UO OBSBKVATIONS ON THE WINDS. 



20° N. and 25° to 30° W. ; between 18° and 20°, 40 per cent, of the wind 

 observations are from East, or some point to the Southward of East. It 

 seems most probable that this remarkable difference in the direction of the 

 wind is caused by the Cape Verde Islands, though it is difficult to say why 

 they should not have a similar effect in some other month. The N.E. Trade 

 has decidedly increased in force since November. Considering the number 

 of wind observations in each Square, the percentage of gusty and puffy 

 winds is much greater in Square 40 than in Square 39. Between 

 16° and 17° N. and 34° and 85° W. there were heavy squalls without either 

 clouds or rain. Fine weather winds, and squally winds having a force 7 

 or upwards, are more common in Square 40 than in 39. 



The S.E. Trade prevails to 4° N. It has very decidedly decreased in 

 force since November. 



Conclusion. — The N.E. Trade sometimes seems to draw round the Coast 

 of Africa in the same way that water does round a rock, whilst the current 

 arrows show that the sea has a similar motion. The Trade gets weakest 

 in that part of the sea where the difference of temperature of both air and 

 sea is greatest, which is contrary to the theory of some meteorologists. 

 Sometimes it seems to blow from hot towards cooler air, as shown in the 

 diagrams of October and November. The remarkable clear-weather gusts 

 experienced in Square 40 have been remarked upon in the course of the 

 Paper as probably downward rushes of air. 



The " Eemarks on Wind " show that both the N.E. and S.E. Trades 

 are often more Easterly in direction and weaker in force during the night 

 than during the day. 



Attention has been called to the fact that in December, the commence- 

 ment of the Harmattan season, the N.E. Trade is diverted into an East 

 wind on the Western side of the Cape Verde Islands, whilst to the East- 

 ward of them it blows from N.N.E. It has also been shovra that during 

 the Southern winter the wind and weather near Cape St. Eoque are much 

 more unsettled than they are in parts of the sea in the same latitude, but 

 farther East ; also that the wind becomes very Southerly near the South 

 American Coast, whilst in the Southern summer it is very Northerly. 



N. B. — It should be clearly understood that whilst the diagrams only 

 show the wind from that point of the compass which has the largest number 

 of observations, a great variety of other winds blow in those parts where 

 the two Trades meet, especially in the atmospherical eddy which curves 

 round the South- Western part of North Africa; into it the Northern verge 

 of the S.E. Trade is drawn as a light South-Westerly wind, where it meets 

 the Southern verge of the N.E. Trade drawn into a N.W. wind, and the 

 result of their meeting is the greatest confusion of light airs, calms, squalls, 

 rain, thunder, and lightning of the most awful kind, together with water- 

 spouts, &c., &c. 



To the foregoing general remarks the following, respecting particular 

 localities within the scope of the N.E. Trade Wind, are added. Further 

 application of them will occur in the Section on Passages, and other remarks 

 will be found in Section JIJ. 



