134 Mr Lawson on the Trade- Winds at Barbadoes. 



quii'es a northern declination, the temperature of the sea in- 

 creasing, the equatorial limit o£ the NE. trade is gradually 

 removed to the north, leaving the coast to the south-east of 

 Trinidad almost entirely from April or May to October, and 

 becoming weaker and more irregular on that to the westward 

 of and around it. 



4. The equatorial limit of the NE. trade is found to vary 

 considerably in the open sea in the different months of the 

 year, while that of the SE. trade alters much less. The fol- 

 lowing table, taken from a more extended one in Horsburgh's 

 East India Navigator, gives the mean position of the equatorial 

 limits of the trades between longitude 18° and 26° W., every 

 second month of the year : — 



Month. 



February, 



April, 



June, 



August, 



October, 



December, 



The individual results for each month seem to have varied 

 from the corresponding mean about 2° each way, an explana- 

 tion of which will be attempted hereafter. 



5. The temperature of the sea, on either side of the equator, 

 alters very considerably with the sun's changes in declination. 

 This is well shewn by the following observations made on 

 board the French frigate L'Hermionc, in a voyage to and from 

 Rio Janeiro in 1816. The frigate crossed the line on the 

 16th May outward, and again on the 11th October, homeward- 

 bound, and in both cases near the meridians laid down for the 

 above table. The temperatures of the surface of the sea were, on 



Lat. North. Long. West. Temp, of Sea. 



Outer Limit of 



NE. Trade. 

 Inner Limit of 



NE. Trade. 

 Inner Limit of 



SE. Trade. 

 Oiittr Limit of 



SE, Trade * 



* Annales de Chiinie, &c., tome iv., pp. 411-17. 



