30 Introduction : Seasons and Winds. 



As a general conclusion it may be stated that Borneo south of the equator 

 has its fine season during the months of our summer and its wet one in those 

 of our winter. A little north of the equator the conditions are much the same, 

 the differences being that the rainfall is more copious, and that the wet and 

 fine seasons commence a little earlier in the year. August, when the S.W. Mon- 

 soon of Asia is in full force, appears to be a very wet month here, as it is 

 also at Labuan, Mempakol, Gaya on the N.W. coast of the island, and at 

 Banguay Island off the north point of Borneo. On the N.W. coast the figures 

 from four stations show a strongly marked minimum rainfall in February; the 

 fine period appears to last for about three months only, January — April. On the 

 North and N.E. coast the true wet season takes place in the N.E. Monsoon and 

 the true dry season about the period of the shifting of the winds, February — May. 



Sumatra. — Dr. van der Stok shows that very varying conditions prevail 

 upon the different coasts of this great island. 



In the Malacca Straits land- and sea-breezes are general, neutralizing the 

 effect of the Monsoons. The wettest months along this part of the coast of 

 Sumatra are from October to December, the rains being apparently brought up 

 by the N.E. Monsoon out of the China Sea and the Straits. The dry months 

 are February and March, and also June and July, there being here, as in North 

 Borneo, a second rainy and fine period. 



At the northern end of Sumatra the S.W. Monsoon is much more marked, 

 being felt from May till October, and bringing the rains with it from the 

 Indian Ocean. February and March, when the E. Monsoon is blowing, are the 

 finest months. 



Along the N.W. coast down to the equator it is hard to speak of any 

 rainy — or one might better say of any fine — season. South of the equator 

 down to the Straits of Sunda the wettest months are from September to De- 

 cember, and the driest May to August, with a reduced rainfall in February. 



In South and S.E. Sumatra the INIonsoons are well marked, the dry season 

 being produced by the S.E. Monsoon from April or May till September, the 

 wet accompanying the northerly and westerly winds Avhich prevail from November 

 to March. 



The Bintang, Lhigga, Karimon, Thnhulan, Avamhas, Natuna, and Serasan 

 Islands: groups of small islands in the South China Sea between INIalacca and 

 Bangka and Borneo. — These islands receive the rains of both Monsoons and 

 are very wet almost the whole year, the greatest number of fine days occurring 

 in January, February and March. The climate is not considered unhealthy. 



Banka, BilUton atid the Straits of Karimata and Caspar. — Here the climatic 

 conditions are very changeable, varying on the land at different altitudes. The 

 greatest amount of wet is brought up by the N.W. Monsoon in November, 

 December and January; there is a minimum of rainf\ill in February, but tlie 

 driest months are July, August and September. In Banka the temperature on 

 the coast is given as 21"— 24"C. (17"— 19" K., 70"— 75" F.) during the night 



