430 Proceedings of the Royal Physical Society. 
I, NORTHERN AFRICA. 
This part of Africa has its climate modified by its proximity 
to the Mediterranean and Atlantic, and also by the ranges 
of mountains running parallel to, though at some distance 
from, the coast. It naturally falls into various political 
divisions. 
1. Morocco is a dry and healthy country. It has a moist 
and fairly equable climate. There are two seasons— 
September to May being the winter, in which the rainfall 
is about 30 inches, and the temperature varies from 50° F. 
to 65° F. The summer, almost rainless, has a temperature 
of 65° to 80° F._ Throughout the whole year the daily varia- 
tion of temperature is remarkably slight. 
The diseases specially met with in Morocco are dysentery 
and diarrhoea, which are very prevalent along the coast; 
and leprosy, syphilis, and ophthalimia, which are very common 
throughout the whole country. Chronic rheumatism is 
prevalent, scrofula not uncommon, but respiratory diseases 
and the eruptive fevers, with the exception of small-pox, are 
rarely seen. Malaria, manifested by intermittent fever, only 
obtains in a slight degree. Epidemics of cholera have fre- 
quently visited this country, as also all the countries included 
in Northern Africa. 
2. Algeria—This country must be divided into two parts 
—the sea-coast district, called the Tell, and the elevated region 
beyond, extending to the summits of the mountains, which 
have an altitude of from 3000 to 8000 feet. The mean 
annual temperature is about 65° F., the mean diurnal varia- 
tion 42° F., the nightly variation 36° F. The average relative 
humidity is about 45 per cent. The rainfall varies in 
different districts, but the average at the coast is about 900 
mm. The rain commences late in October, and ends about 
the end of March, autumn and winter occurring within this 
period. Spring begins in the middle of March and ends in 
June; July, August, and September being the summer 
' months. There is a greater amount of disease in Algeria 
than either in Morocco or in Tunis and Tripoli. The death- 
rate from typhoid fever. is slightly over 11 per 1000, this 
