448 Mr. J. K. Laugh ton on the Permanent and Periodic Winds. 



at Ega in the same months ; and the river reaches its highest 

 level about the first week in June, the waters being then about 

 45 feet above their lowest level. Higher up still, the air would 

 seem to attain a state of saturation, unknown in any other coun- 

 try. " It was impossible (Bates says) at S. Paulo to keep salt 

 for many days in a solid state. . . . Six degrees further west- 

 ward, namely at the foot of the Andes, the dampness of the 

 climate of the Amazonian forest region appears to reach its 

 acme ; for Poeppig found at Chincao that the most refined sugar 

 in a few days dissolved into syrup." 



On the other hand, on the east side of the Atlantic both 

 northerly and southerly trades are most clearly drawn into 

 Equatorial Africa, a country whose humid climate has proved so 

 fatal to many of our countrymen; and in India we find the 

 south-west monsoon pointing, in the same way, to the violent and 

 heavy rains of the wet season. 



The following Table of the rainfall at a few places in the loca- 

 lities I have named will not be uninteresting, as showing in 

 figures the excessive nature of the precipitation to which I re- 

 fer:— 





Yearly fall, in 

 inches. 



Remarks. 



Doldrums of the Atlantic 



224-6 



229-2 



280 



189-6 



1175 



242 1 



175-2 



610-3 



110-3 



254 



263 



116-3 



Estimated by Maury. 



Keith Johnstone. 

 >> 



Dr. Ives. 

 Kaemtz. 





San Luis de Maranhao 





Mean of peninsula of Hindostan 

 Mean of North-east Provinces... 

 Mean of West Ghauts 



Cherrapongi (N.E.) 





Mahabuleshwar 



Uttray Mullay 







Such figures tell their own tale : the elastic force of the aqueous 

 vapour in the tropical atmosphere may be stated, in round num- 

 bers, as equivalent to 1 inch of mercury; and the sudden re- 

 moval by precipitation of a very large proportion of this weight 

 necessarily disturbs equilibrium. Where such a lessening of the 

 weight of the atmospheric column takes place, air from the 

 heavier columns of the neighbourhood must stream in, and that 

 with a force bearing some proportion to the suddenness of the 

 cause ; so that when this cause is both sudden in point of time 

 and comparatively confined in point of space, the effect becomes 

 very clearly marked. 



Mr. Thomas Hopkins some years ago, in an Essay on " The 



