RED FOGS AND SEA DUST. 
CHAPTER IV. 
EED FOGS AND SEA DUST. 
Where found, ^ 157. — Tallies on the Wind, 158. — Where taken up, 160. — Hum- 
boldt's Description, 163.— Information derived from Sea Dust, 165. — Its Bearings 
upon the Theory of Atmospherical Circulation, 167. — Suggests Magnetic Agency, 
170. 
157. Seamen tell us of "red fogs" which they sometimes en- 
counter, especially in the vicinity of the Cape de Verd Islands. 
In other.parts of the sea also they meet showers of dust. What 
these showers precipitate in the Mediterranean is called " sirocco 
dust," and in other parts "African dust," because the winds which 
accompany them are supposed to come from the Sirocco desert, 
or some other parched land of the continent of Africa. It is of a 
brick-red or cinnamon color, and it sometimes comes down in such 
quantities as to cover the sails and rigging, though the vessel may 
be hundreds of miles from the land. 
Now the patient reader, who has had the heart to follow me in 
the preceding chapters around with " the wind in his circuits," 
will perceive that proof is yet wanting to establish it as a fact 
that the northeast and southeast trades, after meeting and rising 
up in the equatorial calms, do cross over and take the tracks rep- 
resented by C and G, Plate I. 
Statements, and reasons, and arguments enough have already 
been made and adduced to make it highly probable, according to 
human reasoning, that such is the case ; and though the theoret- 
ical deductions showing such to be the case be never so good, pos- 
itive proof that they are true can not fail to be received with de- 
light and satisfaction. 
Were it possible to take a portion of this air, as it travels down 
the southeast trades, representing the general course of atmos- 
pherical circulation, and to put a tally on it by which we could 
always recognize it again, then we might hope actually to prove, 
by evidence the most positive, the channels through which the air 
of the trade-winds, after ascending at the equator, returns whence 
it came. 
G 
