Appendix I
 

Most people are very much interested in how hot it gets in such tropics as we traversed. Unfortunately it is very difficult to tell them. Temperature tables have very little to do with the matter, for humidity varies greatly. On the Serengetti at lower reaches of the Guaso Nyero I have seen it above 110 degrees. It was hot, to be sure, but not exhaustingly so. On the other hand, at 90 or 95 degrees the low coast belt I have had the sweat run from me literally in streams; so that a muddy spot formed wherever I stood still. In the highlands, moreover, the nights were often extremely cold. I have recorded night temperatures as low as 40 at 7000 feet of elevation; and noon temperatures as low 65.

Of more importance than the actual or sensible temperature of the air is the power of the sun's rays. At all times of year this is practically constant; for the orb merely swings a few degrees north and south of the equator, and the extreme difference in time between its risings or settings is not more than twenty minutes. This power is also practically constant whatever the temperature of the air and is dangerous even on a cloudy day, when the heat waves are effectually screened off, but when the actinic rays are as active as ever. For this reason the protection of helmet and spine pad should never be omitted, no matter what the condition of the weather, between nine o'clock and four. A very brief exposure is likely to prove fatal. It should be added that some people stand these actinic rays better than others.

Such being the case, mere temperature tables could have little interest to the general reader. I append a few statistics, selected from many, and illustrative of the different conditions.

Locality.     Elevation  6am   noon  8pm  Apparent conditions
Coast             ---     80    90   76   Very hot and sticky
Isiola River      2900    65    94   84   Hot but not exhausting
Tans River        3350    68    98   79   Hot but not exhausting
Near Meru         5450    62    80   70   Very pleasant
Serengetti Plains 2200    78   106   86   Hot and humid
Narossara River   5450    54    89   69   Very pleasant
Narossara Mts.    7400    42    80   50   Chilly
Narossara Mts.    6450    40    62   52   Cold