30 REPORT OF THE HARVARD AFRICAN EXPEDITION 
the dry season, the vegetation becomes parched, particularly when the north- 
east wind, the ‘‘harmattan,” is blowing, when the atmosphere becomes mark- 
edly dry. At that season of the year, although the nights may be a little cooler, 
the days are often hotter, for the sky is frequently almost cloudless. It is a 
mistake to suppose that because the harmattan breeze is blowing it is always 
a cool breeze. These winds, which blow from the Sahara Desert, are extremely 
dry and often dusty. By the time they reach Liberia their intensely dry char- 
acter is more or less modified by their having passed over the Liberian forests 
and the upper Niger region, which is well watered. However, while they are 
more or less dry winds, they may be either cool or warm. The harmattan 
has rarely any appreciable effect on the mean temperature, and feels cool 
to one only because of its dryness and because of the accelerated evapora- 
tion of moisture upon the skin which it causes. On the coast these winds 
sometimes raise the midday temperatures, although they may render the morn- 
ing and the late evening cooler. In the interior the harmattan may be a hot, dry 
wind, and it is sometimes accompanied by a haze due to the fine particles of 
red dust that it carries. 
The unhealthiness of the coast is particularly due to the combination of ex- 
cessive humidity with continuous and considerable, but not excessive, heat. 
The very severe rainfall and humidity are by far the most important climatic 
factors in Liberia. Mosquitoes prevail especially after the beginning of the rainy 
season and at its close. The rainy season is the most unhealthy, particularly on 
or near the coast, and fever then prevails especially among foreigners who do 
not take proper precautions and who are less immune than the natives, and to 
whom the moist heat makes any physical activity particularly disagreeable. 
Liberia has the reputation of possessing one of the most unhealthy climates in 
the world, and the coast has long been known as the ‘‘white man’s grave.” 
An old sailor’s proverb says of the coast that ‘‘There’s two comes out where 
three goes in.” 
A great deal, of course, can be done through sanitation to reduce the amount 
of infectious disease, particularly that spread by the blood-sucking and other 
Diptera. However, it is the enervating effect of the climate upon foreigners, 
occasioned by the continuous heat and moisture, that is most noticeable. After 
nine o’clock in the morning it is unpleasant to walk if one is exposed to the sun, 
and by ten or eleven o’clock the heat and moisture begin to be noticeably op- 
pressive. One perspires throughout the day, even in the house. In many parts 
of the tropical world one is quite ready, by five or half past five o’clock, to re- 
fresh one’s self by exercise by means of some sport. Not so in the villages 
of Liberia on the seacoast. Here, on account of the humidity and the heat, one 
must, so to speak, drive one’s self to take any form of exercise. When one con- 
siders that the towns on the Coast have an average mean temperature of from 
76° F. to 80° F. and a seasonal variation of very few degrees, and that the air is 
so often nearly saturated with moisture, it will be seen that they are not likely 
to become ideal places of residence for foreigners. 
However, the interior of the country is considerably more salubrious. In 
