(7?) 
fidered kin relation to the iS 2-572, in refpedl whereof, its motion 1$ 
regular, he confiders the lame in relation to the Earth, where We 
obierve it ; and ihews by the means of his Tables, yN\\2Lth to be ad- 
ded or fubftraCted, to know, at what time the faid Spot is to come 
into the middle oi^Jupiters Diske , according as he js Oriental or 
Occidental. He hath alfo confidered it in relation to an unmova- 
blc pointj which he has fuppofed to be the firit point of Jries, be- 
cailfe we thither refer here upon Earth the beginning of all the 
Celeftial motions, and^l'^r^ is the Primum mobile, that one would 
imagine,if we were ia Jupiter , as we do here imagine Ours of 24. 
hours. 
The Difcovery is one of the beft, that have been yet made in 
the Heavens ; and thofe^that hold the Motion of the earth,find in 
it a full Analogy. Vor,Juptter turning about the Sun, does never- 
thelefs turnabout his Axisi^ and although he be much bigger 
than the Earth, he does neverthelefs turn much more fwif tly than 
it, fince he makes more than two Turns, and a third part^ for its 
one i and carries with him 4. Moons^as the Earth does one. 
This Obfervation ought to excite all Curious perfons to endea- 
vour the perfedting of OptieJ^ oiajps, to the end that it may be difco- 
vered^whether the other Planets^as Mars,Fenus and M^r^^^ry, about 
whom no Moon hath as ygt been difcovered , do yet turn about 
their -<4;v^j-5and in how much time they do fo; efpecially M<2r/, in 
whom fomCiS/o^ is difcover*d, 2inA Venus ^ wherein M Burattini 
hath fignified from Poland^ he has obferv'd Inequalities, as in the 
Moon. 
It will be worth while, to watch for the feeing of jf^^i/^^V^r again 
this Springjthatthis happy Obfervation may be confirmed in di« 
vers places, and endeavours ufed to make new ones. 
An Account of fome Boohs, lately puhlifijed. 
I. Hydrofiatical Paradoxes^made out by ISIew Experiments ( for the - 
moftpart Fhyjic^l^ and Eafie') by the Honourable l^&bert Boyle, This 
Treatifcjpromifed in lSlumb.8. of thefe Papers,is now come forth: 
And was occalioned by the pcrufal of the Learned Monfieur Paf 
challs Tra(St, Of the ^Equilibrium of Liquors, and of the Weifbtof the 
Air: Of which two Subjects, the /^j/f/^^r having been more clearly 
made out in England by Experiments, which could not be made by 
Monfieur P^/^^W and others , that wanted the advantage of fueh 
Engines and laftrumentSj as have here been frequeatly made ufe 
A a 2 olF 5 
