374 .Dr. Herschel on the 
its orbit ; as we fhall prefently fhew that this orbit is not in a 
fituation to permit the fatellite to luffer either eclipfes oroccul- 
tations for fome time to come. The angle vpc, therefore, if 
the arch pvq be turned towards us will be 129 0 2 / 46 // ,5 ; but, 
if direffed the contrary way, 50° 57' 13", 5- There is one cir- 
cumflance which will bring on a dilcovery of this particular, 
without waiting for eclipfes ; for if the apparent elliplis of the 
fatellite’s orbit fhould contract in a year or tw r o, we may con- 
clude this arch to lie towards the fun ; if, on the contrary, it 
opens, we (hall know that the fatellite has palled through one 
of its nodes about eight or nine years ago ; and that, therefore, 
we muff not expedt to fee it eclipfed for more than thirty 
years to come. 
Now, having already determined the pofition of the axis 
pc with refpe£t to the meridian, by adding the angles N cp and 
NcG, fig. 4. we obtain pen, 92 0 38' 29", 1 ; and having alfo 
now calculated the ambiguous angle npc, we may refolve the 
quadrantal triangle pen , in which the angle cup gives the in- 
clination of the orbit of the fatellite to the orbit of its planet, 
which will be 99 0 39' 48", 9, if the fatellite be approaching 
to its afeending node; but 8o° 20 / 1 1 // > r , if it be lately paffc 
the defeending one. 
In the fame triangle we find the fide nc , which is either 
50° 59' 0^,8 or 129 0 o' 59 // , 2 ; and taking thefe quantities, in- 
creafed by fix figns, from the longitude of the planet in its 
orbit, gives the place of the fatellite’s afeending node upon the 
orbit of the planet, either 8 s. 6° 2! 0^,3, if the preceding 
arch of the orbit pmn , be concave towards the fun ; or 
5 s. 1 8° o' 1 ",9, if it be convex. 
Thefe elements obtained, we reduce them to the ecliptic by 
refolving the triangle &nm, in which we have m&n, 46' 13" ; 
4 n& 
