376 Ml* Lawson on the Trade-Winds of Barbadoes. 



server, owing to the peculiar deflections they undergo, and 

 which have been described above (57, 62) ; and the barometer 

 attains its minimum in the interval between the central 

 margins of the NW. and SW. currents, because, there, from 

 the same cause (65), the SW. current is also absent, but no 

 sooner does the latter reach him than the pressure begins to 

 increase and the barometer regains its ordinary elevation. 

 Were the observer anywhere in the triangular space 

 ACE, Fig. 2, he would perceive a fall of the barometer 

 without any thing remarkable in the wind at first, as ex- 

 plained above (58). It is not to be supposed that all these 

 complicated phenomena occur with the regularity here men- 

 tioned, but, though subject to variation, the principle re- 

 mains the same. 



68. The immense quantity of rain that falls during a hur- 

 ricane, and the enormous amount of electricity developed, 

 have led some authors to suppose that either, or both of 

 these, were mainly instrumental in producing the storm, in- 

 stead of being effects merely, of the disturbance of the at- 

 mospheric currents when nearly saturated with vapour. 



69. The dew-point is usually high during the hurricane 

 months in the West Indies, and when the free movement of 

 the atmospheric currents is checked, it often attains the 

 height of 75° or 76° Fahr., while the temperature of the air 

 at the same time may not exceed 78° or 80°. Under such 

 circumstances, the sky, towards noon, often becomes over- 

 cast, and, I think, I never saw, even in winter, in this coun- 

 try, more gloomy and dismal weather than may not unfre- 

 quently be seen at Barbadoes at mid-day, in August or Sep- 

 tember. The immense mass of vapour necessary to obscure 

 so completely the rays of a vertical sun, could only be pro- 

 duced in a bed of the atmosphere of great thickness, satu- 

 rated with moisture. That much rain falls under such cir- 

 cumstances is not astonishing, but their frequent occurrence, 

 in the localities most subject to hurricanes, without pro- 

 ducing any upward current, as maintained by Mr Espy, is 

 certainly strong evidence against the correctness of his 

 theory. 



70. The justness of these views is strikingly illustrated by 



