374 THE PHYSICAL GEOGRAPHY OF THE SEA. 



tralia on the other, tend to draw the wind in toward the land, 

 and so retard the edges of the southeast trades, thus giving the 

 calm belt the curved form shown in the plate. 



702. In the winter time, and during the northeast monsoon, 

 The winter mon- there is iu the calm belt which intervenes between 

 ^^''°^- that monsoon and the southeast trades a belt of 

 winter or westerly monsoons. It, too, is curved, as shown (Plate 

 YIII.) by the two lines drawn to represent its mean limits about 

 the 1st of March. This is a most remarkable phenomenon, for 

 which no satisfactory explanation has been suggested. It ex- 

 tends nearly, if not entirely, across the Pacific Ocean also, and the 

 winds all the way prevail from the westward. The extreme 

 breadth of this winter monsoon belt is about 9° or 10° of latitude. 

 In the Indian Ocean, its middle is between the equator and 5° 

 S. ; in the Pacific, between the equator and 5° N. ; in the Atlan- 

 tic, between 5° and 10° K. In the Atlantic it is a summer mon- 

 soon easily to be accounted for. This belt of sub-monsoons, 

 considering its great length and small breadth, is one of the most 

 remarkable phenomena in marine meteorology. 



703. The northwest monsoons of Australia come from this belt; 

 The monsoons of thcrc It is widcucd, for these winds extend far down 

 Australasia. ^^^ west coast of that coutincnt. The Malayan and 

 Australasian archipelago have a complication of monsoons and 

 sub-monsoons. The land and sea breezes impart to them peculiar 

 features in many places, especially about the changing of the mon- 

 soons, as described by Jansen in his appendix to the Dutch edition 

 of this work : " We have seen," says he, " that the calms which pre- 

 cede the sea-breeze generally continue longer, and are accompanied 

 with an upward motion of the air ; that, on the contrary, those 

 which precede the land-breeze are, in the Java Sea, generally of 

 shorter duration, accompanied by a heavy atmosphere, and that 

 there is also an evident difference between the conversion of the 

 land-breeze into the sea-breeze, and of the latter into the former. 

 Even as the calms vary, so there appears to be a marked differ- 

 ence between the changing of the monsoons in the spring and in 

 the autumn in the Java Sea. As soon as the sun has crossed the 

 equator, and its vertical rays begin to play more and more per- 

 pendicularly upon the northern hemisphere, the inland plains of 

 Asia, North Africa, and of North America are so heated as to 



