594 
ON CORAL REEFS AS A CAUSE OF THE FEVER 
over the island must carry to sea the poisonous effluvium of the 
coral. In May 1848, I started early with Messrs. L. and B., to 
examine a cluster of islands about 15 miles to the westward of Sin¬ 
gapore and which excursion the reader will be able to trace by ex¬ 
amining the chart. The first island we reached was Pulo Damar, 
so named from rosin trees which once grew on it, and whose gigantic 
remains now shew how magnificent the primitive jungle was. 
This island is of small extent, and contains 10 houses and about 
50 people, some of whom have lived there for 20 years, the length 
of time of the establisment of the colony. The surface soil consists 
of Iron day-stone, mangroves surround the island, fruit trees and 
pine-apples grow on it and coral is to be seen more or less exposed, 
except in front of the houses. No fever has ever attacked the in¬ 
habitants. From this island we crossed to the mainland, but as I 
will advert to that in a subsequent part, we will proceed to the next 
island Pulo Pisf, a small spot of ground covered with pine-apples, 
with no coral exposed, although surrounded by an extensive reef, in¬ 
habited by 6 Chinamen, charcoal-burners, whose healthy looks con¬ 
firmed their statement that they never had fever. From this we 
passed to Pulo Sikra, the largest of the neighbouring islands except 
Blakang Mati. We found it to be an island of no elevation, surround¬ 
ed by a belt of mangrove trees, the primitive and secondary jun¬ 
gle having been entirely removed, while pine-apples cover the whole 
extent of the island, with a few fruit trees round the houses of the 
Bugis settlers, who are from 30 to 40 in number, and inhabit 6 
houses, the only habitations on the island. These houses are inland 
and separated from the sea by a belt of mangroves. A most minute 
investigation convinced me, as they themselves assured me, that they 
had no fever, nor ever had any, and that they w r ere not ignorant of 
what fever is may be inferred from one family contrasting their pre¬ 
sent healthy condition, to what it was when living on Blakang Mati 
island, when they were all affected with fever and lost many of their 
relatives. 
From this island we pulled to a contiguous one, called Serai, so 
named from the abundance of trees of that name which once grew 
upon it. We found the surface soil to be composed of iron-clay- 
stone, no jungle, but in its place fruit trees. A belt of mangroves 
surrounds the island except at the bay where we found the kampong 
or houses of the inhabitants. The houses were from 8 to 10 in num¬ 
ber built on the slope of the bill and faced the N.E. In front fill- 
