ANNOTATIONS AND ADDITIONS. 33 



ANNOTATIONS AND ADDITIONS. 



( l ) p. 3. " On the Chimborazo, 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 opportunities of observing in the Pacific), being 

 carried there by the force of the wind when storms come 

 off the land. In the same involuntary manner insects are 

 transported into the upper regions of the atmosphere, 

 16000 or 19000 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 excellent chemist who, as Professor at the newly insti- 

 tuted 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 Rivero, a phenomenon affording 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 summit of the Silla, which is 5400 (5755 E.) feet 

 high, and then sink down towards the neighbouring sea 

 coast. These movements continued uninterruptedly for the , 



VOL. II. D 



