I.— Astronomic Observations. 



get, taking Mccount of the ditFerence of longitude between Bujongolo and 

 Entel>l)e ( -|- 9™ 45"), the daily mean correction K, = — 2"- 123, which we shall 

 utilize for the determinations of position made in the pei'iod from 11th Maj' to 

 11th June. 



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

 arrival of the expedition at Fort North 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 lie 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 Enteblie for purposes of 

 control. 



Retaining the vahie of the daily correction just found (Kj = — 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, is, 19, and 20), obtaining: 



Fort Portal.— 31st May. X = 2i' 1'" 32^-2 E.G. 



>J >1 >) =^ ol ■?> ,, 



)» )) J5 '^ ^ A „ 



and as mean : 



Fort Portal A. = 2'' 1"' 32^-5 E.G. 



a value which is adopted as the longitude of said place. 



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



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



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



yielded for : 



Fort Portal <^ = 0'' 39' 28" N. 



a value which difters 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 

 oljservations, as under ; 



Fort Portal.- 2 1st .hi]y, i'' 11'"... Obs. No. 73; K, = -H 3" 1.5'" 16'- 1 



4 18 „ 74; „ = 15-9 



19 53 „ 76; „ = 17-5 



19 55 „ 77; „ = 16-5 



315 



