638 Mr. pigott’s Agronomical Obfervations 
and the firft, of courfe, who has determined its pofition 
with any degree of certainty : there is, however, reafon 
to think, that the government there will, in a fhort time, 
provide an obfervatory, and fupply the fame with pro- 
per inftraments; the firft ufe of which will, no doubt, be 
to verify the inclofed obfervations. I fpared no pains to 
render their refults as accurate as poffible. With this 
view I collected, by the help of my friends, all the ob- 
fervations of Jupiter’s fatellites I could, correfponding to 
each of ours; convinced by a mature conlideration of 
this matter, that the moft effectual method of obviating- 
the unavoidable errors which arife from the different 
goodnefs and power of inftruments from the different 
conformation of eyes, different ftates of the atmofphere 
and other circumftanccs, is to compare each obfervation 
to as great a number correfponding as poffible, made in 
different places by known obfervers, who fe longitudes 
from a given meridian are well determined, and then 
taking a mean arifing from each fuch comparifon. The 
amazing differences which not unfrequentlv are found 
in obfervations of this kind, even among aftronomers of 
high note, confirm me ftill more in this opinion ; and I 
own, I fhould prefer, in order to fettle the longitude of any 
place by Jupiter’s fatellites, three or four immerfions and 
as many emerfions, made in favourable circumftances, 
and 
