63 



longitude, as from a great number of materials, 

 which I have with some difficulty collected. As 

 a considerable body of water cools with extreme 

 slowness, it is sufficient to plunge the thermo- 

 meter into a bucket of water just taken from the 

 surface of the ocean. Though this experiment 

 is very simple, it has been hitherto singularly 

 neglected. In the greater part of the narrations 

 of voyages, the temperature of the ocean is but 

 casually mentioned ; for instance, on occasion 

 of the researches made on the cold that prevails 

 at great depths, or on the stream of warm water 

 that traverses the Atlantic. I have not been 

 able to make use of the excellent work of Mr. 

 Kir wan on climates, because this celebrated na- 

 turalist has not sufficiently distinguished, in his 

 tables of the temperature of the different lati- 

 tudes, between what is the result of direct expe- 

 riments, and what of theory ; but the second 

 voyage to the straits of Magellan % under the 

 command of Churruca and Galeano, the relation 

 of Abbe Chappes Voyage to California, the work 

 published at Philadelphia under the title of 

 Thermometrical Navigation -}~, and particularly 

 the interesting experiments made in 1800 by 

 Mr. Perrins, on board the Skelton, in the course 



* Bon Cosme de Churruca, Apendice del Viage al Magel- 

 iaues, 1793, p. 98. 



t Therraometrical Navigation, 1799, p. 37. 



