f H2 ) 
Means the Spe&ator will be at no Lofs to find the ex- ’ 
a£t Point where the Satellite will appear or difappear. 
And on the contrary, daring the Space of Time that 
the Earth is moving from the Oppofition through the 
fecond Quadrature to the Conjun&ion, which is from 
the Middle of March to the Beginning of October ^ 
the Eclipfes will be feen on the Eaft Side, or on the 
Left Hand of Jupiter y viewed from the Earth, and 
at the fame Diftances, as in the former Cafe, accord- 
ing as {he approaches to the Quadrature from the Op-- 
pofition,or recedes from it in going to theConjun&ion. 
By reafon of the great Diftance of the third Satellite 
from Jupiter , for about fix Weeks before and after 
the Quadratures, the Immerfions and Emerfions become 
vifible on the fame Side of the Body of Jupiter ; and 
this, without any other Proof, is an ocular Demon- 
ftration, that neither Jupiter nor any of his Sateh 
lites have any Light of their own, and none but what 
they borrow from the Sun, And the fame happens to 
the fourth Satellite , of which we have but two 
Eclipfes in the whole Year ; which, according to this 
Calculation, will happen on the ijth of January next, 
when, if the Air be clear, if will be feen to enter into 
the Shadow about Twelve at Night, on the Right Hand 
of Jupiter , at the Diftance of four Semidiameters and 
a quarter from his Center, and will emerge on the 
fame Side thirty Minutes after One in the Morning, 
at the Diftance of almoft four Semidiameters on the 
fame Side. 
After this manner will the Satellites appear, if they 
could be feen with the naked Eye:, but if they are 
feen thro* a Telefcope compofed of two Convex Glades-, 
they 
