ISIS. 
March 16. 
23 . 
24 . 
60 SURVEY OF THE INTERTROPICAL 
These dangerous reefs were named Rowley’s 
Shoals, in compliment to the discoverer of the 
westernmost, (the Imperieuse) the situation of 
which is assigned by me to be 13' 30" to the east- 
ward of Captain Rowley’s account : the middle 
shoal, seen by us last evening, is certainly the 
one that Captain Clerke saw ; but the third or 
north-easternmost, distinguished by the Mer- 
maid’s name, seems to be a new discovery. 
On the north end of the Imperieuse shoal, 
rocks were distinguishable, and some were also 
seen near its centre above the level of the sea : 
all other parts w T ere under water. On the 
middlemost shoal no rocks were uncovered ; but 
on the south-east end. of the Mermaid’s Shoal, 
several were observed. These reefs are of a 
coral formation, and are very dangerous to ap- 
proach at night, from their vicinity being unfa- 
thomable to the depth of 170 fathoms; still, how- 
ever, the surf that constantly breaks upon them 
may be heard at a great distance, and will 
generally be sufficient to warn the navigator of 
his danger. 
On the 23d we passed the meridian of Cape 
Van Diemen, in latitude 10° 48'. The same 
evening some land was indistinctly seen bearing 
South. The ensuing daylight discovered to us 
several islands in the S.S.E., having previously 
