# A Voyage to Terra Australis/Volume 1/Book 1/Chapter 11

CHAPTER XI.
Before entering upon the second part of the voyage, it seems proper to give an account of the winds and currents which prevailed upon the South Coast; and to add thereto such other general information as may be useful in rendering the navigation more safe and expeditious, both along the coast and through Bass' Strait.
The rate and direction of the currents here described, are deduced from the daily positions of the ship by astronomical observation, compared with those given by a log kept in the common way, but with somewhat more than common attention. In the observations, however, there may be some errors, and a log cannot be depended upon nearer than to five miles in the distance, and half a point in the course for the twenty-four hours; and consequently this account of the currents must be taken as subject to the sum, or to the difference of the errors in the observations and log; though it is probable they may have been diminished by taking the medium of several days, which has always been done where it was possible.
Besides the difficulty there is in obtaining the exact rate and direction of a current, it is known that a continuance of the wind in any particular quarter may so far change its rate of moving, and even its direction, that at another time it may be found materially different in both. Of the probability of these changes the commander of a ship must form his own judgment, from the winds he ​may have previously experienced; and he will consider what is here said upon both winds and currents, as calculated and intended to give him a general notion, and no more, of what may usually be expected upon the South Coast.
(Atlas, Plate I.)Several days before making Cape Leeuwin, I experienced a current setting to the northward, at the rate of twenty-seven miles per day; but at the mean distance of forty leagues, west-south-west from the cape, the current ran north-east, twenty-two miles; and when the ship got in with the South Coast, I found it setting N. 70° E., at the average rate of twenty-seven miles per day: this was in the month of December. On approaching Cape Leeuwin in May, from the north-westward, the current for five days was ten miles to the east; but at forty leagues from the cape, it ran N. 35° E. fifteen miles; and from the meridian of the cape to past King George's Sound, the current set east, twenty-seven miles per day, nearly as it had before done in December. Captain Vancouver and admiral D'Entrecasteaux do not speak very explicitly as to the currents; but it may be gathered from both, that they also experienced a set to the eastward along this part of the South Coast.
The winds seem to blow pretty generally from the westward at Cape Leeuwin. In the summer time, they vary from north-west in the night, to south-west in the latter part of the day, though not regularly; and in the winter season this variation does not seem to take place. A long swell of the sea, called ground swell to distinguish it from the lesser, variable one of the surface, appears to come at all times from the south-westward, which indicates that the strongest and most-durable winds blow from that quarter; and this was partly confirmed by our experience, for whenever it blew hard, the wind was at, or near to south-west.
It is from the superior strength and apparent prevalence of this wind, that the currents in the neighbourhood of Cape Leeuwin may be explained. The sea being driven in from the south-west, and meeting with the cape, will necessarily be divided by it, and ​form two currents, which will follow the directions of the land; one branch will run northward, along the west coast of Terra Australis, and the other eastward along the South Coast: our present business is to follow the latter current.
If a line be drawn from the south-western extremity of New Holland, to King's Island in Bass' Strait, it will show where the current may be expected to run strongest; though it will not be equally strong at those parts of the line which are distant from the land, as at those in its immediate vicinity. In drawing another line, from the north-eastern isles of the Archipelago of the Recherche to Cape Northumberland, we shall have what will commonly be the northern boundary of the current; for within this line the water does not seem to run in any constant direction, but is moved according as the wind may happen to blow. This was found by admiral D'Entrecasteaux; and is conformable to my experience, as I shall now explain.
It has been said, that the eastwardly current was found in May and December to run twenty-seven miles per day, from Cape Leeuwin past King George's Sound. From thence to a little beyond the Archipelago of the Recherche, keeping in with the shore, I found it to set north-east thirteen miles; and at a distance from the coast, it ran north-east-by-east sixteen miles per day, the wind being more from the south than from the northward in both cases.
In coasting from the Archipelago, all round the Great Bight and as far south-eastward as to Cape Northumberland, I had no determinate current; it generally followed the impulsion given to it by the winds, and was inconsiderable. From the middle of January to the middle of April, the winds were most prevalent from south-south-east to east-north-east; coming more from the land at night, and from the sea in the day time. They seldom had any strength; whereas the winds which occasionally blew from the westward were fresh, and sometimes became gales, veering in that case, invariably to the south-west.
​On reaching Cape Northumberland I again found the eastwardly current; and from thence into Bass' Strait it ran N. 80° E., at the rate of twelve miles a day, the wind blowing strong from the south-westward in the latter part of the time.
In a subsequent run across the Great Bight in May, from the Archipelago nearly direct for Bass' Strait, the current set upon the average, N. 39° E. fourteen miles a day; appearing to be much influenced in its northern direction by the winds blowing strong from the southward. Mr. Dalrymple, in reasoning from the analogy of southern Africa, expected that the winds upon this coast would be found to blow from the northward, or off the shore, in the winter time, and this might possibly be the case if close in with the land; but at a distance from it, as just observed, the winds were from the southward.
Such an accumulation of water forcing itself through Bass' Strait, would naturally lead to the expectation of finding a strong current there, setting to the east; but on the contrary, the set in common cases was found to be rather in the opposite direction, the current appearing to be predominated by the tides, whose superior strength forced it below the surface. The flood comes from the eastward; and after making high water at Furneaux's Isles, passes on to Hunter's and King's Islands, where it meets another flood from the southward; and the high water then made seems to be nearly at the time that it is low water at Furneaux's Isles. Another flood is then coming from the east, and so on; whence a ship going eastward through the Strait, will have more tide meeting than setting after her, and be commonly astern of her reckoning. This applies more especially to the middle of the strait, and is what I there found with winds blowing across it; but the bight on the north side, between Cape Otway and Wilson's Promontory, seems to be an exception, and in fact, it lies out of the direct set of the tides. In running from Port Phillip to the Promontory I was set S. 73° E., thirty-five ​miles in the day; but it then blew a gale from the west and south-westward.
Although the eastwardly current be not commonly found at the surface in Bass' Strait, it is not lost. Navigators find it running with considerable strength, when passing the strait two or three degrees to the east of Furneaux's Islands; and it was this current so found, which led admiral Hunter to the first opinion of the existence of an opening between New South Wales and Van Diemen's Land.
Every thing in Bass' Strait bespeaks the strongest winds to come from the south-west; and there is reason to believe that during nine months of the year, it generally blows from some point in the western quarter. In January, February, and March, eastern winds with fine weather seem to be not uncommon; but there is no dependence to be had on them at any other season. At the eastern side of the strait and of Van Diemen's Land, it is not unusual to meet a north-east or north wind, though it seldom blows strong. The gales usually come from between south-west and south-east, and most frequently from the latter direction; which renders it hazardous to approach the coast between Cape Howe and Wilson's Promontory.
Thus, speaking generally of the south coast of Terra Australis, it may be considered that during the six or eight winter months, the winds blow almost constantly from some western point; and that gales of wind at south-west are frequent. The progress of the gales is usually this: the barometer falls to 29½ inches, or lower, and the wind rises from the north-westward with thick weather, and commonly with rain; it veers gradually to the west, increasing in strength, and the weather begins to clear up so soon as it has got to the southward of that point; at south-west the gale blows hardest, and the barometer rises; and by the time the wind gets to south or south-south-east, it becomes moderate, the weather is fine, and the barometer above 30 inches. Sometimes the wind may return back to west, or something northward, with a fall in the ​mercury, and diminish in strength, or die away; but the gale is not over, although a cessation of a day or two may take place. In some cases, the wind flies round suddenly from north-west to south-west; and the rainy, thick weather then continues a longer time.
Such is the usual course of the gales along the South Coast and in Bass' Strait; but on the east side of the strait the winds partake of the nature of those on the East Coast, where the gale often blows hardest between south and south-east, and is accompanied with thick weather, and frequently with heavy rain.
In the four or five summer months, the south-east and east winds appear to be most prevalent all round the Great Bight; but even there, the western winds sometimes blow at that time, and usually with considerable strength. Thus I had a strong south-west wind in the middle of February, near the Investigator's Group, and a gale from the same quarter in March, at the entrance of Spencer's Gulph; which last was felt still more severely in Bass' Strait by captain Baudin. At the two extremities of the coast, that is, in the strait and near King George's Sound, the winds blow sometimes from the west and sometimes from the eastward, in the summer; but the strongest winds are from the south-west.
It will hence appear, that the summer is alone the proper time for a ship to come upon, and still more so for exploring the south coast of Terra Australis; whether she proceed along it from west to east, as I did in the Investigator, or from east to west, as captain Baudin, seems to be almost a matter of indifference. From Cape Leeuwin to the end of the Archipelago of the Recherche, and from Cape Northumberland to Bass' Strait, it is perhaps most advantageous to proceed eastward, on account of the current; but in the intermediate and more considerable part of the coast, a western route is certainly preferable. It has also this general advantage, that the winds which are fair for running along the coast are those that blow moderately, and are accompanied with fine weather, most ​proper for making a survey; whereas those favourable to the opposite route frequently blow strong, and render it dangerous to keep in with the land. As to making a survey of the South Coast in the winter season, which had been judged from theoretical analogy to be the most proper time, it appears to be not only a dangerous experiment, but also one from which very little accuracy of investigation could be expected; and with as much ardour as most men for such pursuits, I should very unwillingly undertake the task.
These observations upon the danger of sailing along the South Coast in the winter season, are not meant to apply to the commander of a ship desirous of going eastward through Bass' Strait, and of seeing no more of the land than is necessary to assure his situation. The strait may be passed without more than very common danger, at any time of the year, provided that the navigator be certain of his latitude before approaching the longitude of 143½°; he should not, however, enter the strait in the night, unless he have previously seen the land, or be certain both of latitude and longitude. The parallel of 39°, or 39° 20′, according as the wind may incline, is the best for taking a ship between King's Island and Cape Otway; and a sight of either, or preferably of both, will point out his position on the chart. The sole danger to be apprehended here, is the Harbinger's Reefs, two patches lying nearly two leagues out from the north end of King's Island; but are so far separated from it, and from each other, as to leave practicable passages between them, where the shoalest water found by the Cumberland schooner was 9 fathoms.
(Atlas, Plate VI.)When the position of the ship at the entrance of the strait is ascertained, a course should be shaped for Curtis' Island, which will be visible ten or eleven leagues from the deck in fine weather; and as the distance is between forty and fifty leagues, and nothing lies in the way, a part of it may be run in the night, with a good look-out. I would afterwards pass on the south side of Kent's Groups, at not a greater distance from the largest than two leagues; and then steer ​east-north-east by compass, if nearly before the wind, or on either side of that course as the wind may incline; but taking care not to approach the northern Long Beach.
In case of meeting with a continuance of foul winds, the most convenient places in the strait for anchorage, when going eastward, are these:
1st. Under the north-west end of King's Island, near the New Year's Isles. Of this anchorage I know only, besides what is given in the chart, that the brig Harrington there rode out a gale from south-west, the heavy sea being broken off by the New Year's Isles; and the shelter from eastern winds must certainly be much more complete.
2nd. Port Phillip; anchoring just within the entrance, on the south side. When a fair wind comes, a ship can get out of the port by means of the strong tides.
3rd. Hunter's Isles, between Three-hummock and Barren Islands; taking care not to anchor too close to the weather shore, lest the wind change suddenly.
4th. The bight between Wilson's Promontory and Cape Liptrap, in case of necessity; but I would not recommend this place, it being very dangerous should the wind shift to south-west.
5th. Kent's large Group for brigs and lesser vessels; in one of the small sandy coves under the eastern island.
6th. Furneaux's Isles, between Clarke's and Preservation Islands. If the ship be not able to weather Clarke's Island, and pass out to the south-eastward when the fair wind comes, she may run through Armstrong's Channel, with a boat a-head and a good look-out.
This is all that it seems necessary to say for the information of a commander desirous of going eastward through Bass' Strait; and with the chart in the Atlas, (Plate VI.), it is all that a man of moderate experience and judgment will desire. I have not mentioned the entrance to the strait between King's Island and Hunter's Isles, thinking it not to be recommendable; both on account of Reid's Rocks, ​which lie in the passage, and whose position is not well ascertained, and also because I am not satisfied that Hunter's Isles are placed in the chart at their true distance from King's Island: the difference of longitude is from an approximation only; but the error, if any, cannot exceed eight or ten miles, and is in excess. However, with daylight and a good look-out, the strait may be safely entered by this pass, at any time that a ship can carry sail upon a wind. I entered this way in the Investigator, during the night; but what a ship on discovery may do is not to be given as an example to others, whose sole objects are expedition and safety. The outlet by the pass called Banks' Strait, between Furneaux's Islands and Cape Portland, is perfectly safe; but is out of the way for a ship bound to Port Jackson.
It has been observed that the winds are commonly favourable for making a passage to the westward, through Bass' Strait and along the South Coast, in the months of January, February, and March. I have no personal experience of such a passage, further than through the strait, though it has lately been made several times; but to those who may be desirous of doing the same, and are strangers to these parts, the following observations may be acceptable.
The first remark is, that the three months when this passage is most easy to be made, are precisely those in which it is unsafe, if not impracticable to go through Torres' Strait; and the second, that it will generally be of no avail for a ship to be in Bass' Strait before the middle of December, and if it be the middle of January it will be preferable.
Ships coming from Port Jackson, or any where from the north-eastward, may take a departure from Cape Howe in 37° 30½′ south and 150° 5′ east; but from thence, they should not steer a course more westward than south-south-west by compass, until in latitude 39° 30′; on account of the danger to be apprehended from south-east winds upon the Long Beach. Having reached 39° 30′ they should steer a true west course, or west-by-south by compass, leaving ​the Sisters, the craggy islet, and a rock, on the larbord hand. The eastern island of Kent's large Group, which lies in 39° 30′ south, 147° 19′ east, and may be seen ten, or perhaps twelve leagues from the deck in fine weather, will come in sight a-head; and in passing three or four miles on the south side, the small western group will be seen, and is to be passed in the same way; as are Curtis' peaked Isles, which will then be in sight. From Curtis' Isles to the north end of King's Island, the course is nearly true west, and distance about forty-two leagues, with nothing in the way; but it is better to steer five or six leagues to the north of King's Island, if the winds permit. Should they hang to the westward of north, the course may be safely directed for Three-hummock Island; passing afterwards to the north or south of King's Island, as the winds may be most favourable.
In the case of foul winds, which, if the weather be thick or rainy, may be expected to fix at south-west and blow strong, there are many places where a ship may anchor, to wait a change; but the following appear to be the most convenient.
1st. Hamilton's Road, at the east end of Preservation Island.
2nd. On the south side of the largest Swan Isle, for small vessels, or under Isle Waterhouse.
3rd. Port Dalrymple.
4th. Various places amongst Hunter's Isles.
5th. Sea-elephant Bay, on the east side of King's Island, where there is fresh water; or under the north-east end of that island, if the wind be from south-west.
6th. Western Port, under Phillip Island; anchoring so soon as the ship is sheltered. A fair wind for going onward through the strait, will take a ship out of this port.
7th. Port Phillip.
(Atlas, Plate I.)After clearing Bass' Strait, I think it most advisable to keep at not more than ten or twenty leagues off the coast, from Cape Otway to Kanguroo Island; as the wind may there be expected ​more favourable, and the contrary current less strong than in steering a straight course toward Cape Leeuwin. But should the wind rise from the north-westward, with thick weather and a descent more than usually rapid in the marine barometer, a stretch offshore should immediately be made, to prepare for a south-west gale. A look-out must be kept for an island lying to the west-south-west of Cape Northumberland; it was seen by Mr. Turnbull, commander of the Britannia, south whaler, but the weather being thick, its situation was not well ascertained. According to the best information I could procure, this island lies in 38¼° south, and about 139½° or ¾ east longitude.
From Kanguroo Island, a straight course may be made for the southernmost part of the Archipelago of the Recherche; but should the winds come from the westward and not blow a gale, or be light and unsteady, I would steer more northward, nearer to the land, in the hope of having them more favourable. From the Archipelago to Cape Leeuwin it seems best to keep at a distance from the land, unless under the necessity of stopping in that neighbourhood; for the current runs strong near the shore, and with the advantage of an offing of twenty or thirty leagues, a ship may lie clear of the cape with a wind which might otherwise keep her beating for many days.
There appears to be no place of shelter against western gales, between Bass' Strait and Kanguroo Island; but there are then, besides various anchorages under that island, the bays and coves at the entrance of Spencer's Gulph; and further westward, Coffin's Bay, Petrel Bay in the island St. Francis, and Fowler's Bay near the head of the Great Bight. Afterwards come Goose-Island Bay, Thistle's Cove, and the lee of Observatory Island, all in the Archipelago of the Recherche; the cove cannot be entered in a gale, but when once secured in the south-west corner, a ship will be safe; the other two places afford very indifferent shelter from strong winds, and are indeed fit only for a temporary anchorage in moderate weather. Doubtful-Island Bay and King George's ​Sound afford complete shelter against western gales; but some little time would be lost in getting out of them, if a ship waited until an eastern wind set in. Some account of all these places will be found in the preceding pages of this volume; with the exception of Observatory Island, for which D'Entrecasteaux's voyage may be consulted.