144 Mr Lawson on the Trade-Winds at Barhadoes. 



vary according to circumstances. All these modifications I 

 found to be exhibited at Barbadoes with much regularity by 

 the trade-winds, though, from the nature of the subject, a 

 perfect confoi-mity was not to be looked for. 



23. Wherever the inner margin of the trade- winds rests 

 upon the sea, it is obvious that a considerable portion of the 

 air, as it ascends the atmosphere, must still retain its tendency 

 to the formation of an easterly breeze, and will accordingly 

 give rise to a returning current from the SE. (21) to the 

 northward of the equator, and from the NE. to the southward 

 of it. As, during the summer and autumn, the equatorial 

 margin of the trade to the eastward of Barbadoes was over 

 the open sea, traces of this breeze were then visible almost 

 every day. Its influence is very commonly experienced along 

 the outer margin of the trade-winds, when its elevated tem- 

 perature, and high dew-point, unequivocally indicate the 

 locality from which it came. 



24. Instances in which the wind gradually drew from NE. 

 to the southward of E., as the sun or moon passed the meridian, 

 wore common enough ; but the change occasionally occurred 

 without the agency of any such cause. On the 24th Septem- 

 ber 1841, for instance, the wind at Barbadoes was from ENE. 

 all day. The sun's declination was about 1° S., the moon's 

 hour of transit 7'^ 47'" VSi., and her declination then 21° S. 

 At 2 A.M. on the 25th, it commenced to blow hard, with heavy 

 squalls from NE. and continued so for a considerable time. 

 By 6 A.M. the wind was SE. and fresh, the lower clouds 

 (cumuli) moving from the same point, and above them some 

 ciiTo-strati from the northward. The wind continued from SE. 

 during most of the day, but gradually diminished in force ; at 

 9 P.M. there was a slight breeze from ENE. On this occasion, 

 though the strong breeze from the northward at 2 A.M. may 

 fairly be ascribed to the attraction of the moon on passing the 

 meridian with a high southern declination, assisted by that 

 of the sun passing the lower a few hours afterwards, still the 

 wind had veered to the SE. before the moon passed the lower 

 meridian, and, consequently, before the atti*action could have 

 operated efficiently in changing its direction. Now, it is clear, 

 that, if the trade-wind over any portion of the earth's surface 



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