dilata a Linear ray into a Superficialj, the CroO reffadionn of 
ihzt fecond Prifme ought by further fpiicting to dilate and draw 
that Superficial ray into a Pyramidal (olid. Butj upoo tryalj 
I found it Qthqrwife ; the Image Seiiig as regularly Obv 
long as before, and in-clia'd to both the Prifmes at ao aogle of 
45, degrees, 
I tryed alfo all other Pofitions of the fecond PrifmCj by tor- 
ning the Ends about its middle parts and in oo cafe could ob-^ 
ferve any fuch Irregularity. The Image was ever alike iocli- 
nedtoboth Prifmes, its Breadth anfwering to the Suns Dia« 
meter, and its length being greater or lefs accordingly as the 
Refraftions more or lefs agreed / or contradicted one ano* 
ther* 
And by thdfe Obfervations^ fince the Breadth of the Image 
was not augmented by theCrofs refradioo of the (econd^nim^t 
that refraftion muft have been performed without any fplitting 
or dilating of the ray 9 and therefore at leaft the Light inci- 
dent on that Prifme muft be granted aa Aggregat of Rays un^ 
equally Ttfrangible in xnY knk. And fince the Image was e- 
qually inc^io'd to both Prifmes^ and eonfequently the Refra* 
ftions alike in both, it argues^that they were performM accor- 
ding to fome Confiant Law without any irregularity. 
To determine they?^^>»iQu^- 
TQ^thQ Animadverfor ref errs to an L2tf ^"^^ 
Experiment made with two 
Wedge-like boxes ^ recited in the Micregraphjf ohhQ Ingenious 
MuHoo\ObkTV. 10, pag. 73, the defiga of which was to 
produce a// Colours out of a mixture of ^2i?<?. But there is, I 
conceive, a double defeft in this inftaoce. For, it appears 
not, that by this Experiment all colours can be produced out 
of two 3 and^ if they could^ yet the Inference would not fol- 
low* 
Th^t aJl Colours cannot by that Experiment be produced 
out of two, will appear by confideriog, that the Tinware of 
which afforded one of thofe Colou was not all over 
dfone uniform colour 5 but appear'd yelhm near the edge of 
Box,and at other places where it was thicker: affording 
all variety of colours from a/^/^ yellow to a deep- red orSc^tkil 
according to the various thicknefs of the liqadn And fo th 
1- M 11 2 lolntiQ^ 
