104 SCIENCE IN AFRICA 



declines rapidly southward towards the Sahara. The Tell plateau 

 has a continental climate. In spite of intense summer heat, heavy 

 snowstorms occur now and then in winter at 2,000 feet. 



For Algeria there are two important papers by Franc (1923) and 

 Prat (1929). The second is of special interest in showing the bene- 

 ficial influence of fog-moisture in rainless regions. On the south 

 side of the Murdjadjo range, which faces the scorching winds of 

 the Sahara desert, there is no vegetation on the lower slopes, but a 

 xerophilous type flourishes precisely down to the level reached by 

 heavy nocturnal mountain mists. The northern flank of the range 

 comes under the influence of heavier rainfall and is forested. 



For Morocco three important papers are those of Bernard (1922), 

 Wattier (1926), and Russo (1931). The Moroccan littoral is rather 

 cool for its latitude, subject to copious night dew and mist, as well 

 as a liberal winter rainfall. In the interior the rainfall diminishes 

 and the summer heat is severe at low levels, but great local com- 

 plexity of climate results from the influence of the Atlas range. 

 Although one or two peaks actually reach the limit of perennial 

 snow, it may be said of the Great Atlas as a whole that at 12,000 

 feet it just manages to clear itself of snow for a short time in summer 

 — much in the same way as the Scottish Grampians do at 4,000 

 feet in a much colder latitude. But there is indisputable geological 

 evidence that during the pluvial epoch, which was contempor- 

 aneous with the pleistocene ice age in Europe, the Atlas mountains 

 bore powerful glaciers. 



The meteorological services o{ French West and Equatorial Africa} 

 and the French Cameroons v/ere reorganized in April 1929 and 

 have developed noticeably since that date. Each of these ad- 

 ministrative areas has now an efficient independent service, 

 centralized and correlated by a special department of the Min- 

 istry for Colonies in Paris under M. Hubert. The service in West 

 Africa, under M. L. Welter, was estabHshed in 1931. There are 

 nineteen principal stations, each in charge of a qualified meteoro- 

 logist, where observations are made on the ground and in the 

 upper air with pilot balloons, on temperature, pressure, humidity 

 and wind velocity, some of these being observed hourly and others 



* It is convenient to include French Equatorial Africa in this group for reasons of 

 its organisation, although it really belongs to the Central climatic region. 



