( sm ) 
In the ConOderEtiCffis of my firft and 
fecond PfOpofltions, the An'madverfor Somepartiaflars YUQmmemi,d::s> 
hath rendred my Doctrine oWn-e^ml M^^^^'^^^M^-^^^'^- 
Refr^ngibllity very imperfect and raainn-' 
ed, by explicating it wholly by the Splitting of rays ; whereas IchieHy 
intended it in thofe Refractions that are performed without that fup- 
posM Irregularity fuch as the ExpermentMm Crucls rni^t have in- 
formed him of. And, in general I find, that, whilll he hath endea- 
voured to explicate my Propofitions Hypothetkally^ the more material 
fuggeftions, by which I deiignM to recommend them, have efcapM 
his confideration • fuch as are, The llnchsngeablenefs of the degree 
of Refrangibiiity peculiar to any fort of rays^ the ftrid Analogy be- 
tween the degrees of Refrangibility and Colours ^ the Difiindion 
between compounded and un-compounded colours S the Unchangea- 
blenefs of un-corapounded colours^ and the AfTertion, that if any one 
of th'e Prifraatique colours be wholly intercepted, that colour cannot 
be new produced out of the remaining Light by any further Refrac- 
tion or Reflexion whatfoever. And of what flrength ar^d efficacy 
thefe Particulars are for enforcing the Tbe&ry^ I defire therefore may 
be now confider'd, 
A-ti Accoinptof two Boo-ks» 
I. Ononis de GMerkke EXFERIMENT A NOVA MAGDEBVRGI^^ 
CA, deVACVO S FAT 10, &c: Amftelodarai A. 1672. in fol. 
Fter that the famous Author of this Book hath ra«4e a Narrative 
of the chief H)'p<?f/?^/3?/ and Opinions of both Antient and Recent 
Aftronomers concerning the Syfteme of the world, and reprefented 
the great difficulties in the and Tyehoni^^e^ and repeated 
theAnfwers to the Objedions againft the Copernicaff s he at large 
gives us his own Thoughts of the Frame and Conftitution of th« 
M-^orid • By which iVorUht underftands in this Treatife the Corapkic 
of the Planets, difpofed and orderM much after the Copemkm way , 
the Sun being feated in the midft, having his Spots about hire, 
and moving and inBuencing all the rcR: of the Planets according to 
their feverai diftances from him ^ SatPirn making the utraoil; of all 
Planets, and the End of thishis World being there, where the dif» 
fufive power and vertae of the Sun, the King and Governor of thcfo 
all^ terminates vwhich bounds-he conjedures to extend ihemfelve^ 
beyond Suturn^ to thofe Fixt Stars that are of the nearer rank co Sa-^ 
Concerning the Bodies lodged in thefe Planets, he thinks it con-- 
fonant to the Power and Wifdora of the Great Creator, that there 
Oiould be fuch a variety of them; as to flock each of the (aid Planei^t, 
■With- 
