I06 SCIENCE IN AFRICA 



dicity, there is no evidence that total rainfall has suffered any 

 reduction during the fifty years in which records have been kept. 



Two valuable contributions in English on the coastal region are 

 by Gautier (1933) on French Guinea, and Braby (191 3) on the 

 harmattan wind. 



Meteorological data for the Sahara are by no means numerous, 

 but the new principal stations at Gao, Aquelhock, Tamanrasset, 

 and Regan will provide serial records before long. A notable 

 paper is that of Brooks and Mirrlees (1929) on records made by 

 Francis Rodd whilst travelling in the Sahara, mainly in A'ir during 

 1922-7. An extreme maximum air temperature of 114° F. was 

 recorded in June, and an extreme minimum, slightly below freez- 

 ing point, in December. The most interesting data, however, are 

 afforded by the humidity readings. The relative humidity varied 

 between 82 per cent, and 2 per cent., and the absolute humidity 

 or pressure of aqueous vapour between 22 mb. and i mb., indi- 

 cating that while the air of the Sahara desert is at times almost 

 dry, it can at times contain more moisture than is practically ever 

 contained in the air of England. In tropical latitudes the air even 

 in deserts cannot remain dry for any length of time because of the 

 incursion of moist winds from surrounding regions. 



In the Cameroons and neighbouring territories, the conspicuous 

 climatic feature is the high rainfall. Here the ordinary equatorial 

 rain-belt is reinforced by the south-west monsoon blowing on to 

 the mass of Mount Cameroon which attains some 13,000 feet 

 above sea-level. Under the German administration a number of 

 private rainfall stations were set up, and an important paper by 

 Semmelhack (1933) on the rainfall of Debundja, one of these 

 stations near the south-western foot of Cameroon Mountain, 

 analyses a forty-year record. It is pointed out that, with an aver- 

 age of 350 inches a year, Debundja is the wettest spot near sea- 

 level so far known in the world, and that in all probability the 

 higher levels of Cameroon Mountain are wetter than the very wet 

 mountain stations in the Khasi Hills of Assam and in Hawaii. As 

 this enormous rainfall is spread over 261 days in the year, the cli- 

 mate is extremely rainy. In 191 9, according to Semmelhack, as 

 much as 532 inches fell, compared with only 273 in 1909. The 

 greatest fall in 24 hours is 18 inches, but this is not outstanding for 



