porter's journal. 3& 



fresh current of air, called the sea-breeze, rushes towards 

 the land to supply the vacuum. Every where throughout 

 the world, where the sun's rays are felt, this elevation of 

 atmosphere, in a more or less degree, takes place, but not 

 so much as to produce land winds, except within the tro- 

 pics, and this elevation is always greatly increased by the 

 opposition of land to the sun's rays. The change in the 

 temperature of the earth cannot, as has been supposed, 

 produce this extraordinary elevation of the atmosphere. 

 Was the heat of the sun absorbed by the earth, the effect, in- 

 stead of being heightened, would be lessened. The ele- 

 vating effects produced by the earth on the atmosphere, may 

 be attributed to reflection alone, and the current of air, 

 called the land-breeze, is owing entirely to the earth's 

 form. An extensive flat country without mountains, would 

 produce, by reflection, a great elevation of atmosphere ; 

 but when the sun, the cause of this elevation, was remo- 

 ved, little or no land-breeze would ensue, for the waift of 

 mountains to change the course of the atmosphere from its 

 vertical direction. A great rise and fall of the atmo^lSerej 

 in the like manner, takes place at sea at a great distance 

 from coasts, but owing to the smooth surface of the oceaii 

 and the absence of mountains, we are rendered insensible 

 of it. 



On the 1 8th discovered a sail ; and this being the first 

 we had discovered since the capture of the Nocton, it ex- 

 cited great interest among the ship's company. On ap- 

 proaching her, discovered her to be a brig under Portu- 

 guese colours, standing towards St. Salvadore ; as I did not 

 wish to make ourselves known to her, hoisted English co- 

 lours and stood on our course. 



On the 20th, spoke a Portuguese vessel from St. Salva- 

 dore, bound to Laguira, out eighteen days. We boarded 

 her under English colours, and on the captain's coming on 

 board, he informed me that an Enghsh sloop of war had j 

 put into St. Salvadore in distress a short time before he 

 sailed, laden with specie, from Rio de la Plata, last from 

 Rio Janeiro, and bound to Europe. From the description 

 he gave me of this vessel, there can be no doubt of her be- 

 ing his Britannic majesty's sloop of war the Bonne Citoy- 

 enne, of which we obtained intelligence by the Nocton* 

 The prisoners informed me that she sailed six days before 



