L— Astronomic Observations. 



get, taking account of the difference of longitude lietween Bujongolo and 

 Entebbe (-|- 9"" 45**), the daily mean correction Kj = — 2^" 123, which we shall 

 utilize for the determinations of position made in the period from 11th May to 

 nth June. 



Owing to an unforeseen circumstance, on the return journey, and after the 

 arrival of the expedition at Fort Xorth Portal, the No. 1 chronometer under- 

 went, like the others, a perceptible change in its movement. This was due to a 

 considerable delay which occurred in winding it, so that once it was necessary 

 to proceed to the revision of the longitude of Fort Portal which had been 

 determined on the outward journey. On the return, the conveyance of 

 Greenwich time from Bujongolo will be limited to this intermediate point, 

 since, owing to the above-mentioned change in the movement of the chrono- 

 meter, it would be impossible to convey said time to Entel)l)e for purposes of 

 control. 



Retaining the vahie of the daily correction just found (K^ = — 2« • 123) 

 as a quantity proportional to the time, and with the (approximate) latitude of 

 Fort Portal = 0' 39' 20" N., we get the value of the longitude from four series 

 of altitudes (Obs. Nos. 17, 18, 19, and 20), obtaining : 



Fort Portal.— 31st May. X = 2'' P" 32^-2 E.G. 



jj )i J) ^^ 31 'b ,, 



— '^l • 1 



JJ JJ J? — ox X ,, 



JJ JJ 5) ""'^ ' )J 



and as mean : 



Fort Portal A = 2i> 1'" 32«-5 E.G. 



a value which is adopted as the longitude of said i:)lace. 



The latitude of Fort Portal is obtained from a series of three circum- 



meridians oliserved on 31st May, and from meridian altitudes of 22nd and 



28th Jtily (Obs. Nos. 21, 22, 23, 75, and 86). The mean of the five results 



yielded for : 



Fort Portal (^ = 0° 39' 28" X. 



a value which differs little from that employed for the calculation of the 

 longitude. 



Using the longitude just found, we get the absolute correction of No. 1 

 chronometer at Fort Portal (return journey) by means of eight series of 

 ol)servations, as under : 



Fort Portal— 21st July, 4^ IP". ..Obs. No. 73; K^ = + 3'^ 1.5'" 16^- 1 



4 18 „ 74; „ = 15-9 



19 53 „ 76; „ = 17-5 



19 55 „ 77; „ = 16-5 



315 



