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 j 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. 



