458 Proceedings of the Royal Physical Society. 
prevalent in the centre of the island; dysentery, on the other 
hand, occurs more frequently on the coast. Diarrhcea is met 
with all over the island; phthisis is said to occur in the 
higher regions, but, with the exception of pneumonia, diseases 
of the chest are comparatively rare. Rheumatism, leprosy, 
and syphilis are common. bBeri-beri occurs in epidemics ; 
diseases of the liver are fairly common. 
The Seychelle Islands, situated between 3° 30’ and 5° 30'S. 
latitude, are on the whole healthy. The mean annual tem- 
perature is about 77° F., the mean annual variation about 
15° F., and the mean annual rainfall about 80 inches, 
Malaria is practically unknown, and diseases of the chest, 
with the exception of phthisis, are rare. The chief diseases 
of these islands are dysentery, phthisis, and affections of the 
liver. Leprosy and syphilis are fairly common. 
Mauritius, an island lying between 20° and 20° 30’ §, 
latitude, is hilly, and has an elevation of from 500 to 700 
feet. The mean annual temperature at St Louis is 78° F, 
April to November is the coolest part of the year. The 
rainfall is 70 inches. Up to the year 1866 the island was 
free from malaria, but since then it has been very malarious, 
both intermittent and remittent fevers being exceedingly 
frequent. The so-called bilious remittent fever is very 
common, and typhoid fever is also frequently met with. 
Dengue is epidemic; dysentery and diarrhcea are common, 
so are leprosy and syphilis; probably also beri-beri. 
Elephantiasis arabum is endemic. Chest affections are 
comparatively rare; but phthisis is sometimes seen. 
Ophthalmia is exceedingly prevalent, and hepatitis seems 
general amongst the white population. 
The foregoing summary of the climatology of the various 
artificial regions into which I have divided Africa, and the 
account of the distribution of diseases occurring in them, 
has necessarily been somewhat dry and tedious; indeed, it 
has been very difficult to compress the necessary information 
within at all reasonable limits. I have now to give a general 
statement as to the nature of the prominent diseases met 
with in Africa, their cause. and prevention, and the methods 
