Of a Country on the Climate. 



209 



singularly contrasts with its geographical position, and is 

 ■undoubtedly very much owing to the superficial features of 

 the country. 



Evaporatwn.—The amount of evaporation from lakes and 

 runnmg streams has not received that attention from men of 

 science to which it is justly entitled, and the consequence is 

 an exaggerated estimate of the amount of evaporation in 

 warm climates, amongst those whose attention has not been 

 specially directed to its consideration. It may not be out of 

 place here to mention briefly the conditions which are favour- 

 able to evaporation, and to show how clearly dependent is 

 this force upon all other atmospheric phenomena, being in 

 itself merely the result of secondary causes, governed by 

 the geographical position of the country, and its confi- 

 guration. 



In the first place, it must be remembered that evaporation 

 IS dependent on three very uncertain conditions of the atmos- 

 phere—namely, the degree of saturation, the temperature, 

 and the force of the winds. The climate of Victoria, during 

 the summer months, is very warm — the thermometer not 

 unfrequently indicating 100'' in the shade— and if the wind 

 is from the north, the dew point oftentimes falls below SS*."" 

 Such a condition of the atmosphere is most favourable to 



inclies ! » In like manner, in India, Colonel Sykes found, by observations made 

 m 1847 and 1848, that in places situated between 17o and 18o K. lat., on a 

 line drawn across the western Ghauts, in the Deccan, the fall of rain varied from 

 21 to 219 inches.^ The average in Bengal is probably below 80 inches, yet 

 Dr. a. Hooker witnessed at Churraponjee, in 1850, a fall of 30 inches in 24 

 hours ; and in the same place, during a residence of six months (from June to 

 ^irovember),^ a fall of 530 inches ! " — Principles of Geology, p. 200. Sir R. I. 

 Murchison, in his address at the anniversary meeting of the Royal Geographical 

 Society, 24th May, 1852, also gives some curious information on this point. 

 He says, ''My friend, Professor Oldham, in writing to me from Churra Poonjee, 

 in the Khassya Hills, north of Calcutta, states that the rainfall is there about 

 600 inches, or 8^ fathoms per annum; 550 inches of which descend in the six 

 rainy months, commencing in May; and that in one day he measured a fall of 

 25-5 inches.'' .... "The annual amount of rain at Alexandria stands in con- 

 trast to that which I have just mentioned as occurring in places in India, the 

 quantity at the former being only 1\ inches. This quantity, indeed, might be 

 expected to be small, from our knowledge of the fact that, three or four degrees 

 to the south, the country is nearly rainless.'' 



* These figures, however startling, are not overstated. On Sunday, Decem- 

 ber 11th, 1854, at Hi A.M., the thermometer indicated a temperature of 99o, 

 and the dew-point fell to 350; the wind, during that state of the atmosphere, 

 blowing in strong gusts from the north. On December 13th, at 4 P.M., the 



» Miller, Phil. Trans. 1851, p. 155. ^ Phil Trans. 1850, p. 354, 

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