JlTNR I, 1883.] 



THE TROPICAL AGRICULTURIST. 



977 



UNEQUAL DISTRIBUTION OP RAINFALL. 

 Our Australiau frieniU who specially know what it 

 is to sufl'er from drought, scarcity of pasturage, floclis 

 and herds aud destructive bush lires, will now learn 

 from their fellow-colonists who have hai' such a strik- 

 ing and, we hope, refreshing experience in ("nylon, 

 that it is ijuite possible to have too much even of 

 such a good thing as rain. If we could ouly get mixed 

 up with Australia and strike an average of moisture, 

 we should no doubt feel that the arrangement would 

 1)6 an improvement on the existing state of things. 

 We are reminded of the old doctor who said: — "No 

 doubt when you knock your shin against a sharp 

 object and are wincing from the pain, jou think you 

 could improve the human frame by placing the calves 

 of the legs in front of the bones instead of behind." 

 The true philosophy, however, without doubt, is that 

 there are good and beneficent reasons for arrangements 

 a'ld phenomena which we cannot comprehend or only 

 partially understand, especially in the case of the 

 grand cosmic causes which inlluence rainfall. Even in 

 Scinde, where rain sometimes does not fall tor years, 

 aud where the average is ouly four inches, irrigation 

 has converted portions into verdant gardens, and the 

 s;ime agency has been so successful in Australia, that 

 explorers have ceased to regard as hopeless the central 

 deserts of sand and stone and spinifex, now scenes 

 of horrid and forbidding desolation, into which brave 

 men have ventured ouly to die in the wild delirium 

 of thirst. It seems more difHoult to apply a remedy 

 ii- such cases as that of Clierapunjee at the base of 

 the Himalayas, tli'' average annual rainfall of which 

 is doss on 000 inches (50 fo'it !), and where one year 

 considerably over 800 inches fell, no less than 3.S0 

 inches comining in the one month of July! Forty-eight 

 inches or fom- feet of rain have been known to fall 

 here in a few hours of one day. That is the climate 

 truly to take the starch out of the stiff and to convert 

 men of delicicnt backbone into linj;raess. Here, in Cey- 

 lon, our average range is from 80 inches at Maunar 

 to 250 (280 were recorded one year) at Padupolla, uuder 

 " the shadow of the Peak." Apart from the agencies 

 which produce raui currents, there can he no doubt that 

 the deposition of moisture is chietly influenced liy mount- 

 ain ranges. J^s we go southwards from Colombo and 

 nearer tlie hills, the rainfall becomes greater ; the reverse 

 process being observed as we go northwards and away 

 from the influence of the mountains. Wami euiTents of 

 ail- striking on the bases of mountains part with more 

 and more of their moistm-e as they are forced upwards 

 into the cold. But a point is reached where rainfall 

 commences to decrease, and, at last, iu the case of such 

 high mountains as the Himalayas, it ceases altogether, 

 aud whUe tlie Khassia HiUs at 4,000 feet elevation on 

 the base of the Himalayas are deluged and send floods 

 down into the valleys of Sylhet, the dwellers in the 

 regions on the opposite side of the vast ramjiart sigh 

 iu vain for even a portion of the cloud treasures. No 

 doubt experiences were different before the " gi-and aljode nf 

 snow " was upheaved, and they will probalily a^'ain chan^'e 

 when Mount E\erest, Kinchiujinga and Maha Devi 

 cease to reign over " the upper crust of the globe. " 

 Meantime, all accumulated experience does but strengthen 

 our conviction that the presence of forest depends 

 on the presence of rainfall, ami that the largo num- 

 ber even of scientific men who believe they can by tree- 

 planting convert arid regions into plurial, are mistaken 

 123 



In Roinde, for instance, we do not believe that any 

 .imonnt of "forestation" would sensibly increase the 

 average rainfall of four inches, however much tlie 

 action of irrigation and the presence of trees and plants 

 may modify the climate otherwise. And so with the 

 converse case: we feel confident that the denudation 

 of forest for many miles around Cherapunjee would not 

 lessen the average rainfall, though it would lead to the 

 more rapid passage downwai-ds of the waters and the 

 more serious flooding of Sylhot. Here, in Ceylon, the 

 I'ecorded ligiu'es shew that forest felling has not afl'ected our 

 rainfall a decimal : indeed, after half-a-century of cofFee- 

 planting our complaint is of too much and unseason- 

 able rain ; the very complaint which farmers in England 

 make, after a thousand years of clearing and cropping. 

 We can no more alter the gi'eat influences of nature 

 by our puny operations on the surface of a few districts 

 of the globe, than we can snccoed iu makhig one hair 

 white or black, seize the oceau by its mane, en' chain 

 the winds which iu obedience to a law which is now 

 largely understood, go " circling about continually." We 

 have before us as we write a map which shews rainfall 

 with reference to the prevalence of forest trees in India, 

 published iu the Indian Forester to illustrate an able 

 paper by Dr. Brandis on the distribution of forests in 

 India, and also a somewhat similar map, coloured to 

 shew the meteorology of India, and used by Sir Joseph 

 Fayrer to illustrate a most interesting pamphlet on the 

 Rainfall and Climate of India. Both maps teach the 

 same lesson, that, as far as rainfall is concerned — the 

 deposition of moistm-e — the climate of districts depends 

 on their contiguity to or hositiou in regard to the in- 

 fluence of mountain ranges. The rainiest region in India 

 is on the western face of the Himalayas ; the next raini- 

 est is along "the Western Ghauts" of the Peninsula, 

 from Bombay to Cape Comorin. In the Indian Forester's 

 map. white indicates the arid zone, under 15 inches of 

 rauifaU iucludiug the inland portions of Southern India 

 and all that portion of India north of Delhi aud from 

 Kurrachee to Peshawiu'. Next comes the dry zone, 

 (light gi-een) from 15 to 30 inches, including a good deal 

 of northern India and of the central portion of the 

 Peninsula. The intermediate zone (light blue), 30 to 75 

 inches, includes the larger portion of India and ( 'eylon. 

 The figm-es for rainfall in the case of om- island are 72 

 inches against Colombo and 85 for Kandy. The true 

 figures are :-- 



Colombo 86J inches 



Kandy 82 „ 



but portions of our island, Ambagamuwa for instance, 

 ought to be coloured deep blue as in tho moist zone 

 above 75 inches. The Deodar (cednis deodara) is 

 refered to the arid zone under 15 inches, behind the 

 Himalayas ; sal ( shorea robusta) and babul (acacia arabica) 

 to the dry zone, 15 to 30 iuclies ; caoutchouc (iicus elastioa) 

 and sandal (santalum album) to the intermediate zone, 

 30 to 75 inches : aud teak (tectona gi-andis) to tlie moist 

 zone, above 75 inches. The northern limit of this piiuce 

 of timbers is mai-ked by the course of the Irrawaddy. 

 Mr. Vincent's report on our Ceylon forests is, we believe, 

 to be accompanied by a carefully compUed map shewing 

 rainfall and its influence on tree vegetation. But our 

 chief interest at present centres in the south. west mon- 

 soon which, if it has not ac'ually reached us, has cert- 

 ainly sent foi-ward some its most torcihle a •nnl-cnuriirs 

 in the shape of rainstonns. Sir Joseph Fayrer in his 

 able paper, shews the great influence of the physical 

 peculiarities of a country, in determining the quantity, 

 the distribution and the periods of the rainfall and he 

 traces the origin of rain to the gaseous envelope of 

 nitrogen and oxygen by which oitr globe is surrouii'Ied 

 to a height of forty or fifty miles. Into this atn.osphere 

 rises watery vapour from the ocean, lakes, rivers. A-e., 

 until saturation fakes place or until cold condenses tho 

 vapour into clouds, rain or dew. On the conditions 

 which affect evaporation ami condensation, rauifall de- 



