SUMATRA 177 



monsoon sailing vessels are often five or six weeks in 

 making the passage from Singapore to Bangka Strait, and 

 squalls are common. 



The heavy squalls affecting the eastern lowlands of 

 Sumatra and the Straits of Malacca are as marked a 

 feature of this region as the " Bora " is of the Adriatic. 

 They are known to sailors as " Sumatras," and are gener- 

 ally accompanied by heavy rain aud thunder. They 

 occur most frequently during the S.W. monsoon, and are 

 supposed to be due to the obstruction offered to the 

 course of the wind by the Barisan chain. ISTot having 

 strength at all times to overcome this barrier the current 

 becomes pent-up and checked, and the condensed air 

 thus formed at high altitudes rushes down to displace 

 the heated and rarefied atmosphere of the east coast 

 lowlands, and driven by the pent-up force of the monsoon, 

 spreads far and wide over the straits. 



As in most equatorial climates rain occurs very 

 generally at all seasons of the year, and the fall is 

 excessively heavy, especially in the mountain districts. 

 At Padang on the west coast the average is about 187 

 inches, and at Palembang it is said to be still heavier. 

 This great humidity, combined with a continued higli 

 temperature, makes the island unhealthy, and the low- 

 lying alluvial plains of the east coast, half under water 

 for some months in the year, generate paludal fevers of a 

 severe type. Cholera, too, is more or less endemic, and 

 the almost equally deadly " beri-beri " annually claims 

 hundreds of victims. 



5. Fauna and Flora. 



Sumatra may be regarded as exhibiting, with Borneo 

 and the Malay Peninsula, the truly typical ]\Ialayan 



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