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, and 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. In 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 mentioned by Humboldt is upon the autho 

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

 the single month of February. A parliamentary report on the sickness among the troops 

 at Sierra Leone in 1828, states that during the three months of June, July, and August, 

 there fell 313 inches ; and for the whole year, the amount was estimated at 400 inches. But 

 the greatest fall on record is that observed by Mr Yule at Churra, north-east of Calcutta, 

 among the Khasian Mountains. In the single month of August there fell 264 inches, of 

 which 150 inches fell in the space of five consecutive days. Another observer at the 

 same station measured 500 inches in the space of seven months. 



2. Both within the tropics, and near their limits, there are extensive tracts of the globe 

 in which rain is either entirely unknown, or it occurs so rarely, and in such small quanti 

 ties, that a copious shower is quite a phenomenon. These districts consist for the most 

 part of rocky or sandy deserts, where the highly-heated atmosphere does not contain 

 sufficient moisture to admit of precipitation, under any decrease of temperature. In the 

 New "World, the rainless regions comprise portions of California and Guatimala, the 

 Mexican table-land, and the coast-line of Peru. Those of the Old World comprehend an 

 immense territory, stretching from Western Africa through the Sahara, a part of Egypt, 

 Arabia, and Persia, into Beloochistan, with another great zone, north of the Himalayas, 

 including the table-land of Thibet, the desert of Gobi, and a portion of Mongolia. 



3. In both continents, likewise, districts within and near the zone of the 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 



