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.