$g ASTRONOMICAL OBSERVATIONS 



O On the meridian, June 18, 23.51.47,75 n °w 8.12,25 



^4?i Immerfton of Jupiter's Jirjl Satellite. 



The Planet was extremely bright, and the Belts dif- 

 linct and clear; the glafs perfectly fteady h /y 

 19th June, by watch changed colour 15.16.22 



Immerged 15.18.38 

 Too flow at moon 4- 8.12,25 

 Lofs to obfervation at 219+ 2.21 



Immerfion 15,29.11,15 

 Ephemeris 10.00.13 



Longitude in time 5.28.58,25 



o 



in degrees 82.14.34 



From the obfervations at Calcutta, it appears that 

 there is a difference between the Longitudes derived 

 from obfervations of immerfions and emerfions. 



The mean of Longitudes, 10 in number, 



derived from obfervations of immer- , lt 



fiom, with an 18 inch refle&or, was 5-53-53?77 

 Of emerfions (2) with the fame inftrument, 



was - - - - - 5.53.435 4 

 The fingle emerfion with Dollond\ triple 



objea glafs is - - - - 5.53.57, 8 



The mean of 4 emerfions with the fame - 5.53. 3, 9 



Difference by the refle6tor - - - o 0.10,77 



By Dollond's refractor - 0.00.54,90 



The mean of all the immerfions (11) - 5.53.54,13 



Emerfions (6) 5.53.17,4 



Difference 36,73 



As 



