Distribution of Tropical Diseases in Africa. 427 
great difference, and that it is not climate alone which 
influences disease and mortality. 
The general salubrity of any place may be ascertained 
from the death-rate; in fact it is the only criterion we have. 
A low death-rate—say 20 per thousand—indicates that the 
climate and sanitary surroundings must be geod. If the 
death-rate be, say 60 per thousand, either climate or 
sanitation must be at fault. In speaking of a “bad” 
climate in Africa, it must not be forgotten that what is 
meant is that the climate is bad for emigrants from the 
temperate zone, not necessarily that it is bad for the natives. 
Take, for instance, the west coast of Africa. The climate is 
not on the whole fatal to natives, and their death-rate is not 
immoderately high, although the district goes by the name 
of “the white man’s grave.” There are, it is true, exceptional 
areas where even the mortality amongst natives is great, but 
so too in the temperate zone there are areas where, owing 
to faulty sanitation, overcrowding, and the like, a state of 
matters inimical to health, and inducing a high rate of 
mortality, is to be found. A few statistics, taken hap- 
hazard, will show what I mean. The death-rate in 
Edinburgh in 1887 was 19°8 per thousand; in Manchester 
in the same year, 28°7; in New York, 1878-80, 26:2; in 
Chicago, during the same period, 27:2; in St Louis, 193; 
in Calcutta, 31:1. 
Very much may be done to render even the worst climate 
in Tropical Africa more salubrious, and the sanitary pre- 
cautions, to which attention will be called in the sequel, 
will do a great deal to raise the health of the community. 
For instance, attention to the water-supply at Sierra 
Leone has had a very marked effect in lowering the 
death-rate; but when all is done, a permanent residence 
for inhabitants from the temperate zone is at present 
out of the question in the low-lying regions of Tropical 
Africa. 
We must now briefly consider the effects which the 
African climate exerts upon emigrants from the temperate 
zone, and which are chiefly the results of heat and moisture. 
For a short time after the arrival of such an emigrant in 
