|. Whether ray which are m&mi with Dar tkular degrees 
of rcfrangibility, when they are % any means feparatedj have 
particular colours conftantly belonging to them; vit^, the leaft 
refraogiblej^y^^r/^/ ; the moK refrangiblej^/^^;? Violet 5 themid- 
d\Q,Sea-^emi and others^other colours ? And on the contrary? 
4, Whether the colour of any fort of rays apart may be 
changed by refracStion ? 
5. Whether colours by coaTefcing do really change one an- 
other to produce a new colour,or produce it by mixing only 
6, Whether a due mixture of rays, indued with all variety 
of colours^ produces Light perfecaiy like that of the Sun,and 
which hath all the fame properties^and exhibits the fame Pi'^^- 
nom ena ? 
7. Whether the component colours of each mixture be re-^ 
ally changed 5 orbeonly feparated, when from that mixture 
various colours are produced again by RefracStipn ? 
8* Whether there be any other colours produced by refra- 
dionthan inch, as ought to refult from the colours belonging 
to the diverfly refrangible rays by their' being feparated or 
mixed by thatrefraftion ? 
To determine by Experiments thefe and fuchlike ^£res 
which involve the propounded Theory, feems the moft pro- 
per and direa: way to a conclufiom And therefore I could 
v&'ilh all objeftions were fufpended, taken from Hjfothefes or 
any other heads tham thefe two 3 Of ihewing the infufficiency 
of Experiments to determine thefe V or prove any other 
parts of my Thedry, by affigning the flaws and defeats in my 
conclulioas drawn from them ; Or of producing other Ex- 
periments which direftly contradict me, if any fuch may feem 
to occur. For if the Experimerfts, which I urge, be defe^i ve, 
it cannot be difficult to fliowthe defers ; but if valid , then by 
proving the Theory they muft render all Objeaigbsinvalid. 
6* 0 far this actUrau Fropdfer s whofe Method appearing to be 
moft genuine and proper to the purpofe it is propounded for^ 
and deferviog therefoj^e to be confidered and put to trial by 
Phiiofopheri, abroad as well as at home 3 the PuWiilierjto 
iBvit:eand gratify Eorraigoers, ' was willing to deliver the a- 
boverecited Extrad of Mr* 2V"^W^';i?j' Letter in the language 
alfbofcheLearnedjas folio wethf'' Zzz^ 2 ^ Ex- 
\ 
