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make White. For instance, Is Red alone be first tranfmirred to the Paperat thc place of concourie, and then the other Colours be let fall on that Red,the Question will be, whether they convert it into White by mixing wich itonly, as Bluc faliing on Yellow Light is soppofcd to compound Green, orwhether there be fönte fernher change wrought in the Colours by their Mutu-al aefing on oneanother, until, like contrary Pcripntstic Qaalitics, theybecomeailimilated. And he that lhaII explicate this last Cale Mechanically, meist con-qeiera double impoisibiiicy. He meist first Jhcw, that ntany unlilce Motionsin a Fluid can by clalhing lö aefc on one another, and change eachother, as to be-come one Uniform Motion ; and then, that an Uniform Motion can of it (elf,without any new unequal imprcllions, depart into a great variety of Motionsregularly emcqeial. And after this he rnust Further teil me, why alt Oh’ecfsappear not of thelämc Colour; that is, why their Colours in the Air, wherctbcRays that convey theilt every way arc conletledly mixt, do not aihmilatc oneanother, and become Uniform before they arrive at theSpechitor's Eye?

But if there be yet any doubting, ’tis bester to put the Event on ftirthcv Cir-cumstancesof the Experiment, thau to acquiesce in the poilibility of any Hypo-thetical Expücations. As, for instance, by trying, What will be ehe Appa-rition of thele Colours in a very quick Conleeution of one another. And thismay be eafily performed by the Rapid Gyration or a VVhcel with manySpoaksorCoggs in irs Perimeter, whole lntersticcs and Tlicknefies may be equal, andof loch a Lurgenels, that, if thc Wheel be interpoled between the Prüfnand the white concourie of thc Colours, one half of the Colours may be in-rercepted by a Spoak or tögg, and the other half pals through an lntcrstice.The Wheel being in this polfure, you may first turn it stowly abour, to lee allthe Colours fall luccclfively on the läme place of the Paper, held at their afore-fäid concourie; and if you then accelerate its Gyration, until the conleeutionof thole Colours be 1b quick, that you cannot distinguilh tlieni (everally, theresolting Colour will bea Wliitcneis pcrfcctly like that, whichan UnrefractedBeam of liglit exhibits, wlien in like manncr liicceifively interrupted by theSpoaks or Cogs of that circulating Wheel. And that this Whitenels is produ-ced by a socceilive intermixture of the Colours, without their being altiniila-ted, or reduc d to any Unitormicy, is certalnly beyond all doubt, unlels thingsthat exist not at thc läme time may notwithstanding act on one another.

There arc yet other Circumstances, by which thc truth might have beendecided; as by viewing the White Concourie of the Colours through anotherPrisin placcd clole to the eye, by whole Refraction that Whitenels may ap-pear again transformed into Colours : And then, to examine their Origin, ifan Aliillant intcrccpt any of the Colours at the Lens before their arrival at theWhitenels, thelame Colours will vanifh from amongst thole, into which thatWhitenels is converted by the fecond Prüfn. Now, if the Rays which dilip-pear bc the läme with thole that are intercepted, then it must be acknowlcdg-cd, that thc lecond Prüfn makes no new Colours in any Rays, which wercnot in them before their Concourie at the Paper. Which is a plain Indication,that the Rays oflcvcral Colours remain distinCtfrom oneanother in ehe White-nels, and that from their previous dilpositions are derived the Colours, of the

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