MicROGRAPHIA. 
much in general I fhall hint,that I fippofe the medinin MMM tohave lee — 
of the tranfparent undulating fubtile matter; and that matter to belef 
implicated by it, whereas LLL I fuppofe to contain @ greater quantity 
ofthe fluid undulating fubftance,and this to bemore implicated with the 
particles of that medinm, [wo 919 amisno>. lity 
-: Butto proceed, the fame kind of obliquity of the Pulfes arid: Rays will 
happen alfo when the refraction is made out of a more eafie into. amore 
difficuile sedi ; as by the calculations of GQ & C§:R which are refracted 
from the perpendicular. In both which calculations.‘tis ebvious to.obferve, 
that always that part of the Ray: towards whichthe refraction is made 
has the end of the orbicalar pulfe. precedent tothat of the other fide, And 
always,the’oftner the refraction is made the fame way,Or the greater the 
fingle ‘refraction is;*the more is this unequal progrefs. So that baviog 
found thisodd propriety to be an infeparable concomitant of arefrade 
Ray, not ftreightned by a contrary refraction, we will next.examine the 
fefradtions of the Sun-beams, as they are fuffer'd onely to pafs througha 
{mall paflage, obliquely out of a more difficult,into amore eafie medina, 
‘Let us fuppofe therefore ABC in the fecond Figure to reprefent 
alarge Chimrical Glafi-body about two foot long, filled with very fair Wa- 
ter as high as A B, and inclin’d in a convenient pofture with B towards 
the Sun: Let us further fu thetop of it to be cover'd with an opa- 
cons j all but the hole 24, through which the Sun-beamis are fuffer'd 
to pafs into the Water,and are thereby refracted to ¢ d ¢f ,againft which 
part, if a’ Paper be expanded on the outfide, there will appear all the co- 
lours of the Rain-bow, that is, there will be generated the two principal 
colours, Scarlet and B/we, and ali the intermediate ones which arife from 
the compofition and dilutings of thefé two, that is;¢ d fhall exhibit a 
Scarlet, which toward d is diluted:into a Tel/om:s this is the reffaction of 
the Ray, 74, which comes from the underfide of the Sun ; and the Ray 
ef thall appear of adeep Blwe, which is gradually towards ¢ diluted in- 
toa pale Watchet-blue. Between d and ¢ the two diluted colours, Blue 
and Te/ow are mixt and compounded intoa Greens and this I imagineto 
be the reafon why Greex is fo acceptable a colour to the eye, and that 
either of the two extremes are, if intenfe, rather a little offenfive, riame 
ly, the being plac'd in the middle between the two extremes}, and com> 
pounded out of both thofe, diluted alfo, or fomewhat qualifi'd, forthe © 
compoftien, arifing ftom the mixture of the two extremes amdélated, — 
makes a Parple,which though it be a lovely colour,and pretty acceptable — 
to the eye, yet isit nothing comparable to the ravithing pleafure with 
which a curious and well temperéd Green affects the eye. Ifremoving 
the Paper, the eye be plac’'dagainft c d, it will perctive the lower fide 
of the Sun (or a Candle at hight which is much better, becaufe it offends 
not the eye, and is more eafily manageable) to be of adeep Red, and if — 
againtt ef it will perceive the upper part of the luminous body tobeof 
a deep B/ne ; and thefe colours will appear deeper and deeper, accord- 
ing asthe Rays from the luminous bod fall more obliquely on the fut> — 
face of the Water, and thereby fuffer a. greater refraction, and the — 
