089 ) 
moon, the Moon at G, theEartlrat c, Mars 'will he feenat y„ 
its true placets if the Earth were at T. But then, after the Full, 
the Moon at D,the Earth at d j Mars wiil be feen, not at y, but 
at s too forward :* and yet more, when the Moon ( at the laft 
Quarter ) is at E, the Earth at e, arid Mars feen at •• If there- 
fore Mars (when in oppoficion to the Sun) be found (all other 
allowances being made ) io me what too backward before the 
Full moon, and fomewhat too forward after the Full-moon., 
(and mcft of alfat the Quadratures ; ) it will be the bell con- 
firmation of the Hypothecs. ( The like may be fitted to Mars 
so other pofitions, mutatii mutandis $ and fo for the other Pla- 
nets.) 
But this proof, is of like nature as that of the Parallaxis of 
the Earths Annual Orb to prove the Copernican Hypothefis. 
If it can be obferved, it proves the Affirinative / but if it cannot' 
be obfervedfit doth not convince the Negative, but only proves 
i. shat the Semidiameter of the Earths Epicycle is fo frnall as not 
to make any difcernable Parallax. And indeed, I doubt, that 
will be the ifFue.. For the Semidiameter of this Epicycle, being 
little more than the Semidiameter of the Earth it felf, or about 
if thereof (as is conjectured, in t \\e Hypothefis > from theMag- 
s nitudes and Diftancesxif the Earth and Moon compared;) and 
i there having not as yet been obferved any difcernable Parallax 
of Mars , even in his neereft pofition to the Earth ; it is very 
fufpicious, that here it may prove fo too* And whether any of 
the other Planets will be more favourable in this point,! can- 
not fay. 
JN1MJD VERSIONS 
Of Dr. Wallis 5 upon Mr.Hobs’s fate Bo'o^ DePrincipiis Be 
Ratiocinatione Geometrarum*. 
Thefe were communicated by way of Letter 3 written in Ox- 
i /kd, July 24, 1666. to an Acquaintance of the Author^ as fob- 
lows : 
S ince I faw you laft 3 I have read over Mr. Hobs' s Book Contra 
GeometrasCpv De Prmcifriis &fatiQCinatione Geometrarum) which 
; you then fhewed me. A New Book of Old matter : Containing 
but a Repetition of what he had before told us 5 more than once • 
and which hath been Anfwered long agoe. 
In which, though there be Faults enough to offer ample mat- 
Q, q 2 ter 
