FAEE^VELL LETTEKS. 31 



sail for Cuba, in company witli the Alcudia, the packet- 

 boat of the month of May, which had been detained by 

 an English fleet, then blockading the port in order to cut 

 off the communication between Spain and her colonies. 

 They concluded to follow his advice, and arrangements 

 were made to receive their instruments on board the 

 Pizarro. Don Eaphael ordered the captain to stop at 

 Teneriffe, as long as Humboldt should deem necessary, 

 that the travellers might visit the port of Orotava, and 

 ascend the peak. 



It was ten days before their instruments were em- 

 barked and the vessel was ready to sail. They spent 

 that time in preparing the plants that they had collected 

 in the beautiful valleys of Galicia, which they were the 

 first naturalists to explore, and in examining the fuci and 

 mollusca, which the northwest winds had cast on the 

 rocks. Crossing from Corunna to Ferrol, a little town 

 on the other point of the bay, they made several experi- 

 ments on the temperature of the ocean, by means of a 

 valved thermometrical sounding lead, and found that 

 the neighborhood of a sand bank is revealed before the 

 lead can be made use of, by the quick decrease in the 

 temperature of the water, and that the seaman can there- 

 fore perceive the approach of danger much sooner by 

 the thermometer than by the lead. 



The time of departure drawing near Humboldt wrote 

 farewell letters to his friends in Germany and Paris. 

 As before leaving Paris he had agreed with Captain 

 Baudin, that if the expedition for discoveries in the 

 Pacific, which seemed to be adjourned for several years, 

 should take place at an earlier period, he would endeavor 

 to return from Algiers and join it, at some port in 



