viii PREFACE. 
to me the following request and advice on the 
subject : — 
"79 Eccleston Square, 1st June 1864. 
" My dear Grant, — I really wish you would write your 
experiences in Central Africa, from Kaze to Gondokoro. In 
doing so, try as much as possible to give, relatively, a corre- 
sponding valuation to each succeeding country, in the order 
in which you passed through them — I mean, as regards the 
products and the capabilities of the countries, the density of 
their populations, and the different natures of the people, as 
well as the causes affecting them. Personal anecdotes, espe- 
cially illustrative of the superstitious inclinations of the peo- 
ple, will be most interesting. But nothing can be of such 
permanent value to the work as a well-defined account of the 
rainy system and its operation upon vegetable life, showing 
why the first three degrees of north latitude are richer than 
the first three in the south, and how it happens that the 
further one goes from the equator, the poorer the countries 
become from want of moisture. I maintain that all true 
rivers in Africa — not nullahs — which do not rise in the 
flanking coast ranges, can only have their fountains on the 
equator ; but the people of this country have not learned to 
see it yet. — Yours ever sincerely, 
"J. H. Sfeke." 
I shall not attempt to comment upon the rain-sys- 
tem of the elevated land we traversed at the equator, 
but merely remark that in this region fruitful showers 
were constantly falling like dew. The influence of 
these showers was, that although the flora was not so 
tropical as in countries which are at a far lower ele- 
vation, and though this quarter of the globe, from all 
