The wind blew fresh from the eastward all night, and raised a short swell which tried the ship more than any thing we had encountered from the time of leaving Port Jackson; and I was sorry to find, brought on her former leakiness, to the amount of five inches of water per hour. We tacked to the south, soon after mid-night, and to the northward at three in the morning [WEDNESDAY 20 OCTOBER 1802]. Holborne Isle was seen bearing S. 6° W., four or five leagues, at daylight; and at seven we passed between three small reefs, of which the easternmost had been set at W. S. W. on the preceding afternoon. In half an hour, when the latitude from the moon was 19° 14', and longitude by time keeper 148° 21½', distant high breakers were seen to the north and eastward; the nearest small reef bore S. W. ½ W., two miles, and a much larger one extended from N. ½ E. to W. by N. The passage between these two being three miles wide, we bore away through it; and in following the south side of the great reef, left another, five or six miles long, on the larbord hand, the passage being equally wide with the former, and the least depth 21 fathoms. Soon after ten o'clock, we steered northward, round the west end of the great reef.
At noon, the latitude from observations to the north and south was 19° 8' 15", and longitude by time keeper, 147° 59' east. No land was in sight, and the high breakers were lost in the eastern quarter; but we had detached reefs in the N. E., the N. E. by N., and W. N. W., distant from two to five miles. Towards the north there was six points of clear water, and I steered onward till near three o'clock; when, besides two new reefs already passed, one on each side, we had five others: two in the E. by N. at the distances of one and five miles. one E. S. E. four miles, another N. W. by W. six miles, and a fifth N. W. by N. three miles. Whether to steer onward amongst these, and trust to finding shelter for the night, or to run south-westward towards the land, and get within all the reefs before night came on, was an important, but difficult point to decide. The reefs in sight were small, and could not afford shelter against the sea which was breaking high upon them; but these breakers excited a hope that we might, even then, be near an opening in the barrier; and although caution inclined to steering back towards the land, this prospect of an outlet determined me to proceed, at least until four o'clock, at the chance of finding either larger reefs for shelter, or a clear sea. We were successful. At four, the depth was 43 fathoms, and no reefs in sight; and at six, a heavy swell from the eastward and a depth of 66 fathoms were strong assurances that we had at length gained the open sea.
The topsails were then treble reefed, and we hauled to the wind, which blew strong at E. S. E., with squally weather. At eight, hove to and sounded: no ground with 75 fathoms; and at twelve, none with 115. But the wind unfortunately headed two points; and the probability of meeting unknown reefs being thereby much increased, I tacked to the southward at one in the morning [THURSDAY 21 OCTOBER 1802]; preferring, if we must of necessity be again driven amongst them, to come in where we knew of an opening, rather than where their formation was totally unknown.
At four, tacked ship to the northward, and sounded with 100 fathoms, no bottom. At daylight, no reefs could be seen from the mast head, the wind had moderated its strength, and we made all possible sail to the N. by E.; keeping two points free, to make the ship go through the water. We now considered ourselves entirely clear of the reefs; but at noon high breakers were seen extending from West to N. N. W., at the distance of six or seven miles, and we hauled up a point more to the eastward. Our latitude was 17° 54', longitude 148° 37', and at the depth of 100 fathoms there was no ground; the variation observed in the morning, with three azimuth compasses, was 6° 8' east, corrected to the meridian. Another reef was discovered at two o'clock, lying nearly three leagues to the northward of the former; but although there were many boobies, and tropic and man-of-war birds about, no more dangers had been descried at dusk; nor did we see any more until approaching Torres' Strait.
I shall conclude this chapter with some general remarks on the reefs, which form so extraordinary a barrier to this part of New South Wales; and amongst which we sought fourteen days, and sailed more than five hundred miles, before a passage could be found through them, out to sea.
The easternmost parts of the barrier seen in the Investigator, lie nearly in 21° south and 151° 10' east; but there can be no doubt that they are connected with the reefs lying to the southward, discovered in 1797 by captain Campbell of the brig Deptford; and probably also with those further distant, which captain Swain of the Eliza fell in with in the following year. If so, the Barrier Reefs will commence as far south-eastward as the latitude 22° 50' and longitude about 152° 40', and possibly still further; Break-sea Spit is a coral reef, and a connexion under water, between it and the barrier, seems not improbable. The opening by which we passed out, is in 18° 52', and 148° 2'; so that, did the Barrier Reefs terminate here, their extent would be near 350 miles in a straight line; and in all this space, there seems to be no large opening. Mr. Swain did, indeed, get out at the latitude 22°; but it was by a long, and very tortuous channel.
Of what extent our opening may be, is uncertain; but since captain Cook had smooth water in running to the west and northward to Cape Tribulation, where he first saw the reefs, it should seem to be not very great; certainly, as I think, not exceeding twenty, and perhaps not five leagues. I therefore assume it as a great probability, that with the exception of this, and perhaps several small openings, our Barrier Reefs are connected with the Labyrinth of captain Cook; and that they reach to Torres' Strait and to New Guinea, in 9° south; or through 14° of latitude and 9° of longitude; which is not to be equalled in any other known part of the world.
The breadth of the barrier seems to be about fifteen leagues in its southern part, but diminishes to the northward; for at the Northumberland Islands it is twelve, and near our opening the breadth is not more than seven or eight leagues. The reefs seen in latitude 17¾°, after we got through, being forty leagues from the coast, I consider to be distinct banks out at sea; as I do those discovered by Mons. de Bougainville in 15½°, which lie still further off. So far northward as I explored the Barrier Reefs, they are unconnected with the land; and continue so to latitude 16°; for, as before said, captain Cook saw none until he had passed Cape Tribulation.
An arm of the sea is inclosed between the barrier and the coast, which is at first twenty-five or thirty leagues wide; but is contracted to twenty, abreast of Broad Sound, and to nine leagues at Cape Gloucester; from whence it seems to go on diminishing, till, a little beyond Cape Tribulation, reefs are found close to the shore. Numerous islands lie scattered in this inclosed space; but so far as we are acquainted, there are no other coral banks in it than those by which some of the islands are surrounded; so that being sheltered from 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 soundings 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.