Appendix B. 



In fact, the temperature being 23' "9 Celsius (75' F.) at Fort Portal, and 

 r-6 Celsius (34^-4 F.) at Edward Peak, a difference of 22 = -3 Celsius (72'-6 F.), 

 if the decrease occurred proportionately to the altitude the temperature of 

 Bujongolo should be about 7' "2 Celsius (45" F.), whereas it is only 3°*9 Celsius 

 (39°'7 F.). This, therefore, means that the column of air has a lower temperature* 

 than is assumed by the theory, so that to an equal difference of pressure 

 corresponds a less difference of altitude. 



Lastly, in connection with determinations of this n;iture, it is not to be 

 forgotten that results now well established are : — 



1. That heights calculated by means of thermo-barometric observations 

 are generally found to be greater with measurements made b}' day compared 

 with those made by night. They present a considera1)le daily range with the 

 maximum value shortly before the maximum daily temperature, and the 

 minimum one or two hours before sunrise. The extent of range is influenced 

 by the season, the local conditions, and the state of the sky. 



2. That the altitudes calculated with the mean daily or monthly values of 

 the observations are found to be too low in winter and too high in summer ; 

 with the annual mean they differ little from the actual heights. 



* Caused probublv hv the great masses of ice on Ruwenzori. 

 370 



