Lieutenant Fowler had gone through the most essential duties, and the ship was nearly ready for sea; but on landing at the tents I found that the time keepers had been let down, and the business of finding new rates for them was to be recommenced.  This accident would require a week to be repaired; and being unwilling to remain so long inactive, I determined to leave Mr. Flinders at Upper Head, and take the ship over to the inner end of Thirsty Sound, where it appeared there was something to correct in captain Cook’s chart.

SATURDAY 18 SEPTEMBER 1802

The Lady Nelson had lost two sheets of copper, and the trunks of the sliding keels required some reparation; I therefore desired lieutenant Murray to lay his vessel on shore and get these matters arranged, to cut wood for himself, and be ready to sail in a week for Torres’ Strait; and his stock of water was completed out of the Investigator.

SUNDAY 19 SEPTEMBER 1802

On the 19th in the morning we unmoored the ship, and a little before low tide stretched over towards Thirsty Sound; but the numerous shoals to be encountered, and which cannot be concisely described otherwise than in a chart, caused much delay; and it was near noon of the day following [MONDAY 20 SEPTEMBER 1802] before we anchored at the south end of Long Island, in 3 fathoms, and about one mile from the low mangrove shore.  At the south end of the island was a small hill, bearing S. 55 deg.  E. one mile and a half from the ship, where I landed with a party of the gentlemen; it forms the west point of the inner entrance to Thirsty Sound, as some low red cliffs, one mile and a half distant, do the east point; but a shoal, dry at low water, lies in the middle, and the channels on each side are not calculated for a ship.  The small hill was found to be on a detached islet one mile long, the greater part of which is mud covered with mangroves; the hill is partly excavated by an arched way running through it, and the stone is of a mixed red and white colour, and of an ochry consistence.  From the highest top, I set: 

Upper Head, bearing S. 28 deg. 22’ W.
Double Mount.  S. 53 20 E.
Pine Mount, S. 61 5 E.

These bearings place the inner end of Thirsty Sound in latitude 22 deg. 16’; and curtail the distance of thirty miles from Pier Head in captain Cook’s chart, to twelve miles and a half.

TUESDAY 21 SEPTEMBER 1802

On the 21st, the botanical gentlemen went over in the launch to the east side of Thirsty Sound, the main land having been always found more productive in the objects of their pursuit, than any island however large.  I went to examine along the west side of Long Island; but had not proceeded two miles before an opening presented itself amongst the mangroves.  It led to the eastward, and then separated into two branches; and in following that which trended north-east I came into Thirsty Sound, and landed five miles above the inner entrance, at an islet in mid-channel, which had been set from Pier Head and is laid down by captain Cook.