ILLUSTRATIONS AND ADDITIONS. 



(1) p. 210 " On the Chimborazo, upwards of eight thousand 

 feet higher than Etna" 



SMALL singing birds, and even butterflies, (as I have 

 myself witnessed in the Pacific,) are often met with at 

 great distances from the shore, during storms blowing off 

 land. In a similar manner insects are involuntarily carried 

 into the higher regions of the atmosphere, to an eleva- 

 tion of 17,000 to 19,000 feet above the plains. The light 

 bodies of these insects are borne upwards by the ver- 

 tically ascending currents of air caused by the heated con- 

 dition of the earth's surface. M. Boussingault, an admirable 

 chemist, who ascended the Gneiss Mountains of Caracas, while- 

 holding the appointment of Professor in the newly established 

 Mining Academy at Santa Fe de Bogota, witnessed, during 

 his ascent to the summit of the Silla, a phenomenon which 

 confirmed in a most remarkable manner this vertical ascent 

 of air. He and his companion, Don Mariano de Rivero, 

 observed at noon a number of luminous whitish bodies rise 

 from the valley of Caracas to the summit of the Silla, an 

 elevation of 5755 feet, and then sink towards the adjacent 

 sea coast. This phenomenon was uninterruptedly prolonged 

 for a whole hour, when it was discovered that the bodies, at 

 first mistaken for a flock of small birds, were a number of 

 minute balls of grass-haums. Boussingault sent me some 

 of this grass, which was immediately recognised by Pro- 

 fessor Kunth as a species of Vilfa, a genus of grass which 

 together with Agrostis is of frequent occurrence in the 

 provinces of Caracas and Cumana. It was the Vilfa tenacis- 

 sima of our Synopsis Plantarum CBquinoctialium Orbis Novi^ 

 t. i. p. 205. Saussure found butterflies on Mont Blanc, and 

 Ramond observed them in the solitudes around the summit 

 of Mont Perdu. When MM. Bonpland, Carlos Montufar r 

 and myself, on the 23rd of June, 1802, ascended the eastern 

 declivity of Mount Chimborazo, to a height of 19,286 feet, 

 and where the barometer had fallen to 14' 84 inches, we found 

 winged insects buzzing around us. We recognised them to 



