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IX, — On the influence of Sun-heated Land in producing 

 Ascending Atmospheric Currents, 



By Mr. Thos. Hopkins. 



[Rtad April 6tt, 1863.] 



The Hadleyan theory of the trade winds is founded upon 

 the supposed influence of the rarefaction of the atmosphere 

 of the torrid zone by the direct action of solar heat. The 

 Rev. T. Milner, in his recent work called the Gallery of 

 Nature, gives this explanation of that theory ; he says — 

 "As the sun is always vertical at some place within the 

 tropics, the average temperature in that region is much 

 higher than in latitudes to the north and south, and the 

 incumbent air is thereby rarefied and expanded. The con- 

 sequence is, that, in obedience to hydrostatic laws, masses of 

 air are continually buoyed up from the surface, or swelled 

 round the torrid zone in the form of a protuberant belt, the 

 upper strata flowing over and running off in streams north 

 and south towards the poles, where, having been cooled and 

 condensed, they descend and flow over the surface towards the 

 equator, pouring in a perpetual current of air to supply the 

 place of that forced up by the heat of the tropics." — (p. 440.) 

 And such is, in substance, the theory of winds which is 

 found in all modern books that treat on Meteorology. Yet 

 this theory is not only unsupported by facts, but directly 

 at variance with many of them, — nearly the whole of those 

 known having a bearing on the subject tending to show, not 

 the truth, but the falsity of the theory. That the surface of 



