The rise of _tide_ and time of high water have been mentioned; but it may be proper to say what I conceive to be the cause of the extraordinary rise in Broad Sound. From Cape Howe, at the southern extremity of the East Coast, to Port Curtis at the edge of the tropic, the time of high water falls between seven and nine hours after the moon"s pa.s.sage, and the rise does not exceed nine feet; but from thence to the northward, commencing with Keppel Bay, the time becomes later, and the rise augments, till, at Broad Sound, they reach eleven hours, and between thirty and thirty-five feet. The princ.i.p.al flood tide upon the coast is supposed to come from the south-east, and the ebb from the north, or north-west; but from the particular formation of Keppel and Shoal-water Bays, and of Broad Sound, whose entrances face the north, or north-west, this ebb tide sets into them, and acc.u.mulates the water for some time, becoming to them a flood. This will, in some degree, account for the later time and greater rise of the tide; and is conformable to what captain Cook says upon the same subject (Hawkesworth, III. 244); but I think there is still a super-adding cause. At the distance of about thirty leagues to the N. N. W. from Break-sea Spit, commences a vast ma.s.s 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 acc.u.mulation 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 pa.s.sage through, to sea.
Description of a reef.
Anchorage at an eastern c.u.mberland 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 cl.u.s.ter of islands, forming a distinct portion of this archipelago; and in honour of the n.o.ble house to which Northumberland gives the t.i.tle of duke, I named them _Percy Isles_.
(Atlas, Plate XI.)
At noon, the observed lat.i.tude on both sides was 21 51" 20"; the west end of the largest North-point Isle bore S. 18 W. three or four leagues, and the Percy Isles were coming in sight ahead. The weather was hazy; and the wind at E. S. E. preventing us from fetching No. 2, the largest isle, we tacked at five o"clock, when it bore S. 31 to 54 E, two or three leagues; No. 5, the north-westernmost of the cl.u.s.ter, bearing N. 24 W., two miles and a half. At dusk the anchor was dropped in 14 fathoms, sandy ground, two or three miles from some rocky islets which lie off the west side of No. 2. The flood tide at this anchorage came from the north-east, one mile per hour.
We got under way again in the morning [WEDNESDAY 29 SEPTEMBER 1802]; but the wind being light and unfavourable, and the tide adverse, I went off in the whale boat, accompanied by Messrs. Brown and Westall, to examine the pa.s.sage between the rocky islets and No. 2, directing lieutenant Fowler to follow with the ship when the signal should be made. We first landed at the islets, where the same kind of pine as seen at Port Bowen and other places, was abundant; and leaving the two gentlemen there, I sounded the pa.s.sage, which was a mile and a half wide, with a sandy bottom of 8 to 13 fathoms deep, and sheltered from all eastern winds. The signal was then made to the ship; and so soon as she was brought to anchor, I went to examine a little cove, or basin, into which the height of the surrounding hills gave expectation of finding a run of fresh water. The entrance is little more than wide enough for the oars of a rowing boat, the basin, within side, is mostly dry at low water, and the borders are over-run with the tiresome mangrove; but when the tide is in, it is one of the prettiest little places imaginable. In searching round the skirts, between the mangroves and feet of the hills, a torrent-worn gully was found with several holes of water; and one in particular, near the edge of the mangroves, where, by cutting a rolling way for the casks, the holds of the two vessels might be filled; and at a beach without side of the entrance to the basin, several hauls of the seine were made with good success.
THURSDAY 30 SEPTEMBER 1802
Early next morning, lieutenant Fowler landed with a party of men prepared to cut through the mangroves; but fresh water was discovered to ooze out from amongst them, much below high-water mark; and by digging in the sand at half ebb, our casks might be filled more easily, and with better water than in the gully. Whilst this duty was going on, the carpenters were sent to cut fire wood and pine logs upon the rocky islets, the botanical gentlemen followed their pursuits where it best pleased them, and my time was occupied in surveying. From a hill near the head of the basin, I took bearings of all the objects to the south and westward; amongst which, the five following were the most important to the connexion of the survey.
Mount Westall on the main (not distinct), S. 23 5" E.
Northumberland Islands, the 4th, a peak, S. 18 20 E.
Northumberland Islands, the 7th, station on the hill, S. 19 30 W.
Northumberland Islands, a peaked I. marked "h", S. 89 55" to N. 87 35 W.
Northumberland Islands, high northmost, marked "i", N. 57 0 W.
The circle was completed in the afternoon, from a higher part of the island near the north point; and the weather being tolerably clear, nearly the whole of the Northumberland Islands were comprehended in the bearings from one or the other station. Two distant pieces of land in the N. W. by N., marked _k_ and _k1_, situate near the eastern c.u.mberland Islands of captain Cook, were also distinguished; but to the north-east, where I expected to see a continuation of the reefs discovered by captain Campbell of the brig Deptford, in 1797, neither reef nor island was visible.
SAt.u.r.dAY 2 OCTOBER 1802
On the 2nd of October, Mr. Brown accompanied me to No. 1, the southernmost of the Percy Isles, which is near five miles long, and the second of the group in magnitude. Fresh water was found in ponds near the sh.o.r.e, and there were cl.u.s.ters of pine trees; but in general, this island is inferior to No. 2, both in soil and productions. Of the two peaked hills upon it, the south-easternmost is highest; but being craggy and difficult to be ascended, my bearings were taken from the western hill.
In returning to the ship in the evening, we pa.s.sed between No. 6 and the east side of No. 2, and round the north end of the latter island, in order to see the form of its coasts: the water was deep, and there appeared to be no hidden dangers.
SUNDAY 3 OCTOBER 1802
On the 3rd, Mr. Bauer, the natural-history painter, went with me to the northern Percy Isles, upon each of which is a hill somewhat peaked; but that on No. 3 is much the most so, and the highest; and being thickly covered with pine trees, is called _Pine Peak_: it lies in 21 31" south and 150 14" east. My princ.i.p.al object was to take angles for the survey; and not being able to ascend Pine Peak, from its great acclivity, we went onward to the two smaller islands No. 4; and from the top of the easternmost, a third c.u.mberland Island, marked _k2_, was distinguished, and the following amongst many other bearings, were taken.
Percy Isle No. 3, Pine Peak, distant 2 miles, S 2 5" W.
The ship, at anchor under No. 2, S. 10 48 W.
Northumberland I., the 7th, station, S. 14 0 W.
Northumberland I., the peak marked "h", S. 67 35 W.
Northumberland I., the high, northmost, marked "i", N. 73 10 W.
c.u.mberland I., marked "k", centre, N. 36 0 W.
c.u.mberland I., marked "k2", centre, N. 42 50 W.
There is no shelter amongst the northern Percy Isles against east winds; but ships may pa.s.s between them, taking care to avoid a rock which lies one mile northward from the Pine Peak, and is dry at low water. Nothing was seen on these islands to merit more particular notice; and their forms and situations will be best learned from the chart.
On returning to the ship at nine in the evening, I found lieutenant Fowler had quitted the sh.o.r.e with his tents and people, the holds were completed with water, and both vessels ready for sea.
No. 2, the largest of the Percy Isles, is about thirteen miles in circ.u.mference; and in its greatest elevation perhaps a thousand feet. The stone is mostly of two kinds. A concreted ma.s.s of different substances, held together by a hard, dark-coloured cement, was the most abundant; I did not see either coral or pumice-stone in the composition, but it otherwise much resembled that of Aken"s Island in Shoal-water Bay, and still more a stratum seen at the north-west part of Long Island: it was found at the tops of the highest hills, as well as in the lower parts.
The second kind of stone is light, close-grained, and easily splits, but not in layers; it is of a yellowish colour, and probably argillaceous.
The surface of the island is either sandy or stony, or both, with a small proportion of vegetable soil intermixed. It is generally covered with gra.s.s and wood; and some of the vallies round the basin might be made to produce vegetables, especially one in which there was a small run, and several holes of fresh water. The princ.i.p.al wood is the _eucalyptus_, or gum tree, but it is not large; small cabbage palms grow in the gullies, and also a species of fig tree, which bears its fruit on the stem, instead of the ends of the branches; and pines are scattered in the most rocky places.
No inhabitants were seen upon any of the islands, but there were deserted fire places upon all. The Indians probably come over from the main land at certain times, to take turtle, in which they must be much more dexterous than we were; for although many turtle were seen in the water, and we watched the beaches at night, not one was caught. There are no kangaroos upon the Percy Isles; nor did we see any useful birds. The large bats or vampyres, common to this country, and called flying-foxes at Port Jackson, were often found hanging by the claws, with their heads downward, under the shady tops of the palm trees; and one solitary eel of a good size, was caught on clearing out the hole where our water casks had been first intended to be filled.
Pines, fresh water, and fish will be some inducement to visit the Percy Isles; as perhaps may be the hump-backed whales, of which a considerable number was seen in the vicinity. The best and most convenient anchorage, and indeed the only one to be recommended, is that where the Investigator lay, directly off the basin; in mid-channel between No. 2 and the western pine islets. It is sheltered at fourteen points to the eastward, and three towards the west; and there being a clear pa.s.sage out, both to the north and south, no danger is to be apprehended: the bottom, however, does not hold very well.
A wet dock might be made of the basin without other trouble or expense than a little deepening of the narrow entrance, and throwing a pair of gates across; and were the mud to be cleared out, the basin would contain fifteen or twenty sail of merchant ships with great ease.
The flood _tide_ came from the north and the ebb from the south, past the anchorage; but on the outside, they run south-west and north-east. It is not extraordinary that the rise and fall by the sh.o.r.e did not exactly coincide with the swinging of the ship; but that the time of high water should differ three hours, and the rise twenty feet from Broad Sound, is remarkable. According to Mr. Fowler"s observations in the basin, it was high water there _eight hours after_ the moon"s pa.s.sage; and the rise at the neaps and springs appeared to be from eight to twelve feet.
Three meridian observations to the north, taken by lieutenant Flinders, gave the _lat.i.tude_ of our anchorage, 21 39" 31" S.
_Longitude_, according to the position of Upper Head and the survey from thence, 150 12" E.
_Variation_ of the needle, observed on the low south-west point of No. 2, 8 28" E.
Three compa.s.ses on board the ship at anchor, gave 5 34" when the head was east, or corrected to the meridian, 8 4" E.
Upon the different elevated places whence bearings were taken, the variation differed from 7 30" to 9 30" east.
MONDAY 4 OCTOBER 1802
Early in the morning of the 4th, we got under way, with the Lady Nelson in company, to proceed on our voyage to Torres" Strait and the Gulph of Carpentaria. The wind was at E. by N., and we kept close up to weather the northern Percy Isles; for I had a desire to fall in with the reefs laid down by Mr. Campbell, three-quarters of a degree to the eastward, in lat.i.tude 21; and to ascertain their termination to the north-westward.
[EAST COAST. BARRIER REEFS.]
The tide prevented us from weathering the islands till three in the afternoon; we then pa.s.sed between No. 4 and some rocks lying two miles to the north-east, with 33 fathoms water. During the night we tacked every two hours, working to the eastward, in from 30 to 36 fathoms; and at daylight [TUESDAY 5 OCTOBER 1802], my station on the eastern isle No. 4 bore N. 89 W., four leagues. Nothing was seen in the offing, but in stretching to the N. N. E, reefs were discovered from the mast head a little before noon; and after the observation for the lat.i.tude was taken, I set one bearing East to E. by S., two leagues, and another N. 14 W. to 29 E., four or five miles. Our situation was in 21 15 2/3" south, and longitude from the bearing of the Pine Peak, 150 34" east.