An Exfraff af a Letier faiely written by an ingenicuf perjonfrom 
Paris, coniainingfome Confideraiions upan Mr, Newtons do* 
Brine of Color*, as al^o upon the effeHs if the different Refra* 
&ions of $he Rays in Tekfcoficai, Glafes^ 
I Have letnJ^owMrMtPtontndesiVoxm to maiotain his new 
Theory eooccrning Colours. Me thinks, that the rooft iai< 
portant Objeftioo, which is made agdinft hitn by way of 
re, is that, Whether there be more than two forts of Colours. 
Far my part, I believe^ that an Hypathefif^ that Ihould cii plain 
mechaoically and by the nature of motion the Colors Jellow 
and Blen>^ would be fyflScicnt for all the reft y in regard that 
thofe others, being only mor« deeply chai;gcd ( as appears by 
the Prifmcs of Mr. Hooi^) do produce the dark or deep-Red 
and Blewj and that of thefe four all the other colors may be 
compounded. Neither do I fee, why MuNemon doth not con- 
tent himleJf with th« two Colors,Yellow arid Bl€W5 for it will 
be much more eafy to fiad an Hypothefishy Motion, that may 
explicate thefe two differences, than for fo many divcrfities as 
there are of others Colors* And till he hath found this Hypo- 
thep^ he hath not taught us, wl)4tit is wherein confifts the na- 
ture and difFcreoce of CuloWSjbut only this accident (which 
certainly is veiy cocfiderable, ; of their diferent Refrangibi- 
As for the compofition of Whit^ madel)y all the Colors to- 
f ether Jt may poffifely be, that Te/Zw and S&n? might alfo be 
ftjfficitnt for that: Which is worth whik to try § and it 
may be done by the Expe rime ot^ which MrMmm propofcth, 
by receiving agiinft a wall of a darkn'd room th* Colours of 
the Prifme, and to caft their rcflefted light upon white pa^ 
per. Here you muft hinder the Colorsof the extremities, wz. 
the Red and Purple, from ftriking agatoft the wall^ atid leave 
only the intermediate Colors, yellow,green and blew, to fee, 
whether the light of thefe alone would not make the paper 
appear while,9s well as when they all give light. I even doubt, 
whether the hghteft place of the yellow color may not alLg^ 
lone producethat effea:,and I mean to try it at the firft coc- 
veniency 5 for this thought never came into my mind but juft 
BOW 
