MEXICO AND THE UNITED STATES. 335 



climate. Barometric measurements of height were taken by 

 Humboldt at frequent intervals along this ill-constructed road, 

 cut through almost impenetrable forests of oak and fir, and the 

 results of these labours were afterwards employed as a basis for 

 laying down the line for a new high road. On February 7, 

 1804, the travellers made the ascent of Cofre, a mountain in 

 the neighbourhood of Perote, the height of which exceeds that 

 of the Peak of Tenerifle by 1,063 feet. Trigonometric mea- 

 surements were also taken by Humboldt of the volcano of 

 Orizaba. 



Thus employed in scientific investigations of various kinds, 

 the travellers prosecuted their journey, until they at length 

 reached the goal of their wanderings, and entered the town of 

 Vera Cruz, the harbour of which is the centre of European 

 commerce, in the West Indies. The town is situated in an arid 

 plain, with neither river nor running stream in its vicinity. 

 From this port they embarked on board a royal frigate on 

 March 7, 1804, for Havana, to take possession of the collec- 

 tions left for safe keeping in the year 1 800, and to complete 

 the data they had gathered in Mexico, for the treatise upon 

 which Humboldt was engaged, entitled, ' Essai politique sur 

 1'Ile de Cuba.' 



After a sojourn of nearly two months at Havana, Humboldt 

 set sail for the United States, on April 29, accompanied by 

 Bonpland and Carlos Montufar. In the Channel of Bahamas, 

 they encountered a severe storm, which lasted seven days ; but 

 Humboldt and his companions were mercifully preserved 

 through every danger, and after a voyage of twenty days they 

 arrived safely in the harbour of Philadelphia. 



A welcome, as courteous as that which had been accorded 

 to Humboldt by the viceroy at Mexico, awaited him from 

 Jefferson, the President of the United States, from whom he 

 received the following invitation to visit Washington : 



< Washington : May 28, 1804. 



6 Sir, I received last night your favour of the 24th, and 

 offer you my congratulations on your arrival here in good 

 health after a tour in the course of which you have been 

 exposed to so many hardships and hazards. The countries you 



