I08 SCIENCE IN AFRICA 



Nigeria took an active part in the Polar Year observations of 

 1932-3, and the results have been printed in a special publication 

 (Nigeria 1934) which includes data obtained at eight selected 

 stations. In 1933 the Survey Department published two rainfall 

 and wind maps, for November to April (dry season), and April to 

 May (wet season). A particular feature of the Southern Provinces 

 is the short dry season in July and August, which divides the rainy 

 season into two. This is of great importance to agriculturalists in 

 that it allows two crops to be raised during the year; it has never 

 been satisfactorily explained by meteorologists. 



In the Gold Coast meteorological services are divided between the 

 Agricultural and Survey Departments. The former is responsible 

 for ninety-three observation stations for rainfall and some of these 

 record also temperature, pressure, humidity, and winds. Some 

 trouble has arisen concerning the records of temperature, in that 

 thermometers have shown remarkable diversity of performance 

 after a few years' work in the Gold Coast climate. 



A map of annual rainfall is published every year for the Gold 

 Coast, and in 1930 a rainfall chart was prepared for the whole 

 of West Africa, including French territory (West Africa 1930). 

 The climate has been described in the bulletins of the agricultural 

 department by the Director of Agriculture, G. G. Auchinleck 

 (1926a and 1926b) and by N. P. Chamney (1928). An important 

 problem with regard to rainfall is concerned with the effect of the 

 escarpment in Ashanti. This ridge of high land, running across the 

 territory from north-west to south-east, appears to control precipi- 

 tation, and hence coincides with the limit of forest land and cul- 

 tivation of cocoa. Observation centres for rainfall north of the 

 escarpment are, however, very few, so that the rainfall map can be 

 regarded as only approximate. The heavy precipitation on the 

 coast near Axim remains unexplained, but it has been suggested 

 that the moisture-laden winds from the Gulf of Guinea travel 

 north-east as far as the escarpment, where they rise, precipitate 

 part of their moisture and return towards the south-west to preci- 

 pitate most of their rain near the coast. 



The meteorological work necessitated by the extension of the 

 air route from Nigeria has been placed under the survey depart- 

 ment. Two complete stations are established, at Accra and Tak- 



