§ SiA. EASTING OF THE TRADE-WINDS, ETC. 157 



The wind curves (Plate XV. and the table) afford a very striking 

 view of these medial bands, as the parallels in either hemisphere 

 between which the winds with northing and the winds with south- 

 ing are on the yearly average exactly equal. In the northern 

 hemisphere the debatable ground appears by the table to extend 

 pretty nearly from 25° to 50° N". By the plate the two winds first 

 become equal between 25° and 80° ; the two curves then recede 

 and approach very closely again, but without crossing, between 

 S6° and 40*^. In the southern hemisphere, the conflict between 

 the polar and equatorial indraught, as expressed by winds with 

 southing and winds with northing, is more decided. There the 

 two curves march, one up, the other down, and cross between 

 the parallels of 35° and 40° S., thus confirming what from other 

 data we had already learned, viz., that the condition of the atmos- 

 phere is more unstable in the northern than it is in the southern 

 hemisphere. 



354. Such, for the winds at sea, is their distribution between 

 The rainless regions the two halvcs of the horizou iu the several bands 

 and the calm belts. ^^^ ^^ ^^^^ hemisphere. Supposing a like distri- 

 bution to obtain on shore, we shall find it suggestive to trace the 

 calm belts of the tropics across the continents (Plate VIII.), and 

 to examine, in connection with them, the rainless regions of the 

 earth, and those districts of country which, though not rainless, 

 are nevertheless considered as " di-y countries," by reason of the 

 small amount of precipitation upon them. So, tracing the calm 

 belt of Cancer, which at sea lies between the parallels of 28° 

 and 37° (Plate VIII.), but which, according to Sir John Her- 

 scliel,* reaches higher latitudes on shore, it will be perceived that 

 the winds that flow out on the north side blow over countries 

 abounding in rivers, which countries are therefore abundantly su])- 

 plied with rains. Hence we infer (§ 350) that those winds are rain 

 winds. On the other hand, the winds that flow out on the equa- 

 torial side blow either over deserts, rainless regions, or dry coun- 

 tries. Hence we infer that these winds are dry winds. These 

 " dry" winds traverse a country abounding in springs and rivers 

 in India, but it is the monsoons there which bring the water for 

 them. The winds which come out of this calm belt on its equa- 

 torial side give out no moisture, except as dew, until they reach 



* § 273, p. 614, vol. xvii. (Phjs. Geog.), Encyclopedia Britannica. 



