SUM ATE A 
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 and 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. Not 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 high 
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 Malayan 
N 
