2 
C. F. Oldham —Topography of the Arabian Sea. 
[No. 1, 
on “ The Mean Temperature of the Deep Wafers of the Bay of Bengal.”* 
Since then, owing to the survey of the Laccadives and the frequent 
passage of the “ Investigator ” past this group, a large number of deep 
soundings and temperatures have been accumulated in the Laccadive 
area. Advantage is now taken of these soundings to draw a chart 
shewing the contours in this region (see Plate I). 
In the latitude of Bombay the hundred-fathom line is distant 
about one hundred and twenty miles, the soundings deepen seaward 
from the coast gradually, forming a shelf, which narrows on proceeding 
southward, until in the latitude of Cape Comorin it is only thirty miles 
broad. 
The general slope seaward, beyond the hundred-fathom line, is from 
two to three degrees : it is broken occasionally by ridges or spurs of 
comparatively shoal water, and in latitude 11° N. a ridge, on which are 
situated the Elicalpeni Reef and Androth Island, projects for fifty 
miles to the south-west. In the Laccadive area the eleven hundred 
fathom line encircles the whole group, connecting the reefs at this depth 
with the neighbouring slope from the coast of Hindustan. Two tongues 
of deeper water narrow the connection with the slope from the coast, 
and an extensive tract of depths over eleven hundred fathoms occupies 
a position east of the Laccadives, on a line between the tongues. 
The western islands and reefs are all situated on an extensive plateau 
of under a thousand fathoms, and are separated from the eastern by 
a narrow flat, averaging a thousand and twenty fathoms. The most 
northern of the group is a submerged reef, situated on the eastern side 
of a plateau of under nine hundred fathoms ; the next two are also 
submerged reefs, rising from a similar plateau ; south of these are three 
lagoon reefs, likewise connected by depths under nine hundred fathoms; 
and still further south are two groups each containing two reefs, and 
three isolated reefs, all rising from similar depths. The eastern reefs 
consist of three, namely, the two northern, situated on the ridge already 
mentioned as jutting out from the coast slope, and another island rising 
abruptly from depths of eleven hundred fathoms. 
Minikoi, in lattitude 8° 15° N., sometimes spoken of as being one 
of the Laccadives, is separated from that group by depths of over 
twelve hundred fathoms, but has a submarine connection with the 
Maldives to the southward. 
The outer slope from the plateau on which the islands are mostly 
situated is gradual, until the floor of the ocean is reached in depths a 
little over two thousand fathoms. 
Soundings and temperatures obtained during the months of October 
# J. A. S. B., Yol. LVI., Pt. II., 1887, pp. 230-232. 
