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A represents the entry, C the stair-case seen from above, D, holes like pigeon-holes in the wall. This, and the foregoing fketches, are drawn from memory; and the elevation is too high in proportion to its other dimensions.
IN continuation of our account of the tropical winds, we fhall briefly enumerate the principal inflections of the monsoons, and the other tropical winds of lefs extensive influence, that have been taken notice of, within or near the tropics, with the causes of these inflections.
Particular inflections of the monsoons.
In all that part of the Indian ocean, that lies between the island of Madagascar and Cape Commorin, the wind blows constantly from W. S. W. between the months of April and October; and in the opposite direction from the month of October till April, although with some variation in different places; these winds being neither so strong nor so constant in the bay of Bengal, as in the Indian ocean. It is likewise remarkable, that the S. W. winds, in those seas, are more southerly on the African side, and more westerly on the Indian, as appears distinctly in but these variations are not repugnant to map; the general theory. It is sufficiently known, that in every part of the globe, high lands are much colder than low and flat countries; and as that part of Africa which lies within the tropics is very high VOL. vii.
and mountainous, the cold in these regions is much greater than in the more flat countries of Arabia and India; so that the wind naturally blows from these cold regions, in the summer season, towards the warmer continent of Asia ; which occasions those infleations of the wind to the eastward, that take place in these seas during the summer months. This effect is still farther promoted by the peninsula of India, the kingdom of Siam, and the islands of Sumatra and Java, on the eastern part of this ocean, lying so much farther to the south than the kingdoms of Arabia and Persia, which naturally draw the wind towards them, and produce the easterly variation of the monsoon which takes place in this part of the ocean, while the sandy deserts of Arabia draw the winds more directly northward, near the African
In the eastern parts of the Indian ocean, beyond the island of Sumatra, along the southern parts of China, and among the Philippine islands, &c. to the north of the equator, the monsoons observe a different direction, blowing nearly due south and north.
Here the greatest part of the warm continent lies to the west of this district, which makes the wind naturally assume this direction. A little farther to the eastward, among the Marianne islands, the general trade-wind takes place, there being no continent to the north of them to occasion monsoons.
The monsoons are as regular in the eastern part of the Indian ocean for a small space, to the south of the equator, as they are to the north of it; here a northern monsoon sets in from the month of October till April, and a southern from April till October; and
here, as well as to the north of the line, we find the direction of the monsoons varying in different places, according to particular circumstances. About the island of Sumatra, and towards the west of Java, the monsoons set in nearly from the north and south; but towards Celebes and Timur, they begin to tend a little more to the east and west, gradually declining as they approach the coast of New Guinea, near to which the northerly monsoon, from October till April, blows from N. W. and the opposite monsoon from S. E. between October and April. The reader will easily perceive that these monsoons are occasion. ed by the continent of New Holland; which being heated by the sun when in the southern signs, draws the wind towards it in the summer season, in the same manner as the continent of Asia produces the monsoons to the north of the line. The easterly deflection of this monsoon is plainly occasioned by the near approach of the large island of New Guinea, to the northern point of New Holland.
In the Red Sea the monsoon fhifts as regularly as in other places; but being influenced by the coasts,, it tends a little more to the north and south than in the Indian ocean.
Irregularities in the monsoons on the eastern coast of Africa.
On the coast of Africa, to the south of Cape Corientes, and about the southern parts of the island of Madagascar, the regular trade-wind from the S. E.. takes place between October and April; but from April till October, the wind blows from W. or N... W. and is at that season exceedingly cold..
This is evidently occasioned by a cause already taken notice of; for notwithstanding the high and cold nature of this part of the continent of Africa, yet when the sun is to the south of the line, his powerful influence at that season so far abates their natural degree of cold, as not to interrupt the general trade-wind between the months of October and April. But when he returns to the northern hemis→ phere, the high mountains of Africa resume their native coldness, and a strong current of air, rushing from them to warmer regions, repels the general trade-winds by its cold and more powerful blast, so as to produce the intemperate monsoon which here takes place between the months of April and October.
From Mozambique to Cape Guardafui, the monsoons are a little more irregular than in the other parts of the Indian ocean. It is observed that here, between. October and January, the winds, though chiefly from the north, are variable. In January the N. E. mon'soon sets in, and continues regular till the month of May. From May till October the winds, though. chiefly from the southern points, again become variable, but in the months of June, July, and August, there are frequent calms, especially about the bay of Melinda, which sometimes continue for several weeks. together, and extend only about one hundred leagues. from the fhore.
Before we can explain clearly the cause of this irregularity, it will be necefsary to attend to the direction of the wind, on each side of this track, at each particular season. In the months of October, November, and December, the winds are here variable,
but chiefly from the north. Now during these three months, to the south of this, beyond Cape Corientes, the wind blows from the S. W.; at the Red Sea, and all to the north of this track, the wind, during this season of the year, is from the N. E.; and as the sun is then perpendicular to the bay of Melinda, these opposite winds, here meeting and opposing one another, and being both of them stopped in their course westward, by the cold regions of Africa, will naturally produce the variable winds. here observed, according as the one or the other of these three balancing powers happens to predominate: Although, as the coast here runs away towards the S. W. it is natural to expect that the northerly wind which follows the same direction, should more frequently prevail than those that are opposed to it, especially when we consider that the island of Madagascar, now beginning to be warmed by the influence of the sun, will concur in drawing the wind to the southward; and when the continent of Africa is more heated in the months of January and February, it does not oppose the easterly monsoon, so that the winds become then more fixed than before. But in the months of June, July,. and August, the wind to the south of Cape Corientes is from the N. W.; and near the Red Sea, and throughout the northern part of the Indian ocean, the S. W. monsoon is then in its greatest vigour; so that on each end of this district the wind is blowing in an opposite direction; from which result these calms. about Melinda, which we have just mentioned..
To be continued..