increased again: Which being, as he conceives, duly and exactly deduced,
and demonstrated, he esteems it afterwards to be easie for every one,
versed in these matters, certainly to collect and to judge, what way the
Comet, after it became invisible to the naked Eye, and could be no longer
observed with _Sextants_ and _Quadrants_, had taken, and what Line it had
described. 2, By subjecting all those Observations, with great diligence
and labour, to a rigid _Calculus_, thereby to obtain, for every day, the
_Longitudes_, _Latitudes_, _Right Ascensions, Declinations_, _Proper
motion_, _Angle_ of the _Ecliptick_ and the _AEquator_, and the _Nodes_ of
that Comet; for the construction of an _Ephemerides_ of its whole Motion.
From all which he pretends to prove, that he has not erred in his
Observation of _February_ 18, nor been prepossest by any _Hypothesis_, nor
deluded by any _Fixt Star_, as M. _Auzout_ thinketh; but that near the
_First Star_ of _Aries_ there _then_ appear'd a _Phaenomenon_, most like to
that Comet, that was seen some dayes before, if compared with the
Observations make thereof _Febr._ 12, 13, 14. Though he will not hitherto
positively determine, whether that _Phaenomenon_, which appear'd to him
_February_ 18. was {304} indeed that very Comet, which he saw with his
naked Eye, and observed with his Geometrical Instruments, the said 12, 13,
and 14. dayes of _February_; or whether it was another, and whether he had
lost that Comet, which moved towards the _Second Star_ in _Aries_: but
leaves it to the Learned World, and particularly to the _Royal Society_,
after they shall have well examined and considered all his Observations,
and the _Calculus_ raised therefrom, to judge of this, and the other
particulars in controversie.

II. _Isaacus Vossius de NILI et ALIORUM FLUMINUM ORIGINE_. It was _Numb._
14. of these _Transactions_, that gave an account of the _Cause_ of the
_Inundation of the Nile_, as it was rendred by Monsieur _de la Chambre_:
_This_ is to give you another, not only of the _Inundation_, but also of
the _Origine_ of that, and of _other Rivers_, as it is delivered by
Monsieur _Isaac Vossius_, who undertakes in this Book to shew;

1. That those _Subterraneous Channels_, through which several
_Philosophers_ teach, that the Sea discharges it self into the Rivers, are
not only imaginary, but useless, in regard 'tis impossible for the water to
rise from the Subterraneous places up to the Mountains, w