ost _Southern_ Belt; by the means
whereof, he hath concluded, that _Jupiter_ turns about his _Axis_ in 9.
hours, 56. minutes, and makes 29. whole circumvolutions in 12 dayes 4.
minutes of ours, and 360 in 149. dayes. For he has found, that this _Spot_
was not caused by the Shadow of any _Satellit_, as well by reason of its
Situation, as because it appeared, when there could be no Shadow. Besides,
that its motion differed from that of the Shadows, which is almost equal,
as well towards the Edges as towards the Middle of _Jupiter_: Whereas, on
the contrary, this _Spot_ hath all the accidents, that must happen to a
thing, which is upon the surface of a round Body moving; for example, to
move much more slowly towards the Edges, than towards the Middle, and to
pass over that part, which is in the middle of the Diske, equal to the half
of the _Diameter_, in the sixth part of the time, it takes to make the
whole revolution: he having seen this half pass'd over, in 99 or 100
minutes just, as it must happen, supposing the whole circumrotation is made
in 9. hours 56. minutes.

He hath not yet been able to determine the Situation of the _Axis_, upon
which this motion is made, because the _Belts_, according to which it is
made, have for some years appeared streight, though in the precedent years,
other _Astronomers_ have seen them a little crooked: Which sheweth, that
the _Axis_ of the diurnal motion of _Jupiter_ is a little inclined to the
plain of the _Ecliptick_. But in time we may discover, what certainty there
is in this matter.

[Sidenote: _These _Tables_ are not yet sent over, but, 'tis hoped, will be,
ere long._]

After this excellent Discovery, he hath calculated many _Tables_, whereof
he gives the Explication and Use in the Letters by him addressed to the
Abbot _Falconieri_. By the means of them, one may know, _when_ this _Spot_
may be seen by us. For, having first {173} considered it in relation to the
_Sun_, in respect whereof, its motion is regular, he considers the same in
relation to the _Earth_, where _We_ observe it; and shews by the means of
his _Tables_, what is to be added or subtracted, to know, at what time the
said _Spot_ is to come into the middle of _Jupiter_'s Diske, according as
he is Oriental or Occidental. He hath also considered it in relation to an
unmovable point, which he has supposed to be the first point of _Aries_,
because we thither refer here upon Earth the beginning of all the Celestial
moti