in October, with a strong current from the N. E. towards the S. W. At this period we must remember that the sun is fast approaching towards the equinoctial, which he crosses nearly about the 22d of September. As his declination afterwards increases from seven to fifteen degrees S. which is between the 10th and 31st of October, his absence from the northern hemisphere begins to be felt; and as he at the same time rarefies the air both by sea and land to the southward of the equator, the warm air then over the Indian Ocean, but particularly over the eastern side of the continent of Africa, as usual ascends, and the cold air from the N. meeting the perennial east wind, they pass forward progressively, beginning where the rarefaction takes place, and probably continuing to an immense distance, and thus form the N.E. monsoon. The exact point where the northerly wind terminates I shall not, in this place, at. tempt to ascertain; but we may venture to suppose, that it must be at least as far towards the N.E. as the west side of the Thibet and Napal mountains, separating India from China, and which in winter are always covered with snow. From this frozen eminence a current of cold air will move with considerable velocity towards the tropic, on the approach of the sun, until the equilibrium is restored; but at the latter end of January, the sun again beginning to return towards the N. produces a sensible effect on the air; for in proportion as he approaches towards the equator, the current of air in the gulf of Bengal, near the land, takes a different direction. About this time the wind, immediately on the coast of Coromandel, no longer blows violently or regularly from the N.E. as in the commencement of the monsoon, but first abates in strength (like a current of water when the level is nearly restored) and then changes daily to regular land and sea breezes, which of course, near the coast, are obviously occasioned by the alternate rarefaction of the air by sea and land.

In the Mosambique Channel the monsoons correspond nearly with those on the Malabar coast, if not in their commencement at least in their duration. The S. W. monsoon begins in April and continues till November. The N.E. then succeeds, and continues until April; but the S. W. monsoon in this channel is the fair sea. son, and the wind varies sometimes towards the S. E. and E.S. E. on either coast, about the middle of November, where also there

are generally, regular land and sea breezes. The N.E. mon. soon regularly begins early in November near the Comero islands, and the north end of Madagascar, but seldom extends be. yond St. Augustine's Bay to the southward, which is near the southern tropic. But on the east side of Madagascar, beyond the islands of Bourbon and Mauritius, towards what are called the Eastern Islands, the S. E. perennial prevails all over the Indian Ocean, from the latitude of 11 to 28 degrees S. whilst to the S. and eastward of the islands of Java and Sumatra, the N.W. and S.E. monsoons alternately prevail at the different seasons of the year. The S.E. monsoon in these seas, according to Monsieur D'Apres, commences in the month of April and continues till November, when it changes to the N. W.; but between the two monsoons the winds and currents there, as in other places, are light and variable. Throughout the whole extent of the Eastern Isles, as far as Timor and Solor, the N.W. monsoon brings bad weather; this wind is violent and accompanied with rain. The stormy weather continues all January and until the middle of February, it then abates, and entirely ceases about the end of March. In the month of April the variable winds render the weather mild, and the sea is affected only by occasional squalls of short duration. In May the S. E. wind becomes settled, and blows incessantly in June and July with considerable strength: during this time, however, the weather is fine, with a clear serene sky until the end of September. In the month of October the S. E. monsoon dies away, and the winds be. come variable till they again settle in the N.W. As Dr. Halley mentions the difference of the monsoon in this part of the Indian Ocean S. of the equator, but does not attempt to account for it, I shall in this place take upon me to offer some conjectures on the subject.

The earth, during the summer, as it has often been before ob served, receives and retains a greater degree of heat from the sun than the sea, which, by its constant motion and change of surface, is at this season infinitely cooler than the land, particularly in the torrid zones; but during the winter, in the temperate zones, the sea is much warmer than the land, particularly in high latitudes. In the summer, therefore, the great body of air, near very extensive continents, will of course move from the sea to the land, and

in the winter quite the contrary will happen. Now if we refer to the map, we shall find New Holland an immense tract of land to the S. E. of the Sunda and Molucca islands; and, if unbroken by a mediterranean sea, almost equal in extent to all the land in Europe. It is situated partly within and partly beyond the tropic. When therefore the sun is nearest his highest declination N. which of course is the winter of the southern hemisphere, and rarefies the air over the continent of Asia, the current of air in the southern hemi. sphere, independently even of the regular perennial wind, will move from the S.E. to restore the equilibrium to the N.W.: on the contrary, in the month of November, December, and January, whilst the sun is nearly vertical over a part of New Holland, the current of air through the Sunda and Molucca islands will come from the N.W. to fill up the vaccum made by the rarefaction, and thus occasion an alternate monsoon of S.E. and N.W.

This obvious manner of accounting for the N.W. and S.E. mon. soons on the east side of the Indian Ocean, would not have escaped the discernment of the learned Dr. Halley, had he not become weary of the subject, or directed his attention towards pursuits of still greater importance. He closes his remarks concerning this subject with observing, "On this same principle to the southward of the equator in part of the Indian Ocean, the N.W. winds succeed the S.E. when the sun draws near the tropic of Capricorn. But I must confess that in this latter occurs a difficulty not easily to be accounted for, which is, why this change of the monsoons should be any more in this ocean than in the same latitudes in the Ethiopie Ocean, where there is nothing more certain than a S.E. wind all the year."

Having said every thing that appears to me necessary respecting the monsoons in the gulf of Bengal, the gulf of Sind, and the Indian Ocean, I shall offer a few words on the winds in the China seas, and afterwards direct the reader's attention to the winds in the Arabian and Persian Gulfs.

In the gulf of Siam, on the coasts of Campogia or Campoge, of Cochin China, and in the gulf of Tonquin and China (according to Monsieur D'Apres de Mainvillette) the S.W. monsoon commences on the coast in the course of the month of April; but if out at sea in those parts, it does not change until a month later. It is for this

reason, that on the north part of Borneo to the islands of Paragoa and Luconia, it is seldom known to blow constantly but from the 1st to the 15th or 20th of May. As the S.W. monsoon continues only about six months, and commences near the coast, it there ceases first likewise in the same manner, and is immediately suc. ceeded by the N.E. Thus, it is evident, the N.E. and S.W. mon. soons reign constantly to the north of the line to the eastward, as well as in the gulfs of Bengal and Sind; whilst the N. W. and S.E. monsoons to the eastward, are absolutely confined to the south of the line, within the reach of the influence of New Holland. It has been already observed that the word monsoon, is derived from the Persian word mousum, season. The violent hurricanes in those seas are, by our sailors, called tuffoon or typhon; this term is derived either from the Greek Tupwv, or from the Persian word toofan, a whirlwind or tempest. Whether the Greeks or Egyp tians gave this word to the Persians, or received it from them, it is not necessary in this place to determine; but these and many other professional terms used by mariners in all parts of the east, both by the natives and Europeans, respecting the winds and weather, together with many of the ports of great resort on the different coasts in the Indian seas being called by a particular country name, with the addition of bender, signifying a port, and banksala, a magazine, render it extremely probable, and we may say almost certain, that the Persians were the earliest navigators of the In. dian, and perhaps the China seas. The Portuguese succeeded them, and adopted the sea terms of their predecessors, which are now used by all other maritime nations, being however very much disguised by different European orthography and pronunciation.

In the Arabian and Persian gulfs, according to Mons. D'Apres, the winds are very different, although he remarks they are separated only by Arabia. They blow," says this author," in the Red Sea almost nine months in the year from the southward, that is from the end of August to the 15th of May, and sometimes to the end of that month, when the wind changes to the N. and N.N.W. and ge. nerally continues in that quarter to the end of August, but sometimes the land and sea breezes prevail."

In the gulf of Persia the N.W. wind blows from the month of October to July, and about three months from the opposite quarter. These winds, however, are not so regular as those in the Red Sea.

being often interrupted by fresh gales from the S.W. principally from Cape Moçandon, and sometimes by land breezes.

2. Etesian Wind.

[ld.

THROUGHOUT the whole Mediterranean, but mostly in the eastern branch, including the Adriatic and the Archipelago, the N. W. winds prevail in the summer months. During the winter they are variable, but the S. E. and S. W. blow frequently with great force near the two solstices.

In Greece, particularly in the Morea, which is almost sur. rounded by the sea, the Etesian winds, according to Aristotle, and other Grecian writers, blow about forty days, with their prodromi which precede them, as their name itself implies, about eight or ten days, making about fifty, both these together correspond nearly in their commencement and duration with the Khumseen wind in the Arabian Gulph. But the summer Etesia in Greece and the Morea come from the N. W. and the Khumseen from the S. W. These winds are likewise noticed by Pliny and Seneca, and also by Cicero, (Nat. Deor. ii. 53.) who says that in Italy they are equally comfortable and salutary to men, beasts, and birds, and likewise beneficial to vegetation, by moderating the violent heat of the weather during the inclement season of the dogdays.

When the sun advancing towards the N. has begun to rarify the atmosphere of the southern countries of Europe, the spring Etesia commence in the Mediterranean, which according to the ancients, blow in Italy during the months of March and April, and were called by the Roman writers the Favonii. Their influence at first will be but slightly felt, but as soon as the earth becomes considerably warmer than the Mediterranean, the current of air will then move from the sea towards the land, and consequently produce the Favonii or gentle western breezes, to which those authors allude.

For some weeks after the equinox, the warmth of the sun will not be very sensibly felt on the frozeu Alps; but as his declination increases, some time even before the summer solstice, a part of the ice and snow on those mountains will begin to dissolve, and, according to the observation of Lord Bacon, put the air in motion from the northward, to fill up the vacuum produced by the rare. faction of the air over the southern part of Italy. This wind,