APPENDIX.
WINDS AND WEATHER ON THE WESTERN AND NORTHERN COASTS OF AUSTRALIA.
BY COMMANDER J.C. WICKHAM, R.N.
The winds on the western coast of Australia, are, for the most part, from some southern point--chiefly between South-South-West and South-South-East.
During the summer, or from the early part of October to the beginning of April, they are almost constant from this quarter; but in the winter their regularity is broken in upon by occasional winds between north and west that at times blow with great violence, and are accompanied by heavy rain, and thick dirty weather.
Near the shore, land and seabreezes appear to be regular, the former generally dying away towards the middle of the day, after having reached as far as East from about South-East at sunrise; then follows a short interval of calm, after which, the seabreeze sets in, mostly at South-South-West, and draws to the eastward of south in the evening.
At times the land wind veers round the compass, and is then generally stronger than usual; blowing fresh for a short time from North-East, and bringing a parching heat from the land; upon these occasions the seabreeze comes in from a more western point, and is lighter.
At Swan River, in the months of December, January, and February, the seabreezes are very strong, for intervals of from three to five days; during which time they blow fresh throughout the night--drawing to the southward after midnight, and towards sunrise to South-South-East and South-East, but more moderate. In the middle of the day, they back again to the southward, and soon to South-South-West, from which quarter they blow very fresh until midnight.
Intervals of such weather are from three to five days' duration, and are followed by the like number of days of moderate weather, with winds mostly off the land; sometimes strong gusts from the east, for a few hours, with oppressively hot weather.
I have noticed, that when the seabreeze sets in from a point to the westward of South-West, it does not blow so strong, and generally lulls at sunset; but if more southerly, or from South-South-West, it is a fiery breeze, and often lasts until midnight.
During the prevalence of these strong seabreezes, communication between Gage Road and the shore is very inconvenient--particularly for laden boats.
In March, the seabreezes are not nearly so strong, but are generally moderate, and not unfrequently bring in thick misty weather from southwards, with drizzling rain.
Generally speaking, when the seabreezes are the strongest, the land winds are light, and vice versa.
I cannot speak from experience of the winds or weather during the month of April, at Swan River, but have been told that the seabreezes are moderate, and the land winds of longer duration; calms are frequent--and the weather altogether seems to indicate the breaking up of the summer season; light winds are occasionally felt from the northward, with a dull, gloomy appearance between that point and South-West.
May is the month in which the winter weather fairly sets in, and it rarely happens that the middle of this month passes without the rains having commenced. This season seems to vary but little as to the time and manner of setting in--it is ushered in by blowing weather, from about North-North-East, the wind gradually veering round to the westward, as it increases in strength. The first of this weather usually lasts from a week to fourteen days; then comes an interval of fine weather, generally of a fortnight's duration, and sometimes a month; after which the rains set in more constant, and the intervals of fine weather are shorter; this weather lasts until October, and at times throughout that month.
During the intervals of fine weather the climate is delightful, and the country has a fresh and pleasing appearance; land and seabreezes are as regular as in summer, with the exception, that the latter are much more moderate.
The North-West gales that occasionally occur during the winter months, on the southern parts of the west coast of Australia, are probably felt as far north as Shark's Bay. They blow with great violence, and are accompanied by dark, gloomy weather, and rain. It is then unsafe to be near the land--as the gale that commences at North-North-East, invariably veers to the westward, making a lee shore of the whole line of coast, and between West-North-West and West-South-West blows the hardest.
Fortunately these gales give ample warning; the barometer always foretells their approach, and generally begins to fall three or four days before the commencement of the gale--besides which, there are other never-failing indications of a northerly wind, such as, the change of the current, which (owing to the prevailing southerly winds) usually sets to the northward, but runs strong to the southward during northerly winds--frequently preceding them, and giving more timely notice than the barometer.
A rising of the water is likewise a certain prognostic of a northerly wind; and has been invariably noticed, at Swan River, to precede all gales from that quarter--this, of course, can only be observed while at anchor on the coast.
Another, and perhaps equally certain sign of approaching bad weather, during the winter season (and which is almost certain to be from the northward) is the strength of the North-East winds--as it has been observed, that when the land winds blow strong, particularly from the North-East and the seabreezes are light, with a falling barometer, a gale from the northward will follow. Perhaps these latter remarks, are only applicable to that distance from the shore, where a ship will be within the influence of the land and seabreezes; but as I conceive the limit of that distance to be full 30 miles off shore, a notice of such a symptom of approaching bad weather, may not be altogether useless. I am of opinion, that land winds are at times felt as far off shore as the edge of soundings, which is not less than 30 miles, and generally between that and 40.
(In latitude 30 degrees 25 minutes South and 65 miles from the land, soundings were got from the Beagle, with 185 fathoms of line, upon a coral bottom. Between Swan River and Houtman's Abrolhos, soundings may be had at a greater distance from the land, than off any other part of the west coast.)
The North-West gales are of longer duration, in the latitude of Swan River, and south of that, than they are to the northward; they do not appear to be entirely confined to the winter months, as I am told that a very heavy one was experienced at Swan River, early in March, 1832, and on the 13th December, 1839, the Beagle experienced a strong breeze from the northward, while at anchor in Gage Road, in consequence of which, it was considered necessary to let go an extra anchor.
As it may be satisfactory to know more particularly the progress of these gales, and the effect they have upon the barometer and sympiesometer, I give the details of two that were experienced in H.M.S. Beagle, one at Swan River, in the beginning of June 1838, the other at Houtman's Abrolhos, in the beginning of May 1840; they may be taken as fair criterions of the strength and duration of these gales, the latter having been experienced, probably, within 5 degrees of their northern limit, and the former near the southern extreme of the west coast.
As our barometer had been broken in March 1838, the register of a sympiesometer will be given in describing the gale of June in that year; but as this instrument had been found (by comparison with the barometer) to act exceedingly well, it will be sufficient for our purpose; the GENERAL use of a marine barometer being merely that of a weather glass, for which purpose a sympiesometer is equally good, and more sensitive.
For the gale of 1840, the register of a barometer is shown, which, although 0.2 too low, will serve to show the effect upon the mercury.
At Swan River, on the 24th of May, 1838, the wind was strong and squally from North-East by North; sympiesometer standing at 30.74. During the day the oil commenced to fall, and continued falling slowly until the 30th, when it was 30.16; during the greater part of this interval, the winds were light, generally from some eastern point in the morning, and going round the compass, by north and west, during the day; the nights were mostly calm, a heavy bank of clouds was collecting between North-North-East and South-West and the whole western horizon had a gloomy appearance. On the evening of the 30th, the water had risen considerably at the anchorage, and the stream ran to the southward; a fresh breeze also set in from North-East and gradually veered to the northward, as it increased in strength. On the 31st it blew hard all day, between North-North-East and North-North-West, with dark squally weather, much lightning in South-West and heavy rain, that continued all night. On June the 1st, the gale was at its height, and at 8 A.M. (the sympiesometer having fallen to 29.93) was blowing a hard gale, with heavy squalls and rain, from North-West; towards noon the wind veered to west, but still blew very hard; the sympiesometer now began to rise, and in the evening the wind was West-South-West and had moderated considerably, the weather was also clearer, although heavy clouds still hung on the western horizon.
The next morning (the 2nd) the sympiesometer had risen to 30.26; but this was much too sudden a rise (0.33 in 24 hours) to allow us to suppose, that the favourable change in the weather was to be of long continuance; during the day the oil began to fall again, and the wind veered to West and North-West and on the 3rd blew harder than ever, with heavy rain, thunder, and lightning; and, with the exception of occasional intervals, when the wind moderated, this weather continued until the 10th. The wind during this time was variable, between North-North-West and West-South-West, the sympiesometer between 29.81 and 30.16--falling with the North-West winds, and rising as the wind veered to west and West-South-West.
This gale, which may be said to have been of ten days' continuance, caused a very heavy sea upon the coast; the oldest residents at Swan River said they had never experienced so heavy a sea before. On the 10th the glass commenced to rise steadily, and the weather was fine, with light variable winds, until the Beagle sailed (on the 20th).
Owing to the security of Owen's anchorage, and the good quality of the bottom, the Beagle rode out this bad weather, without causing the slightest apprehension to anyone on board; but had a merchant vessel been in Gage Road, in all probability, she would have added one more to the list of wrecks, that have already done too much in prejudicing strangers against the Swan River settlement.
The gale of May, 1840, at Houtman's Abrolhos, commenced in a similar manner with that already described, but being in a lower latitude, was of shorter duration, and the indications did not precede it such a length of time; still they were in every respect similar.
This gale commenced on the 2nd of May, in the evening, and lasted until the evening of the 4th. on April the 29th, the barometer stood at 30.17 (having been some days steadily high); it then commenced to fall, and on the evening of May the 2nd, was 29.86; during this interval we daily experienced strong East-North-East and North-East winds; they generally commenced after midnight, and lasted until noon; a bank of clouds was also collecting in the North-West and there was occasional lightning in that quarter; the early part of May the 2nd was nearly calm, and there was a heavy bank of clouds between North and South-West. After noon a light breeze sprang up from North-West which gradually freshened; and during the night the barometer fell 17-hundredths.
At sunrise on May the 3rd, there was a fresh breeze from North-North-West and the weather had a very dull and gloomy appearance, the wind increasing rapidly, and by noon it blew a heavy gale at West-North-West; the barometer had fallen to 29.58, at which it continued until midnight, when the wind drew to the southward of west, and the mercury began to rise. The gale continued unabated, with squalls and rain, until noon of the 4th, although the barometer had been rising since the previous midnight; in the afternoon the wind moderated, and the weather became fine.
From this it would appear that the barometer gives ample warning of an approaching North-West gale, as it had been falling nearly four days before the commencement of the bad weather, this alone ought to be sufficient to put a man upon his guard if near the shore. Between April the 29th (the first day of the fresh north-easterly winds) and May the 3rd (when the gale was at its height, and the wind began to draw to the southward of west) the mercury had fallen 6-tenths. The change of current did not precede the wind, but changed with it; when the gale was strong from North-West and West-North-West the current ran a knot an hour to the South-East, and when the wind changed to South-West it ran with the same velocity to the North-East.
The west coast of New Holland is at times visited by sudden squalls, resembling hurricanes. I was told by the master of an American whaler, that in March 1839, when in company with several whalers off Sharks' Bay, he experienced some very bad weather, which came on suddenly, without having given any previous warning, but it was not of long continuance; the gusts of wind were very violent, shifting suddenly to all points of the compass. Some of the ships suffered considerable damage, in loss of topmasts, etc. others in sails, but all more or less. I think the first squall was from North-East off the land.
The American whalers that resort to the west coast of Australia, are upon different parts of it at all seasons of the year; their range is between the parallel of 10 and 50 degrees of south latitude. In the summer they fish to the southward, and at that season visit Swan River and King George's Sound, for refreshments; but during the winter months they are rarely to the southward of Sharks' Bay; numbers are to be met off the North-West Cape.
Between the parallels of 40 and 45 degrees they meet much bad weather, as it is generally blowing strong with a heavy sea; but between 45 and 50 degrees the weather is much more settled, and finer. November is said to be generally the finest of the summer months, the winds are mostly moderate, and the weather more settled than at other periods.
Two gales that were experienced by the Beagle in November 1837, between the islands of St. Paul and Amsterdam and Swan River, will serve to show the different effects upon the barometer by gales from opposite quarters, one being from North-West and the other from South-East.
On November the 1st, the barometer stood at 29.90, having been gradually rising for some days previous to that, and the wind had been fresh between north and west. After 8 P.M. on the 1st, the mercury began to fall, and on the 2nd, the wind was strong from North-North-West--barometer falling all day. During the night it blew a heavy gale, and the barometer fell to 29.34. On the morning of the 3rd the wind veered to the westward, and the mercury began to rise, the weather also became more moderate, and gradually fine.
On the 8th of the same month, the barometer was 30.05 at 8 P.M. with fine weather, wind South-East by East, it then commenced to fall, and at 8 P.M. on the 9th was 29.80, and blowing a heavy gale at South-East, which continued all night, and until 8 P.M. on the 10th, at which time it became more moderate, and the barometer began to rise.
What a different effect these gales had on the barometer; that from the North-West causing the mercury to fall nearly 6-tenths, whereas, the last, from South-East only lowered it 2-tenths, and 5-hundredths; they were of equal strength and duration, and both accompanied by heavy rain.