C $10^.) 
In the CcmMcrmm^ of ray fivR m^ 
•fecond Propofitions, the Ammadverfor Som^ partidylars rccommerMio 
luih rendred my Doctririe oWn-eqtul i''''^'' co.fd.rat:on. 
RefrmgibiUty v e r y i m p e r f e c t a n d ra a i m • 
tAy by explicating it wholly by the Splitting of rays j whereas I chiefly 
intended it in thofe Refractions that are performM without that fup- 
pQsM Irregularity ^ (wch ^% tht Experimenmm Cr^f^ might have in-, 
forra'd himof. And, in general I find, that, whiill he hath endea- 
voured to explicate my Propofitions Hypothetically^ the more material 
fuggeftions, by which I defignM to recommend them, have efcapM 
his confideration • fuch as are. The llnchangeablenefs of the degree 
of Refrangibility pe;|Ctjliar to any fort of rays^ the ftrid Analogy be- 
tween the degrees of Refrangibility and Colours y ihz Diftinftion 
between compounded and un- compounded colours^ the Unchangea- 
blenefs of un- compounded colours^ and the Aflertion, that if any , one 
of the Prifmatique colours be wholly intercepted, that colour cannot 
be new produced out of the remaining Light by any further Refrac- 
tionor Reflexion whatfoever. And of what ftrength and efficacy 
thefe Particulars are for enforcing the Thsrrj^ I defire therefore may 
l>£ now confider^d. 
An Accomptof two Book'v 
h Ononis deGtfericke EXTERlMBNTA NOVA ■MAGDEBVm. 
CA. de VACVO SPATIO, ^r* Amftelodarai A. m fol. 
AFrer th^t the famous Author of this Book hath/made a Narratii,'€ 
of the chief Hypothefes and Opinions of both Antient and Recenr, 
Aftronoraers concerning the Syfteraeof the world, and reprefented 
t!l« great difficulties in the Ptdemd^^e-d^nii Tychm^^e^ and repeated 
the Anfwers to the Objeftions againft the Cofermcm ^ he at brgc 
give,sushis own Thoughts of the Frame and Gonftit-ution of tiie 
i^(?r/^-,^By which mMhc underftands. in this Treatife the Gofopkx 
of the Planets, difpofed and ordered much after the Copemicm w^K. 
the being feated in the midft, having his Spots about hifii, 
and moving and influencing all the reft of the Planets according to 
their feveral diftances from him ^ Saturn making the utmoft of all the 
Planets, and the End of this Jus World being there, where the dif^. 
fu(jve power and vertue of the Sun, the King and Governor gf thcm 
alL, terminates i which bounds he conjedures to extend ihemfelvr", 
beyond Saturn, to thofe Fixt Stars that are of the nearer rank t© i'<^- 
tHrns Orbe., 
Concerning the Bodies lodged in thefe Planets,, he thinks it con* 
fonanr to the Power and Wifdora of the Great Creator, that there 
fi'iould.be fueh a variety of iheiD j as tQ ftock^-each of the faid Planets. 
