156 PHYSICAL GEOGRAPHY OF THE SEA, AND ITS METEOROLOGY. 



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

 hemisphere the debatable ground appears by the table to extend 

 pretty nearly from 25° to 50^ N. By the plate the two wmds fii'st 

 become equal between 25° and 30° ; the two curves then recede 

 and approach very closely again, but without crossing, between 

 35° and 40°. In the southern hemisphere, the conflict between 

 the polar and equatorial indraught, as expressed by winds vdth. 

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

 tv,^o cmTes 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 atmo- 

 sphere 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 horizoii in the several bands 

 »jid the calm belts., ^^^ ^^ g^ch hemisphere. Supposing a like distri- 

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

 cahn belts of the tropics across the continents (Plate YIII.), and 

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

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

 are nevertheless considered as " clri/ countries," by reason of the 

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

 belt of Cancer, w^hich at sea lies between the parallels of 28° and 

 37° (Plate YIII.), but which, according to Su' John Herschel,* 

 reaches higher latitudes on shore, it will be perceived that the 

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

 ing in rivers, which countries are therefore abmidantly supplied 

 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 v/inds. These 

 '** dry " winds traverse a comitry abomiding 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 moistm-e, except as dew, until they reach 

 the sea, and are replenished with vapom^ thence in sufficient quan- 

 tities to make rain of; whereas the winds which come out on the 

 polar side leave moistiu-e enough as they come for such rivers as 

 the Obi, the Yenisei, the Lena, and the Amoor, in Asia ; the Mis- 

 Rom'i, the Sascatchawan, the Eed Eiver of the North, and others, 

 * § 273, p. G14, vol. xvii. (Phys. Geog.), Encyclopedia Britannica. 



