MAGNETISM AND CIRCULATION OF THE ATMOSPHERE. IQS 
winds discharge into the equatorial calm belt continues to go 
south, as an upper current bound for the calms of Capricorn. 
But what should cause this wind to cross over ? "Why should there 
not be a general mingling in this calm belt of the air brought by 
the two trade-winds, and why should not that which the southeast 
winds convey there be left, after its ascent, to flow off either to 
the north or to the south, as chance directs ? 
175. In the first place, it was at variance with my belief in the 
grand design ; for I could not bring myself to believe that the 
operations of such an important machine as the atmosphere should 
be left to chance, even for a moment. Yet I knew of no agent 
which should guide the wind across these calm belts, and lead it 
out always on the side opposite to that on which it entered ; nev- 
ertheless, certain circumstances seemed to indicate that such a 
crossing does take place. 
176. Evidence in favor of it seemed to be afforded by this cir- 
cumstance, viz., our researches enabled us to trace from the belt 
of calms, near the tropic of Cancer, which extends entirely across 
the seas, an efilux of air both to the north and to the south ; from 
the south side of this belt the air flows in a never-ceasing breeze, 
called the northeast trade-winds, toward the equator. (Plate I.) 
On the north side of it, the prevailing winds come from it also, 
but they go toward the northeast. They are the well-known 
southwesterly winds which prevail along the route from this 
country to England, in the ratio of two to one. But why should 
we suppose a crossing to take place here ? 
177. We suppose so, because these last-named winds are going 
from a warmer to a colder climate ; and therefore it may be in- 
ferred that nature exacts from them what we know she exacts 
from the air under similar circumstances, but on a smaller scale, 
before our eyes, viz., more precipitation than evaporation. 
178. But where, it may be asked, does the vapor which these 
winds carry along, for the replenishing of the whole extra-tropical 
regions of the north, come from ? They did not get it as they 
came along in the upper regions, a counter-current to the north- 
east trades. They did not get it from the surface of the sea in 
the calm belt of Cancer, for they did not tarry long enough there 
to become saturated with moisture. Thus circumstances again 
pointed to the southeast trade-wind regions as the place of supply. 
