558 Voyage of the Novara. 



clouds suddenly rose and disappeared above the dark blue 

 surface of the sea, flickering here and there like flames. This 

 was our first glimpse of the island-reef and the surf-beaten 

 coral, seen under the influence of a mirage, when, as is very 

 frequently the case in tropical climates, the temperature of 

 the surface of the water, and consequently of the immediately 

 adjacent strata of atmosphere, is higher than those next above. 

 Having got within about a couple of miles, the dark points 

 resolved themselves into verdant cocoa-groves, patches of 

 which adorn the outermost reef, while the small clouds now 

 proved to be the tumultuous lash of a tremendous blinding surf, 

 on the reef which separated the rise and fall of the ocean out- 

 side from the smooth placid surface of the broad channel, which 

 inside the ring-shaped coral reef forms those singular natural 

 canals, on which the natives in their frail canoes can sail 

 right round the island, sheltered from the violence of the 

 waves, and which, at those places where there is sufficient 

 depth, and a breach in the line of reef admits of ingress from 

 without, affords for even large sized ships a secure harbour, 

 according to observation in 6° 47' N., 158° 13' 3" E. 



We now endeavoured to enter between Nahlap Island on 

 the west, covered with cocoa-palms and bread-fruit, and 

 Sandy Island on the east, surrounded with a belt of raging 

 foam, its coral masses clothed with low scanty brushwood. 

 But almost immediately '' Halt " was once more the order. 

 In order to get into the harbour proj^er, which lay between 

 two majestic banks of coral rising from the level of the sea 



