66 ASTRONOMICAL OBSERVATIONS 



bright as either of them; it was hardly, vifible through 

 the reflector. 



Configuration thus, 



W 



26th, I could not find the ftar at 7I1. 11m. 



29th May, Jupiter's fecond Satellite im- h ; tt 

 merged behind the diflv - - 7.25.18,7 



1779, 2d May, an Immerfion of Jupiter's Jirjl 



Satellite into the Dijk. 



Apparent Time correct. 



h - « 



In contact . . - _ - 11.31.37,6 



Immerfion doubtful - 35. 19, 6 



certain - 35-5^6 



If the immerfions and emerfions of this nature were 

 calculated fo as to fet aftronomers to lookout for them, 

 Jupiter's fatellites might be rendered more ufeful than 

 they now are in regard to longitudes by land; and that 

 too, whether the calculations are accurate or erroneous. 



For I mean to ufe an immerfion or emerfion of any 

 kind, only to note an inftant for taking the altitude of 

 Jupiter at the place of obfervation. 



If the inftruments be of equal powers, and the eyes 

 cf equal ftrength, then certainly the altitudes will be 



taken 



