Appendix B. 
In fact, in spite of every care taken to make continual comparisons with the 
Fortin barometer, the term of correction did not keep constant, not only from 
day to day, but even during the same day whenever the instrument got shaken 
or was exposed to sudden changes of altitude. 
Hence, to avoid errors that might even be serious, a cautious and limited 
use has been made of the data obtained with the aneroid. Thus, the 
simultaneous indications of the Fortin and the aneroid being noted, and the 
altitude obtained from the former being taken as correct, the indications of 
the latter have served to establish differences of level, which were inconsiderable 
relatively to the point of comparison. When this process was completed the 
comparison was renewed, so that the data first obtained were brought under 
control. 
In general the reported data result from the mean of two or more 
determinations, and may consequently be regarded as sufficiently accurate. 
As to the altitudes of the places passed by the expedition on the return 
journey, that is, from and after the 14th July, these were all obtained by 
means of comparisons with the data observed simultaneously at Ibanda.* Then, 
for the sake of uniformity, they were reduced, like the previous ones, to the 
common level of Bujongolo. 
Amongst the determinations made relatively to Ibanda was that of 
Iolanda Peak, the altitude of which will consequently not be so near the truth 
as that of the other peaks. And, besides the inconvenience of Ibanda lying- 
still lower than Fort Portal, there was also the trouble caused by the breaking 
of one of the mercurial barometers, instead of which we had to use the 
hypsometer, which yields a less degree of approximation in the readings. 
N O T E. 
In the western districts of the Uganda Protectorate the geodetic survey 
has not yet been carried out, but the far-seeing British Government is taking it 
in hand, ancl no doubt it will soon be an accomplished fact. Hence it might 
seem reasonable to refer the various altitudes of the Ruwenzori group, not 
to Bujongolo, but to Fort North Portal, the exact height of which above 
sea-level will soon be known. In fact, this very critical point is being seen to 
by Messrs. H. Y. Tegart and II. E. Maddox, who have recently published some 
* For the altitude of Ibanda relatively to Fort Portal - 148 was assumed, this being the 
mean of the observations made on going and returning. 
368 
