60 
Schems. 6. 
Fig. 3. 
: 
. 
‘not carry'd.to the eye accor. 
not fo,] cannot conceive hownit can communicate ‘its otationsor circular 
‘motion to the line ofthe Globules:between theidropand theeye: Itcan- 
onely all th 
_. And that this is true,> not:onely in one, -but-in every Ray that goes to 
the conftitution of the Primary Iris;) nay, in-every Ray, that fuffers 
two refractions, and one reflection, by the furface ofthe round body; we 
fhall prefently-fee moft-evident, if we repeat the Cartefian Schemes men- 
tioned in the tenth sedion of the eighth Chapter of his Ateteors, where 
EF K\NP. in the third Figure is one ‘of'the Rays of the Primary Iris, 
twice refracted at F and N, and once reflected: at K bythe furface of the 
Water-ball., Fors firft itis evident, that KF and KN are equal, | becaufe 
K N being the reflected part of K F they have both the fame inclination 
on the furface K that is the angles: F\K T;.and-NK V-made by:the two 
Rays.and the Tangent of K are equal;whiclris evident by the Laws of ste- 
flection’; whence it-will follow alfo;that K:N has the fame inclinationion 
the furface N, or.the Tangent of it XN thar the Ray KF has tothe fur- 
face F,orthe Tangent of it F Y; whenceit: mutt neceflarily follow,that 
the: refractions at F and N areequal; that is, KF Eand. KN P’are equal. 
‘Now, that the furface N is by the reflection anK made parallelto the fur- 
face,at, Fyis evident from the principles of reflection 3, for reflection beir 
nothing but.an inverting of the Rays;if'we re-invertthe Ray KN P, an 
make. the fame inclinations below the line.T KV thavit:has:above,:it will 
be moft evident; that K H the inyerfe of K N will be the continuation of 
‘othe line F-K,\and that L H I the inverfe ‘of O X is parallel to F'Y. And 
.HM. the inverfe of NP. is Parallel toxEF for the angle: KH 1 is-equal 
ta K\N O which is equal to K F Y, andithe:angle K H M is equal to K NP 
which is equal. toK FE which was tocbe! prov'd.«) «20 728) 
... So that: according to the:above! mentioned Cartefiam principles there 
thould be generated ‘no colour-atall ina Ball of Water orGlafs.by two 
refractions and one reflection,:which does holdimoft true indeed, if the ; 
furfaces be plain, as may be experimented with any kind of prifme where ~ 
the two refracting furfaces are equally inclin’d to the reflecting; but in — 
this the Phanomena are quite otherwife. Wi ge -galbia ts ¥d Wigho tet 
The caufe therefore of the generation of colourmuttnotbe what Des — 
Cartes afligns, namely, a.certatti ‘rotation of the Globiliethereiwhichare 
‘the particles. which<he fuppofes to\conftitute the: Re/nerd. meine, :But — 
fomewhat elfe, perhaps what we have lately fuppofed, andfhall byand — 
by further profecute and-explain.. RAMA GR ASK Ss atawulsh Bor We 
» But,Firlt I thall.craveileave to propound fome otherdifficultiesof this, 
21:3: June 
~notwithftanding exceedingly ingenious Hypothefis, which I plainly confels : 
MMW £4 Doo MN he 
to me feem fuchs .and tho are,» + BK boob. 
> Rirlt, ifthat light be» (as is,affirmed; Diopt.cap. 1. 5.8.) 
ti 2 MOD Pie 
kad A notfo pro- f 
poe motion, asan action or propenfion to motion, Ieannot conceive — 
pow ene & yd can come to be fenfible of the: verticity of a Globule, which is 
generated inaidrop of Rain; pethapsa mile off from it.For that Glabilois 
ing to his formerly recited! Principles andif 
not be by means of every ones turning the next before him ; for iff; then 
¢ Globules that are in the odd places mutt be turned rhe fame 
way 
