(8o8) 
which exhaleth from the Sun and the other Planets, not onely if- 
fues out of them in a ftraight way> butalfo, whirfl thofe Bodies, 
together with their Atmofphere., move round, turnes confhntly 
about with them, till it deferc the faid Atmofphere. To which 
he adds, that the matter of thofe exhalations are of the like 
nature with our Terreftrial Vapors, in that they are apt to con- 
denfe, and after a while to be diflblved, and to return ag:iin to 
their firft principles. Having fuppofed this, heaffumes farther, 
that Bodies turnM round, the longer they move, and the greater 
the Circle is, they move in, the greater impetus and^ehemence 
they acquire, tending alwayes to recede from the Center to the- 
Circumference., and being feparated andfet at liberty from their 
vertiginous or circular motion, they continue to be moved ( as. 
long as no flop intervenes, ) but no more in that circular], but 
in a (Iraight line, viz. in the Tangent of the Circle. 
After this manner he concludeth, That as foon as vapors ex- 
hale or are expelled out of a Celeftial Body, whether it bt the: 
Sun or other Planets , into the Atmofphere incompaflrng- it" 
(which that they do., he endeavours to prove) they ftrll acquire 
more and more force to move from the Center or the Planet to 
the Circumference ( by vertue of the fwift circumrotation of 
the Atmofphere, which together with its Body or Planet is turnd 
round about,) till at laft, being eje&ed out of their Circle into 
the free Sky, and more and more fupplyed with the accefljon of 
she like matter, they make up the Bodies of Comets, ancfthtn* 
move in aftraight line, ob verting onefide to the Sun, as Clouds 
do theirs to our Earth. 
Having laid down this, hededuceth thence the explication of 
the fhanomem^ and Queftions, hitherto obftrvedand raifed in 
and about Comets, viz. How they increafc; in bulk, and com- 
monly with much quicknefs near the Sun? Why they aremade 
up of feveral Kernels ? Why not all Comet ick -.matter is. moved 
towards the fame quarter of the Heavens I How It comes to 
pafs, chat at one and the fame time more Comets than one are 
produced, and that they meet one another, and by their mutu- 
al cencourfe change one anothers motion -, or break into par s 
and focenftitute feveral Stars < Why all Comets are not "tifible. 
to use' Why there are more Comets in one Age, -than another? 
