X 5o^ > 
'^oxf^xitwo Gmn Obje<as may to the naked eye appear oi 
the fame colour, and yet one of them throDgh a prifme feera 
and variegated with other colours ac the edges, and 
theother and entirely Greeo; or, if there may be two 
Beamsof Light, which falling on a white wall do to the na- 
ked eye exhibit the fame Gr^^w colour, and yet one of them, 
when tranfmitted through a Prifmej be uniformly and regu-^ 
4arly refra^ed^and retain its colour unchanged, and the other 
be irregularly refradied and Co divaricate into a multitude of 
other colours 5 1 fuppofc, thete two^ww/ will in both cafes be 
granted of a different Origin and conftitutioo. And if by 
mixing colours^ a ^r^^/i cannot be compounded with the pros 
ipQti\t%oi\hzVnchangeabU GreeO) I think, I may call tbat^n 
vi;/j-row^(?«»rf^icolour5 e(pecially finceits rays are alike refrau- 
giblcyand uniform in all refpects. 
^ The fame rule is to be obferv*d in examining, whether J{ed^ 
Orenge^ Tellorp^BletVj or any other colour be compounded or 
not. And, by the way, fince all White obje<as through the 
Prifme appear confus'd and terminated with coX^ms^Wbitenefs 
inuft^ according to this diftinfliion, be ever compounded, and 
that the moft of all colours^ becaufeit is the meft confus'd and 
changed by RefracSions* 
From hence I may take occafion to comm^unicate a way for 
the'improvement of MiVr(?/ir»/>f/ by Elefradion. The way is, 
%y illuminating the Objcd in a darkned room with Light of 
any convenient colour not too much compounded: for by that 
means the Microfcope will with diftin&Qcfs bear a deeper 
Charge and larger Aperture, e/pecially if its conftrudion be 
fuch, as I may hereafter defcribe ^ for, the advantage in Or- 
dinary Microfcopes will not be fo fenfible. 
Colour, or a dilBmilar Mixture of all colours ? The Experiment 
which I brought to decide itj the Ammadmrfir thinks may be 
otherwife eixplain'd, and (o concludes nothing. Buthemigh^ 
eafily have fatisfied himfelf by trying, what would be the re« ' 
•fult of a Mixture of all colours. And that very Experiment 
10. that l^hiumfs k a mixture <?/ 
. J/ Colcfirs. 
There remains now the third 
Quseretobe confider'd, which is. 
Whether WbiuntCs be an Uniform 
