TERRA AUSTRALIS. 
103 
Barrier Reefs.] 
the deep waves of the ocean, it is particularly well adapted to the 
purposes of a coasting trade. The reader will be struck with the 
analogy which this arm of the sea presents to one in nearly the same 
latitude of the northern hemisphere. The Gulph of Florida is formed 
by the coast of America on the west, and by a great mass of islands 
and shoals on the east ; which shoals are also of coral. 
On the outside of the barrier, the sea appears to be generally 
unfathomable ; but within, and amongst the reefs, there are sound- 
ings every where. Nor is the depth very unequal, where the bottom 
is sandy ; but like the breadth of the reefs and the arm they inclose, 
it diminishes as we advance northward, from 60 to 48, to 35, and to 
30 fathoms near our opening ; and to 20 at Cape Tribulation. The 
further to leeward, the shallower the water, seems to be a law 
amongst coral reefs. 
There is some variation in the tide in different parts of the bar- 
rier, but the most general rise is about two fathoms ; abreast of the 
Northumberland Islands, however, where the flood from the south- 
east seems to meet that from the northward, it is three fathoms, and 
perhaps more. The time of high water there, and also at the eastern 
Cumberland Islands, is eleven hours after the moon’s passage ; but 
it probably accelerates north-westward, to the opening, and then 
retards further on : at Endeavour River, captain Cook found it to be 
high water an hour and a half earlier than is above given. 
It has been said, that the width of the opening by which we 
got out to sea, is uncertain ; it is undoubtedly four, and possibly 
more leagues, but there are many small, unconnected banks in it. 
To a ship desiring access to any part of the coast, south of Endeavour 
River, I should certainly recommend her to enter the inclosed sea by 
the way of Break-sea Spit, if able to choose her own route ; but the 
question is, whether a ship driven by stress of weather, or by acci- 
dent, to seek the coast, might steer for the opening with a fair pros- 
pect of passing through in safety ? I certainly think she might ; with 
the precaution of not attempting the passage late in the day. The 
1802. 
October. 
