ANNOTATIONS AND ADDITIONS. 247 



ANNOTATIONS AND ADDITIONS. 



(*) p. 227. " On the Chiniborazo, eight thousand feet higher than 



Etna'' 



Small singing birds, and even butterflies, are found at sea at 

 great distances from the coast (as I have several times had opportu- 

 nities of observing in the Pacific), being carried there by the force 

 of the wind when storms come off the land. In the same involun- 

 tary manner insects are transported into the upper regions of the 

 atmosphere, 16,000 or 19,000 feet above the plains. The heated 

 crust of the earth occasions an ascending vertical current of air, by 

 which light bodies are borne upwards. M. Boussingault, an ex- 

 cellent chemist, who, as Professor at the newly instituted Mining 

 Academy at Santa Fe de Bogota, visited the Gneiss Mountains of 

 Caraccas, in ascending to the summit of the Silla witnessed, together 

 with his companion Don Mariano de Bivero, a phenomenon afford- 

 ing a remarkable ocular demonstration of the fact of a vertically 

 ascending current. They saw in the middle of the day, about noon, 

 whitish, shining bodies rise from the valley of Caraccas to the sum- 

 mit of the Silla, which is 5400 (5755 E.) feet high, and then sink 

 down towards the neighboring sea coast. These movements con- 

 tinued uninterruptedly for the space of an hour, and the objects, 

 which at first were mistaken for a flock of small birds, proved to be 

 small agglomerations of straws or blades of grass. Boussingault 

 sent me some of the straws, which were immediately recognized by 

 Professor Kunth for a species of Vilfa, a genus which, together 

 with Agrostis, is very abundant in the provinces of Caraccas and 

 Cumana : it was the Vilfa tenacissima of our Synopsis Plantarum 

 sequinoctialium Orbis Novi, t. i. p. 205. Saussure found butterflies 

 on Mont Blanc, as did B-amond in the solitudes which surround the 

 summit of the Mont Perdu. When Bonpland, Carlos Montufar, 



