AQUEOUS ATMOSPHERIC PHENOMENA. 471 



your land in his due season, the first rain and the latter rain, that thou mayest gather 

 in thy corn, and thy wine, and thy oil." These two seasonal events were of vast 

 importance to the Jews, though it is a mistake to suppose that rain seldom falls in 

 Palestine except at those eras. It falls copiously then, arid also occasionally through the 

 winter months, its entire cessation being in the interval between May and October. 

 Prominence is given to the two rains referred to, on account of their abundance, and 

 especially the time of their occurrence, the success of the agriculturist depending in a 

 great measure upon those plentiful showers. The periodical tropical rains do not fall for 

 any considerable time without an intermission. After a fine morning, the clouds in 

 general gather towards noon ; the shower descends with great violence for four or five 

 hours ; and towards sunset, the sky clears, and remains cloudless through the night. 



There is a considerable diversity in the amount of rain during the wet seasons in 

 tropical countries, at different places, and in different years. Jn the ten years from 1817 

 to 1826 inclusive, at Bombay, the average annual quantity was 78*1 inches; but in the 

 course of 1822 there fell 113 inches, while in 1824 the supply did not rise above 34 

 inches ; and hence came famine and pestilence. At Bombay, also, the gauge has received 

 as much as 16 inches of the 78 in the course of twenty-four hours; and while, there, the 

 average annual quantity is as stated above, at Tellicherry, 12 north latitude, it is 116 

 inches, and in the delta of the Indus not more than 20 inches. There is great discrepancy 

 between the amount at Calcutta and Benares ; 72 inches at the former place, and only 46 

 at the latter. The greatest fall in those districts appears to take place on the eastern 

 boundaries of the Bay of Bengal, where, in 1825, at Arracan, nearly 60 inches were 

 registered in the month of July, and about 43 in August, from which, by a rough esti- 

 mate, the annual amount is inferred to be not less than 200 inches. A more extraordi- 

 nary quantity appears to fall in certain sites on the western continent, as in the forests of 

 Guiana, where incessant rains of four or five months are no uncommon occurrence. The 

 most remarkable instance of excessive rain is mentioned by Humboldt, upon the autho- 

 rity of Captain Roussin, who states that more than 160 inches have fallen at Cayenne in 

 the single month of February. Erxleben mentions drops of rain at the equator occasion- 

 ally an inch in diameter. 



All countries however situated within and near the tropics are not thus favoured, as 

 many parts of Africa, Arabia, and the coast of Peru are entirely rainless ; and at Cumana, 

 the annual quantity of rain does not amount to more than eight inches. The rainless 

 regions seem to occur in two belts, one on each side of the equator, which would be 

 consecutive but for the interruption of high lands, the nursery of the showers. The north 

 belt commences in the old world on the west side of Africa. It includes the Sahara 

 between 16 and 28 of latitude, but narrows as it proceeds easterly, extending from 19 

 to 27 on the banks of the Nile. In Arabia, it embraces the low coast, and part of the 

 interior country, but its limits are not accurately known. From hence it passes through 

 Beloochistan to the base of the Himalaya mountains, and beyond that range, there is the 

 rainless table-land of Thibet. The southern belt occurs north of the Gareep or Orange 

 river in South Africa, and includes extensive tracts in Australia. On the continent 

 of America, rainless districts are found north and south of the equator, but the narrowness 

 of the tropical parts of the continent, and the range of mountains that traverse it 

 longitudinally, prevent the appearance of a showerless zone, as in the northern part of the 

 eastern world. In both continents likewise the districts which have their periodical 

 rains are subject to an occasional intermission, and become rainless for considerable 

 intervals, the drought inflicting terrible suffering upon man and beast. Mr. Darwin 

 speaks of the South American droughts being somewhat periodical, for upon comparing 

 the dates of several, he found regular intervals of fifteen years between them. The 



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