306 Mr. Redfield on the 
successive series of laminated or stratified currents, overlapping 
and moving upon each other in like series of subordinate circuits, 
the major axes of which, in the northern sammer, are principally 
found in the calms of the horse latitudes. 
The calms and light winds which are peculiar to this last 
mentioned region in summer, result not so much from any general 
suspension of the aerial movements, as from the absence of that 
brisk relative motion which commonly prevails in other latitudes. 
For, the predominating movements of the atmosphere being ei- 
ther from the east or west, in conformity with the law of the 
earth’s rotation,. and there being little movement of the surface 
winds in these directions along the parallels in which lie the axes 
of atmospheric revolution, it follows, that only the more sluggish 
northerly and southerly winds chiefly prevail on these parallels, 
in mid ocean, at this season. And I may here suggest, thata 
like explanation is mainly applicable to the calms of fie equa- 
torial region, both between the regular trades, and the Indian 
monsoons. 
Towards the eastern borders of a basin of revolution, such as 
the North Atlantic, there appears to be less of sluggishness in the 
aerial currents which move to or from the lower latitudes; which 
here appear more clearly defined and more strongly developed, 
and hence are more readily traced in their course; as is seen in 
the northerly winds which gradually merge in the N. E. trades, 
in the region between Madeira and the Canaries, and thence to 
the tropic. While, near the western borders of the Atlantic and 
over the adjacent coasts of America, the opposite southerly and 
southwesterly winds of the circuit are often well developed at 
the earth’s surface, at least in the warm season. Like character- 
istics pertain to the system of winds in like latitudes, in other 
circuits of atmospheric revolution, in different oceans. 
That the N. E. trade winds have not sooner been traced in 
their horizontal curves into the southwest winds, may be owing 
in part to the frequent overlying of the southwesterly upon the 
easterly winds, which occurs mostly towards the exterior por- 
tion of the trades; and partly, to a neglect to inquire into the 
_ actual and successively varying directions of the trade winds, in 
the central and western parts of the ocean basins, in the inter- 
tropical latitudes. In these latitudes, in the regions here men- 
rs tioned, the N. E. trade winds are more often found nearly at east, 
