We left Tremouille Island in the morning, and passing round the north
side, soon came in sight of Clerke's, alias Ritchie's Reef. It was our
intention to have gone round the northern end of it, but the tide setting
two knots an hour forced us to the southward. In a line midway between it
and Tremouille the depth was 17 and 20 fathoms. The reef was nearly three
miles long, in a north-east and south-west direction, and one mile and a
half wide; the centre being partly dry. Two miles and a half South-West
by West of it we crossed a patch of 13 fathoms, with 22 and 25 fathoms on
each side, the northern part of Hermite Island bearing South 62 degrees
East fourteen miles, soon after which it was lost sight of from the poop.

The next afternoon a westerly wind brought us again in with the land; and
in the evening we tacked in six fathoms, three miles and a half to the
northward of Thevenard Island, which we found to be connected with a reef
we discovered in the morning, lying eleven miles North by East from it;
inside this reef the water looked deep and smooth. The island is a narrow
strip lying east and west, about three miles; the west end we made in
latitude 21 degrees 26 minutes South and longitude 114 degrees 54 minutes
East. From the number of islands I saw to the south of Thevenard, I think
the reef continues to Maison Island, near the North-west Cape. The outer
one, seen from the Beagle, is in latitude 21 degrees 31 minutes South and
longitude 114 degrees 42 minutes East. I myself believe the whole extent
from Maison to Barrow's Island is occupied by islets and reefs, probably
all connected. We know, in fact, from Captain King, that a reef extends
sixteen miles off the south end of Barrow's Island.

RESULT OF SOUNDINGS.

Seventeen miles in a North-West by North direction from Thevenard Island