stance of about
thirty leagues to the N. N. W. from Break-sea Spit, commences a vast mass
of reefs, which lie from twenty to thirty leagues from the coast, and
extend past Broad Sound. These reefs, being mostly dry at low water, will
impede the free access of the tide; and the greater proportion of it will
come in between Break-sea Spit and the reefs, and be late in reaching the
remoter parts; and if we suppose the reefs to terminate to the north, or
north-west of the Sound, or that a large opening in them there exist,
another flood tide will come from the northward, and meet the former; and
the accumulation of water from this meeting, will cause an extraordinary
rise in Broad Sound and the neighbouring bays, in the same manner as the
meeting of the tides in the English and Irish Channels causes a great
rise upon the north coast of France and the west coast of England.

That an opening exists in the reefs will hereafter appear; and captain
Cook's observations prove, that for more than a degree to the north-west
of Broad Sound, the flood came from the northward. I found, when at
anchor off Keppel Bay, and again off Island Head, that the flood there
came from the east or south-east; but when lying three miles out from
Pier Head, there was no set whatever; and I am disposed to think that it
is at the entrance of Broad Sound, where the two floods meet each other.

CHAPTER IV.

The Percy Isles: anchorage at No. 2.
Boat excursions.
Remarks on the Percy Isles; with nautical observations.
Coral reefs: courses amongst them during eleven days search
for a passage through, to sea.
Description of a reef.
Anchorage at an eastern Cumberland Isle.
The Lady Nelson sent back to Port Jackson.
Continuation of coral reefs;
and courses amongst them during three other days.
Cape Gloucester.
An opening discovered, and the reefs quitted.
General remarks on the Great Barrier;
with some instruction relative to the opening.

[EAST COAST. PERCY ISLES.]

TUESDAY 28 SEPTEMBER 1802

On quitting Broad Sound, we steered for the north-easternmost of the
Northumberland Islands., which I intended to visit in the way to Torres'
Strait. These are no otherwise marked by captain Cook, than as a single
piece of land seen indistinctly, of three leagues in extent; but I had
already descried from Mount Westall and Pier Head a cluster of islands,
forming a distinct portion of this archipelago; and in honour of the
noble house to which Northumberland g