookc ; namely of two Liquors, theoneJBlue, and the other Red, both leverally Transparent, yet both, is placed to-gether, became Opake. The Reason whereof, saith Mr. Newton, is, becauleis one Liquor Transmitted only Red, the other only Blue, no Rays could pa/sthro’ both.

In Reference then to this Point ; I filled two /mali Glafles with flat PolHh-cd bottoms, the one with Aqua fortis, deeply died Blue; the other with Oyl,pf Turpentine died Red ; both to that degree as to reprelent all Objects thro’them re/pectively Blue or Red. Then placing the one upon the other, Iwas able to di/cern leveral Bodies thro’ both : whereas according to Mr. Newtons Theory, no Object fhould appear thro’ both Liquors; becaule is one"Transmit only Red, the other only Blue, no Rays can pals thro' both.

P. S. fuß upon the dose of the adjoyned Letter , I received from Mr. Gasooigneyours of May the t\.th ; wherein you are qleascd to favour us with an exaEl Ac-count of the Famous Experiment of the Coloured SpeSlrum, lately exhibited beforethe Royal Society. I was much fejoyced to see the Tryats of that IlluflriouiCompany agree fi cxailly with ours here, tbo ’ in fimewhat ours disagree fromMr. Newton.

\Ansvcerti,byMr. 8. The things oppoled by Mr. Line being upon Tryals found true and grant-Newton. i bid. ed me;T begin with the New Question about the Proportion of the Lengthf. ä?8. of the Image to its 'Breadth. And it is no wonder, that Mr. Lucas found the

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