A Voyage to Terra Australis/Volume 2/Book 2/Chapter 11
CHAPTER XI.
On completing the first portion of the voyage, I entered into an explanation of the winds and currents which had been found to prevail upon the south coast of Terra Australis; and to obtain greater perspicuity and connection, I there anticipated upon the second portion so far as those subjects required. This plan of assembling at the end of each book such general observations upon the coast immediately before examined as could not enter conveniently into the narrative, seeming liable to no material objection, I shall follow it here; and conclude this second part of the voyage with a statement of the winds and currents which appear to prevail most generally along the East and North Coasts; adding thereto such remarks, more particularly on Torres' Strait, as may tend to the safety of navigation. This statement will include the information gained in a subsequent passage, for the reasons which influenced me in the former account; and the reader must not be surprised, should he remark hereafter that I did not, in that passage, follow very closely the directions here given; for besides that my information was then possessed only in part, the directions are intended, not for vessels seeking dangers, which was partly my object, but for those desirous only of navigating these distant shores with expedition and safety.
The East Coast, with respect to winds and currents, requires (Atlas,
Plate I.)a division, the part beyond the tropic of Capricorn being placed under different, and almost opposite circumstances, to that within, or close to it.
From Cape Howe, where the South Coast terminates and the East commences, to Sandy Cape, within a degree of the tropic, the south-east trade most generally prevails in the summer season, from the beginning of October to the end of April; and produces sea and land breezes near the shore, with fine weather. There are however many occasional intermissions, especially in the southern parts, wherein gales from South or S.W., and strong breezes between North and N.E., bring heavy rain, with thunder and lightning; but these are usually of short duration. A sultry land wind from the N.W., in the summer, is almost certainly followed by a sudden gust from between S.E. and S.S.W., against which a ship near the coast should be particularly guarded; I have seen the thermometer descend at Port Jackson, on one of these occasions, from 100° to 64° in less than half an hour.
In the winter season, from May to September, the western winds are most prevalent, and generally accompanied with fine weather; the gales then blow from the eastward, between north-east and south, and bring rain with them; indeed there is no settled weather in the winter, with any winds from the sea, and even between north-west and north there is frequent rain, though the wind be usually light in those quarters. It is however to be understood, that the sea and land breezes in the summer are more regular near the tropic; and that the winter winds partake more of the south-east trade than they do from latitude 30° to Cape Howe.
It is a fact difficult to be reconciled, that whilst the most prevailing winds blow from S.E. in summer, and S.W. in winter, upon this extra-tropical part of the East Coast, the current should almost constantly set to the south; at a rate which sometimes reaches two miles an hour. Its greatest strength is exerted near to the points which project most beyond the general line of the coast; but the usual limits of its force may be reckoned at from four, to twenty leagues from the land. Further out, there seems to be no constancy in the current; and close in with the shore, especially in the bights, there is commonly an eddy setting to the northward, from a quarter, to one mile an hour. It is in the most southern parts that the current runs strongest, and towards Cape Howe it takes a direction to the eastward of south; whereas in other places, it usually follows the line of the coast.
This exposition of the winds and currents beyond the tropic, points out the advantage of keeping at not more than three or four leagues from the land, when sailing northward and intending to touch on the coast; but in the winter season this must be done with caution, because gales then often blow from the eastward. A marine barometer will here be of signal advantage. If the weather be tolerably fine, and the mercury do not stand above 30 inches, there is no probability of danger; but when the mercury much exceeds this elevation and the weather is becoming thick, a gale is to be apprehended; and a ship should immediately steer off, until it is seen how far the wind veers to blow dead on the coast. With respect to a rise and fall in the marine barometer, it may be taken as a general rule upon this East Coast, that a rise denotes either a fresher wind in the quarter where it then may be, or that it will veer more to seaward; and a fall denotes less wind or a breeze more off the land; moreover, the mercury rises highest with a south-east, and falls lowest with a north-west wind; and north-east and south-west are points of mean elevation.
The shelter for ships which may be caught so suddenly as not to be able to clear the land, are these: Two-fold Bay, for vessels of four-hundred tons and under; Jervis and Botany Bays, Port Jackson, and Broken Bay; Port Hunter for brigs and small craft; Port Stephens; Shoal Bay for vessels not exceeding fifty tons; Glass-house Bay; and lastly Hervey's Bay, by going round Break-sea Spit. All these places will be found in Plates VI, VIII, IX, and X, of the Atlas, with particular plans of the entrances to some of them. Directions for Port Jackson, and Botany and Broken Bays are given by captain Hunter in his voyage; and they may be found in Horsburgh's East-India Directory, Part II, p. 465–468. Two-fold Bay is described in the Introduction to this voyage, and mention made of Jervis, Shoal, Glass-house, and Hervey's Bays.
A ship sailing along this coast to the southward, should not, to have the advantage of the current, come nearer than five or six leagues unless to the projecting points; and if the distance were doubled, so as to have the land just in sight, an advantage would be found in it; and such an offing obviates the danger of the gales.
Whilst western winds prevail on the southern parts of the East Coast, the south-east trade blows with most regularity within, and close to the tropic, producing sea and land breezes near the shore, and serenity in the atmosphere; and the further we go northward the longer does this fine weather last, till, near Cape York, it commences with the month of April, probably even March, and extends to the middle or end of November. How the winds blow from November to April, I have no experience; but there is great reason to believe that they come from the northward, and make the wet season here, whilst dry weather prevails beyond the tropic. In Broad Sound and Shoal-water Bay we had more northern winds than any other, in the month of September; but these appeared to be altogether local, caused by the peculiar formation of the coast; for they did not bring any rain, though it was evidently near the end of the dry season, and we found the south-east trade wind before losing sight of the land.
The North Coast appears to have the same winds, with a little exception, as the tropical part of the East Coast. From March or April to November, the south-east trade prevails; often veering, however, to east, and even north-east, and producing fine weather, with sea and land breezes near the shore. At the head of the Gulph of Carpentaria, the north-west monsoon began to blow at the end of November; but further westward, at the northern Van Diemen's Land, I apprehend it will set in at the beginning of that month, and continue till near the end of March. This is the season of heavy rains, thunder, and lightning, and should seem, from our experience, to be the sickly time of the year.
It is thought to be a general rule, that a monsoon blowing directly in from the sea, produces rain, and from off the land, fine weather, with sea and land breezes; this I found exemplified on the west side of the Gulph of Carpentaria, where the rainy north-west monsoon, which then came off the land, brought fine weather: the rain came with eastern winds, which set in occasionally and blew strong for two or three days together. It seems even possible; that what may be the dry season on the North Coast in general, may be the most rainy on the west side of the Gulph; but of this I have doubts.
According to Dampier, the winds and seasons on the north-west coast of Terra Australis are nearly the same as above mentioned upon the North Coast; but he found the sea and land breezes, during the south-east monsoon, to blow with much greater strength.
In speaking of the currents, I return to the tropical part of the East Coast. Within the Barrier Reefs, it is not the current, for there is almost none, but the tides which demand attention; and these, so far as they came under my observation, have been already described, and are marked on the charts. At a distance from the barrier there is a current of some strength, at least during the prevalence of south-east winds; but instead of setting southward, as I have described it to do from Sandy Cape to Cape Howe, the current follows the direction of the trade wind, and sets to the north-west, with some variation on either side, at the rate of half a mile, and from thence to one mile an hour. This I found to continue amongst the reefs of Torres' Strait, nearly as far as Murray's Islands; but from thence onward through the strait, its direction in October was nearly west, something more than half a mile; and so continued across the Gulph of Carpentaria to Cape Arnhem, with a little inclination toward the south.
Along the north coast of Terra Australis, the current seems to run as the wind blows. In March, before the south-east monsoon was regularly set in, I found no determinate current until the end of the month, when Timor was in sight, and if then set westward, three quarters of a mile an hour; but in the November following, I carried it all the way from Cape Arnhem, as captain Bligh had done from Torres' Strait in September 1792; the rate being from half a mile to one mile and a quarter in the hour.
The navigation along the tropical part of the East Coast, within the Barrier Reefs, is not likely to be soon followed, any more than that round the shores of the Gulph of Carpentaria; nor does much remain to be said upon them, beyond what will be found in this Book II, and in the charts; and in speaking of the outer navigation, my remarks will be more perspicuous and useful if I accompany a ship from Port Jackson, through Torres' Strait; pointing out the courses to be steered, and the precautions to be taken for avoiding the dangers. It is supposed that the ship has a time keeper, whose rate of going and error from mean Greenwich time have been found at Sydney Cove, taking its longitude at 151° 11′ 49″ east; and that the commander is not one who feels alarm at the mere sight of breakers; without a time keeper I scarcely dare recommend a ship to go through Torres' Strait; and from timidity in the commander, perhaps more danger is to be anticipated than from rashness. The best season for sailing is June or July; and it must not be earlier than March, nor later than the end of September.
On quitting Port Jackson, the course to be steered is N.E. by E. by compass, to longitude about 155½°, when the land will be fifty leagues off; then North, also by compass, as far as latitude 24°. Thus far no danger lies in the way; but there is then the Cato's Bank,(Atlas,
Plate X.) a dry sand frequented by birds and surrounded with a reef, and further northward is Wreck Reef, both discovered in the future part of this voyage. Wreck Reef consists of six distinct patches of coral, extending twenty miles east and west; upon four of them there are dry banks, also frequented by birds, and the easternmost bank is covered with wiry grass and some shrubs, and is called Bird Islet. Their situations are these:
Cato's Bank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
23° | 6′ | south, | 155° | 23′ east |
Bird Islet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
22 | 11½ | 155 | 27 |
The bearing and distance of these dangers must be successively worked, and a course steered so as to leave them half a degree to the westward; but for fear of an error in the time keeper the latitude 23° 20′ should not be passed in the night. It is better to make short tacks till daylight, than to heave to; and allowance should be made for a probable current of one mile an hour to the north-west. A good look-out must be constantly kept; and a confidential officer should now go to the mast-head every two hours in the day and to the fore yard at night, to listen as well as look; for in dark nights the breakers may often be heard before they can be seen. It will not be amiss, if the time of the day be favourable, to make Bird Islet, which is well settled, in order to see how the longitude by time keeper agrees; and should it err, the difference, or more, must be added to, or subtracted from its future longitudes; for it is most probable that the error will continue to augment the same way, more especially if the time keeper be a good one.
(Atl. Pl. I.)Having passed Wreck Reef, there are no other known dangers near the route for Torres' Strait, till we come to Diana's Bank; but as others may exist, it will be prudent to lie to, or preferably to make short tacks in the night, during the rest of the passage to the Strait. In light nights, however, and moderate weather, there would be not much risk in closely following the Cumberland's track, carrying no more sail than will allow of the ship being conveniently hauled to the wind; but if an unusual number of boobies and gannets be seen in the evening, there is strong suspicion of a bank and reef being near; and the direction which the birds take, if they all go one way as is usual in an evening, will nearly show its bearing. The longitude of Diana's Bank, according to M. de Bougainville, is 151° 19′ from Greenwich; but his longitude at the New Hebrides, some days before, was 54′ too far east, according to captain Cook; and it is therefore most probable, that
Diana's Bank lies in 15° 41′ south, 150° 25′ east.
I should steer, after passing Wreck Reef, so as to go a full degree to the east of this position; and having so done, the next object of attention is the Eastern Fields, reefs which lie a degree(Atlas,
Plate XIII.) from those where Torres' Strait may be said to commence. The position to be worked is,
Eastern Fields, north-east end, 10° 2′ south, 145° 45′ east;
and from this I would pass half a degree to the eastward. But if the Strait should be attempted without a time keeper, it will be advisable for a ship to make that part of New Guinea lying in about 10° south and 147¼° east, which may be seen as far as twelve or fifteen leagues in clear weather; and having corrected the dead-reckoning longitude by this land, to allow afterwards eighteen miles a day for a current setting to the W.N.W. The best latitude for passing the Eastern Fields, is 9° 45′ to 50′, steering a W. by S. course, by compass; and it will afterwards be proper, so long as there is daylight and no reefs seen, to carry all sail for the Pandora's Entrance, which is the best opening yet known to the Strait. It is formed by reefs, and is eleven or twelve miles wide, and lies,
Pandora's Entrance, the middle, in 9° 54′ S., 144° 42′ E.;
and it is very possible, if the Eastern Fields be passed in the morning, to get through without seeing the breakers, and obtain a sight of Murray's Islands before dark. But it is most probable that reefs will be first met with; and should the latitude of the ship be then uncertain, even to 5′, the wind must be hauled until an observation can be had, for it is by the latitude alone that the first reefs can be distinguished one from the other.
The reefs being in sight and the latitude known, a ship will steer for the Pandora's Entrance, if she can fetch it; but if too much to the north, she may pass round the north end of Portlock's Reef, and haul up S.W. for Murray's Islands, which are visible eight or ten leagues from the deck in fine weather. (See View No. 10 in Plate XVIII. of the Atlas.) It is best to approach these islands from the N.E. by N., following the Investigator's track, and to anchor the first night on the north side of the largest island, or otherwise under the reefs which lie to the north-east; but if neither can be reached before dark, haul to the wind and make short trips till daylight, in the space between these reefs and Portlock's Reef.
Murray's Islands should not be passed, or quitted if the ship have anchored there, later than ten or eleven o'clock in the morning; because the sun will be getting a-head and obscure the sight before another good anchorage can be secured. On passing the islands, keep the reef which lies five miles to the north about a mile on the starbord hand, steering W. ½ S. by compass, with a boat a-head; for in this part there are many tide ripplings scarcely to be distinguished from the reefs. Having passed the ripplings, haul a point more to the southward; and after having run eight or ten miles, from the time that the largest island bore south, there will be very few reefs to the northward, and Darnley's Island will be seen. On the larbord hand there will be a great mass of reefs; and these it is necessary to follow at the distance of two or three miles, steering mostly W.S.W., and gradually more southward as they are found to trend. Some small patches will occasionally be met with; but having the boat to go a-head, and the commander, or a careful officer looking out aloft, the Investigator's track between them may be safely followed. The leading mark in all this part of the course, is the line of the great south-eastern reefs; and the situation of the ship may be known at any time, by laying down cross bearings of Murray's and Darnley's Islands on the chart, allowing, if the ship's head be westward and the compass on the top of the binnacle, 5° of east variation.
Several low, woody isles will come in sight a-head, or on the starbord bow; and before reaching the end of the south-eastern reefs, Half-way Island, which is the southernmost of them, will be seen to the south-west; and here I would recommend the ship to anchor for the night. If this island can be passed, however, before three in the afternoon, and the sun do not obscure the sight, she may push on south-westward till an hour before sunset; and anchor under the lee of any of those sand banks which lie in the route, the ground being better here than in the eastern part of the Strait.
From Half-way Island, continue to follow the Investigator's track, steering S.W. to S.W. by W. by compass, as the small reefs and banks will allow; and here there is no necessity for a boat to be kept a-head. The flat top of one of the York Isles, called Mount Adolphus by captain Bligh, will be the first high land seen, and afterwards Mount Ernest; the cross bearings of which will show the situation on the chart, until the Double Isle, which makes as two small hummocks, comes in sight. Steer then for Double Isle, pass on the north side, and haul south-westward for Wednesday Island, which will be three leagues distant. Pass it also on the north side, about one mile, and the same by Hammond's Island, which lies next to it. There will be an extensive reef on the starbord hand, but the smallest distance between it and the islands is above two miles; and a W.S.W. course by compass, will lead fair through the passage, with soundings from 9 to 6 fathoms. Booby Isle will presently be seen a-head, appearing at first like a white sand bank; it may be passed within a mile or two on either side, and is the last of the dangers, if it can be classed under them, of Torres' Strait. A ship should afterwards steer, by compass, W. by S. thirty or forty miles; and the course may then be directed for any part of the world.
In case the approach of night, or any other circumstance should make it desirable, shelter may be had under the Prince of Wales' Islands, or under Booby Isle; and if a boat be sent on shore at dusk to Booby Isle, many birds, and perhaps some turtle may be procured.
This passage through Torres' Strait will occupy from three to five days, according to the freshness of the south-east trade, and the degree of caution which a commander may see necessary to employ.[1] He will, of course, sound continually, though it have not been specified; and keep a boat a-head with sounding signals, from the time of passing Murray's Isles till Half-way Island is in sight, and where-ever else there appears to him a necessity. Should he miss the Investigator's track in any part, which is very possible, there is no occasion for alarm; most, if not all the inner reefs have deep channels through them at every four or five miles, and by these he may regain the track, with the assistance of his boat.
The following precautions must not be neglected: a strict and constant look-out at the mast head, by the commander or his most confidential officer, all the time that the ship is amongst the reefs;—not to pass Murray's Islands without seeing them, since they are the leading mark for getting into the proper track;—and on anchoring there, or at any other inhabited island, a strict watch must be kept on the natives, who will come off in canoes to barter a few cocoa-nuts, plantains, and their arms, for hatchets and other iron ware. No boat should be sent to an island where there are inhabitants; but if distress make it necessary, two or three should go together, well armed; for they will certainly be attacked, if the Indians have been able to lay a plan and collect their strength. A British seaman will, at the same time, studiously avoid all cause of quarrel with these poor misguided people, and not fire upon them but where self-defence makes it indispensable.
Most of the dry sands and the uninhabited islands in the Strait appear to be frequented by turtle; and in the month of August, September, or later, it is probable some might be taken by landing a party of men, who should silently watch for their coming on shore at dusk. I do not know the kind of turtle most common in the Strait; at Booby Isle they were hawkes-bill, which furnish the finest tortoise shell, but are small and not the best for food.
The advantage in point of time, which this route presents to a ship bound from the Great Ocean to India, or to the Cape of Good Hope, will be best seen by a statement of two passages made at the same season; the one by Torres' Strait, the other round New Guinea.
I sailed from Port Jackson in company with the Bridgewater, an extra East-Indiaman; and we made Wreck Reef in eight days. From thence the Bridgewater steered round Louisiade, through Bougainville's Strait, Dampier's Strait, Pitt's Passage, and the Strait of Salayer; and arrived at Batavia in eighty-eight days. I left Wreck Reef some time afterward, in a small schooner of twenty-nine tons; took ten days to reach Torres' Strait, three to pass through it, seventeen to reach Coepang Bay, and ten more to pass the longitude of Java Head. Adding to these the eight days to Wreck Reef, the passage from Port Jackson to Java Head was forty-eight days, including various deviations and stoppages for surveying; and it was principally made in a vessel which sailed no more than four or five knots, when the Bridgewater would have gone six or eight. The difference, nevertheless, in favour of Torres' Strait, was forty days; so that it seems within bounds to say, that in going from Port Jackson to India or the Cape of Good Hope, it offers an advantage over the northern route of six weeks; and of four weeks in going from the more eastern parts of the Great Ocean. In point of safety, I know not whether Torres' Strait have not also the advantage; for although it be certainly more dangerous than any one of the eastern passages, it is doubtful whether it be more so than a four or six weeks extra navigation amongst the straits and islands to the east and north of New Guinea, where some new shoal, bank, or island is discovered by every vessel going that way. For myself, I should not hesitate to prefer Torres' Strait, were it only on this account; considering the long continuance of the danger in one case, as being more than a counterbalance to the superior degree of it in the other.
With respect to a passage through Torres' Strait in the opposite direction,—from the Indian Sea to the Great Ocean, it has not, to my knowledge, been attempted; and I have some doubt of its practicability. A ship would have an advantage in entering the strait by its least dangerous side; but as the passage could be made only in December, January, or February, the rainy squally weather which probably will then prevail, would augment the danger from the reefs ten fold. The experiment is therefore too hazardous for any except a ship on discovery; whose business it is to encounter, and even to seek danger, when it may produce any important benefit to geography and navigation.
- ↑ The most expeditious passage known to have been made through the Strait, previously to the Investigator, was that of captains Bligh and Portlock, in nineteen days; the account of which, as also that of Messrs. Bampton and Alt in the Introduction, page xix to xlv, a commander should previously read with the chart before him; and if he do the same with the passage of the Investigator, in Chap. V. of this Book II., and that of the Cumberland in Chap. III. following, he will have a tolerably correct notion of the dangers in Torres' Strait, and of the advantage in pursuing the route above described.