Appendix B. 



At the Entebbe Obser\atory the meteorological observations were regularly 

 carried out three times in the day, at 7, 14 and 21 of mean local time, which 

 differs '2 hours, 8 minutes and 45 seconds from mean Greenwich time, whereas 

 those of barometric pressure during the journey could ])e made only at noon 

 of local time. 



Hence in the absence of synchronous corresponding data of Entebbe, for 



the pressure the mean of the hours 7, 14 and 21 has been assumed, and from 



this mean the pressure at noon may, generally speaking, l)e taken to differ but 



slightly. For the temperature and the tension of aqueous vapour that of 



the nearest hour, that is 14, has been assumed. In Table II have l)een brought 



together the data of the observations made at Entebbe* between 16th and 



28th May. From the data supplied by the two Tables I and II were calculated 



the altitudes of the various stations relatively to Entebbe l)y means of the 



formula : f 



' 1 \ 



Z = 18400 (1,00157 + 0,00:367 0) ; - 



^1 - 0,378 ^j 

 (l+0,00259cos2X)(l + |±^)log| 



where Z expresses the difference of level between the two stations. 

 H„ the pressure reduced to 0" in the lower station. 

 H the pressure reduced to 0" in the upper station. 



^ = -^.^ -tlic mean lictween the temperature Z,, of the air in the lower 



station and that of / in the uppei' station. 



mean between the vapour teni 



and /" that of the upper station. 



= -^ " the mean between the vapour tension /, in the lower station 

 H„ + I I 



\ the latitude, 



z the latitude of the lower station a1>()ve sea-level. 



The headings II, „ /,„ yj,, H, /, /', which ligure above the columns in the 

 fiillowing tables, I'efer to the use of the fornuda for the calculation of which use 

 has been inaile nf the "Tables Météorologiques internationales " (Paris, 1890). 



* According to the certificate of tlie " National Physical Laboratory," the barometer of 

 the Entebbe Observatory has a correction of — O'OOl inch. 



t Tliis fonnula of Kiihhnann has been adopted without mure iulo as tlie most {ijencnil mid 

 complete, since a discussion on tlic clioice of altiinetrie formulas, which sliould take account 

 of the recent resulls on the liiw of variation of the meteorological elements in tlie open air 

 and on the slopes of tlic mountains, would not l)e in accord witli the few availalilc data, data 

 ■which, moreover, cannot always be obtained under tlie best conditions. 



362 



