OCEANIC CIRCULATION. 253 



beyond the region of the trade-winds^ say between 20 

 and 40 north latitude ; and (2) that there is an enor 

 mous rainfall in the region of equatorial calms, which 

 Sir John Herschel attributes to the deposit of waters 

 taken up by the N.E. and S.E. trades. To this I must 

 reply that in my essay on Eain in the Intellectual 

 Observer for December 1867, I have weighed the 

 whole question of rainfall at least with great care, and 

 with constant reference to the best sources of informa 

 tion. One circumstance I there note which seems at a 

 first view (or rather viewed as Dr. Carpenter appears to 

 consider the matter) much more fatal as an objection 

 to my theory than either of those noted by Dr. Car 

 penter ; viz., that according to the observations of 

 Humboldt and others, the annual rainfall is at a maxi 

 mum at the equator, and diminishes with increase of 

 latitude. But the whole question is, where does all 

 this rain come from ? If it comes from tropical and 

 equatorial evaporation it will surely not be argued that 

 what falls in or near the place of evaporation itself, 

 represents the total amount of such evaporation. It is 

 unquestionable, I conceive, that the rainfall is only the 

 excess of the aqueous vapour poured so copiously into 

 the air from the whole of this region. It is the quan 

 tity which the air, as it were, rejects. It is a matter of 

 little importance where the rainfall of higher latitudes 

 comes from, though it should be noticed that the views 

 of Dove, Kaemtz, and other leading meteorologists re 

 specting the winds and rains of high and low latitudes, 

 support my remark about the great rivers. 



