Page:Popular Science Monthly Volume 7.djvu/501

Rh sun from the broad expanse of the Indian Ocean, we find that in the eastern Himalayas the rainfall varies from 200 to 600 inches a year, and that at Mahabaleshwar, where the clouds drift against tlie high ridge that lines the west side of the peninsula, it is 248 inches, but that at Courtallum it is only 40 inches, at Bangalore 35 inches, at Cape Comorin 30 inches, and at Bellary in Mysore 22 inches, which is as low as in any part of England,

—Outside the zone of periodic winds and rains comes a double belt, one girdling the world in the northern, and the other in the southern hemisphere, the breadth and area of which are greatly modified by local circumstances, within which no rain ever falls. These belts are estimated to include altogether an area of 5,000,000 square miles, but it is impossible to make any calculation that is at all precise, because round the tracts that are entirely rainless are regions in which rain falls but rarely, which again pass gradually into the two rainy zones, through countries like Southern Palestine and the Gangetic plain, which, though usually rainy, are liable at intervals to years of drought. These belts of rainless land near the tropics contain some of the most hopelessly dreary country which the world can show. Beginning with the west of the old continent, we have along the tropic of Cancer in Africa the Sahara or great desert, on the southern border of which the rains cease at 16° north latitude, and begin again on the north at 28°. Passing farther east, the southern rains cease in the countries on the banks of the Nile between 18° and 19°, and the northern begin between 27° and 28°. Passing into Asia, there is a great rainless tract in Arabia of which we do not know the exact bounds, and it reaches through Beloochistan over into the delta of the Indus, where it does not cover more than 4° of latitude. From this point the rainless zone turns to the northeast and extends to 30° north latitude. Crossing the great Himalayan chain it includes the high table-land of Thibet, but does not appear to reach into the Chinese Empire. In South Africa there is a sandy, desert, rainless tract on the north of the Orange River, between 24° and 28° south latitude, and a great part of the interior of Australia seems to be nearly or quite rainless. In North America the rainless belt includes the Californian peninsula, and extends round the northern end of the Sierra Madre chain past Chihuahua and Monterey to the shores of the Gulf of Mexico between latitudes 24° and 26°. In South America it includes between latitudes 23° and 27° the northern province of Chili, and, through an extensive low tract in the interior of the continent belonging to the territory of the Argentine Confederation, rain is very unfrequent and small in quantity.

—From about latitude 80° on each side of the equator to the poles extends a region of everchanging and variable winds, and of rain that is irregularly distributed throughout the whole year. Sometimes in these middle