274 Proximate Causes of certain Winds and Storms. 



nionlh of April, found a wind from the south-west rersmbling the 

 cold blustering winds of March, in New England.* On the Peak 

 of TenerifFe, Humboldt, Von Buch, and others, have encountered a 

 raging west wind which scarcely allowed Humboldt to keep his feet. 

 This was in summer. In the winter this west wind descends to the 

 coast. f These facts show that the currents of the upper atmos- 

 phere are strictly counter currents, which carry eastward the air the 

 trade winds have carried westward. They do not seem to be a mere 

 result of motion of the air of the equatorial regions towards the pole, 

 but of a gyratory movement in a vertical plane. 



(c.) On Monday the 27th of April, 1812, the SoufTrier mountain on 

 the island of St. Vincent, after having remained dormant for more 

 than a century, suddenly emitted a column of smoke which continued 

 to increase in magnitude and density until Thursday, the 30th, when 

 it was accompanied with an appearance of flames and an eruption of 

 lava. On Friday, the 1st of May, the atmosphere of Barbadoes was 

 darkened by clouds of volcanic sand and ashes, which descended 

 upon the island to the depth of nearly three quarters of an inch. 

 Barbadoes hes at the distance of from ninety to one hundred miles 

 east of St. Vincent, and the trade wind blows so directly and violent- 

 ly from the former towards the latter island, that a passage from St. 

 Vincent to Barbadoes, can be effected only by making a circuit of 

 many hundred miles. Von Buch remarks that " by this striking oc- 

 currence, the returning current in the upper regions was proved, and 

 with it the theory of the trade winds, for which we are indebted to 

 Hadley, was become something more than conjecture. 



It places the existence of the upper current beyond the reach of 

 a doubt, but lends probability to the theory of Halley rather than to 

 that of Hadley, which last supposes the upper current to be directed 

 from the equator towards the poles. In the present instance its 

 course was due east. It is well known that the under current is de- 

 flected from its course by islands and projecting shores, but it is not 

 easy to see why Hadley's upper current should be similarly affected. 

 I cannot help suspecting that a vortex had established itself with one 

 extremity on Barbadoes, and the other on St. Vincent, and that the 



* See this Journal, Vol. xl, p. 4. 



t See Von Buch on the climate of the Canary Islands, in Jameson's Journal for 

 July, 1826. 



