DESCRIPTION OF THE EXPEDITION. 49 
with an equal number of spiders which preyed upon them, as well as earwigs, cock- 
roaches, and an occasional scorpion and centipede. Rats abounded, scavenging the 
barachois-flats at low tide for anything that might be left behind. 
On the morning of July 13 at 6 a.m. we weighed anchor for Egmont, intending to 
sound round Diego Gargia and between the two atolls. At different depths off the 
north of Diego Garcia we took water-samples for the gases and salts in solution. ‘The 
former were taken in vacuum-tubes of about 300 c.c. capacity drawn out to fine points 
at either end. The finer end being inserted into the tap of the water-bottle, the cock was 
turned so that the point was broken and the tube was filled from its contents, the broken 
end being subsequently resealed. The soundings taken showed that Diego Garcia is 
rather steeper in its slopes than any of the atolls to the north of Great Chagos, and also 
Fig. 21. 
View in Barachois Silvain, Diego Garcia. 
that the general depth of the whole Chagos bank is apparently rather greater in its 
southern half. 
On the following morning we anchored off the entrance to the north of Egmont Atoll, 
with a heavy swell running and a strong wind from the south-east. To secure good 
anchorage on the outer slope of an atoll is always a difficult matter, as the shore-platform 
may be so smooth as to afford no holding ground or so rough that the anchor fouls and 
is lost. A ship should never anchor to windward, but to leeward no danger need be 
apprehended, as she would only drift into deeper water. This is what happened to us, 
and we soon found ourselves a mile to the north with the anchor and 60 fathoms of cable 
over the bows. Steaming up we re-anchored about 120 yards from the reef, and at once 
lowered the ‘ Xanthus’ to explore the passage and find a suitable camping-ground. As 
the court-house and estate-office on Ile Sudest were offered to us by M. de Comarmond, 
SECOND SERIES,—ZOOLOGY, VOL. XII, 8 
