Prevailing Currents of the Atmosphere. 303 
in the equatorial region. Aided by successive emendations, 
this theory continues to receive the general sanction of the scien- 
tific world. 
It isnot my design, in this communication, to discuss theories. 
But the facts and results which I have delineated on the accom- 
panying maps,* indicate courses of circulation in the atmosphere 
which are nearly and mainly horizontal; while the common the- 
ory alleges a course or circuit of circulation, in each hemisphere, 
which is essentially vertical, the warm air being supposed to as- 
cend near the equator to great elevations and there flow outwards, 
to supply the inward current from the higher latitudes; the obli- 
quity from a north and south direction being of course due to the 
earth’s rotation. I propose, therefore, to state in a summary way, 
some of the facts and considerations which, in my own view, 
serve to invalidate this calorific theory. 
1. The specific difference of mean temperature in the inter- 
tropical winds as compared with equal zones of extratropical 
winds, is inadequate and wholly disproportioned to the dynamical 
effects which are exhibited in these winds. Jam not aware that 
any successful attempt has been made to prove the converse of 
this objection. 
2. The rising of the whole body of the trade wind in the 
equatorial latitudes, in the manner alleged, has never been con- 
firmed by observation; and, as I apprehend, may safely be deni- 
ed. Nor has any proof of the fact been offered, other than infer- 
ences drawn from common but very limited phenomena, which 
I think may be explained in a more satisfactory manner. 
3. The perpetual snow line of the Andes has been found near 
one thousand feet higher in 16° to 18° south latitude than at the 
equator, or on the parallel of the equatorial calms of the Atlantic. 
This fact, in a region so favorable to an equable development of 
natural influences, I deem to be wholly conclusive against the 
theory. 
A. The semiannual change, to the north and south, of the local- 
ity of the trade winds and the belt of equatorial calms, which re- 
sults from the change of seasons, bears no adequate proportion to 
* Those lost in the Peacock. 
t See the observations of Mr. Pentland in the Journal of the London Geograph- 
ical Society. Also, Penny Cyclopedia, Vol. VII, Art. Cuimate. 
