All this part of the coast is subject to the effects of mirage, by which its outline is at times very much distorted, but generally speaking it ceases with the strength of the breeze, and as the sun attains a little alt.i.tude. When the effects of mirage was observed in the morning, I noticed that the winds were much lighter throughout the day, than usual.
During this part of the year, the atmosphere is clear, with a cloudless sky, and the coast is exempted from the violent East-South-East squalls, that are of frequent occurrence, while the sun is in the southern hemisphere, and the land consequently very much heated.
Towards the latter end of August, and in September, the winds are not quite so regular, and there are occasional intervals of two or three days of westerly winds.
That part of the North-West coast between the North-West Cape, and the 116th degree of east longitude, seems to be subject to westerly winds at all times of the year. The prevailing southerly winds that blow along the west coast, appear to draw round the Cape, and follow the direction of the land. Between April and October (when the easterly monsoon is blowing to the northward) they are generally to the southward of west, or between that point and South-West, but during the westerly monsoon between West and North-West.
Upon getting to the westward of the North-West Cape, the wind becomes more southerly, and draws to the eastward of south as the distance from the land increases, and will be found varying between South-South-East and East-South-East, generally speaking as far south as the parallel of 30 degrees of south lat.i.tude, after which it is mostly to the westward of south, so that ships making a pa.s.sage to the southward, along the west coast of New Holland, will rarely be able to make any easting, before reaching that lat.i.tude, particularly during the summer months. In the winter a ship may occasionally make a quick pa.s.sage to the southward, if happening to be upon the coast during a northerly gale; and as all these gales are preceded by North-East winds, a sufficient offing may be gained to enable her to run on, when the wind gets to the southward of west.
ON THE NORTH COAST OF AUSTRALIA.
That part of the coast of New Holland from Cape York to Cape Van Diemen, and extending as far south as the parallel of 12 degrees south lat.i.tude, may be said to be within the limit of the east and west monsoons, as at a short distance from the coast, these periodical winds will be found to blow with great regularity.
Near the land, the easterly monsoon sets in between the 1st and middle of April, and the westerly monsoon in October, and sometimes not until November. At a distance from the land they are probably more regular, as the changes of the monsoons are said to take place about the first week in April and October.
In the month of July, we found the winds between b.o.o.by Island and Port Essington, fresh from the eastward, veering at times to East-South-East and occasionally to South-East but rarely to the northward of east. Close to the land these winds are not so constant, but take more the character of land and seabreezes, and the nights are mostly calm; this we found to be the case during part of the months of July and August, while at anchor in Port Essington. The general course of the winds during that period was as follows. A little before sunrise, a breeze sprang up from South or South-South-East which gradually became more easterly as the sun approached the meridian; sometimes in the middle of the day, it was light from the eastward, or calm, and at other times veered gradually to North-East, from which quarter there came a fresh seabreeze every afternoon; this breeze lasted until sunset, and at times later, but the nights were always calm.
We experienced similar winds between Melville Island and Port Essington, but being a short distance from the land, the nights were not calm, although the winds were very light.
During the easterly monsoon, it is difficult to get to the eastward, as at a few miles from the land the current is always running to the westward, and runs strong past the projecting points; but by contriving to be near the land at daylight, at which time the wind is always more southerly, something may be gained.
At Port Essington, the rainy season can scarcely be said to set in before the middle of November; there is then, squally, dirty weather, with rain from the westward and North-West, and at this season, there are at times heavy squalls from South-East accompanied by rain, thunder, and lightning.
In 1838, the westerly monsoon set in at Port Essington, in the first week in November; there had been no rain before that.
THE END.