64 



of a voyage from London to Bombay, have fur- 

 nished me with numerous materials for my work. 



Employed at Lima in researches on the tem- 

 perature of the sea, I had engaged an officer of 

 the royal navy, Mr. Quevedo, to observe day by 

 day, during his passage from Peru to Spain, 

 round Cape Horn, the heights of two thermome- 

 ters, one of which should be exposed to the air, 

 and the other plunged into the upper stratum of 

 the ocean. The observations made by Mr. 

 Quevedo in 1802 on board the frigate Santa 

 Rufina, which will be given in this work, em- 

 brace both temperatures, from the sixth degree 

 of south to the thirty-sixth of north latitude ; and 

 are so much the more valuable, as this very well 

 informed navigator knew perfectly his longitude 

 by means of a chronometer by Brockbanks, and 

 of the distances of the moon from the sun. 

 His meteorological instruments, constructed by 

 Nairne, had been compared, before his depar- 

 ture, with those I made use of on the Cordil- 

 leras. 



From the equator to the twenty-fifth and 

 twenty-eighth degrees of north latitude, the tem« 

 perature is remarkably constant, notwithstand- 

 ing the difference of the meridians ; it is more 

 variable in the high latitudes, where the melting 

 of the polar ice, the currents caused by this melt- 

 ing, and the extreme obliquity of the solar rays 



* Nicholson's Journal, 1804, p. 131. 



