1872.] The Origin of the Great Cyclones. 429 
trade would be able to generate acyclone ; but the existence 
of such an upper current in the cyclone region is not esta- 
blished by safe observations. The Peak of Teneriffe is near 
the African coast, and under the influence of the North- 
African monsoon. It is near the parallel of 28° N. lat. and 
15° W. long., while the West-Indian hurricane region is in 
10° to 15° N. lat. and 60° W. long. The sea-dust observed 
off the coast of Africa, when examined by the great German 
microscopist, Ehrenberg, was distin€tly pronounced by him 
full of ‘‘ South-American Infusoria ;’* the same was true of 
all the blood-rains and sea-dust of the Cape Verde Islands, 
Lyons, Genoa, and other places, showing a southerly or 
S.W. current in the high atmosphere, not from Africa, but 
from South America, and, as Prof. Eastman says in his 
little publication (p. 15, 5th clause), ‘‘ If a mass of air from 
the return trade-wind, moving from the S.W., be precipitated 
into the N.E. trade-wind, it will meet with equal opposition 
along its whole front, and there will be no tendency to a rotatory 
or cyclonical motion.” 
On the r&th of July, when Prof. Dové’s easterly current 
from over Africa should have been blowing, the astronomer 
on the Peak writes :—‘‘ Long we gazed at the novel upper 
clouds sailing over our heads from the south-west” (!) “‘ and 
having moved his station to Alta Vista, 10,700 feet high, on 
the 25th of August,” he went down to Orotar on business, 
and ‘‘ leaving the station with a south-west breeze, changed 
it, at an altitude of 6,700 feet, to a north-east. Returning 
again on the 30th, he experienced a similar change at about 
the same height, the strength of the wind increasing as he 
ascended. Arrived at the station, the south-west wind was 
found to be blowing with great violence, and it so continued 
to blow for more than a fortnight, when, as the winter 
seemed to have set in, the party quitted the mountain.”t 
Here we see, by the very testimony Prof. Dové depends 
upon, in the very midst of the ‘‘ hurricane season” in the 
tropics, when his fancied easterly wind should have been in 
full blast, Piazzi Smyth found only a south-west wind. 
There is no evidence of an easterly wind except the long- 
disputed dust of Ehrenberg. 
If the stratum of the regular N.E. trade-wind is, in Cen- 
tral America (what Piazzi Smyth, as we have just seen, 
found it to be at Teneriffe), 6,700 feet deep (and it is proba- 
bly three or four times as deep), it is easy enough to see how 
* See EHRENBERG’s Passat Stanb und Blut Regen. 
+ See Piazzi SMyTn’s Teneriffe, p. 113. 
