THE VOYAGE OF THE BEAGLE 99 



beneath the well-known mountain of the Corcovado. It has 

 been remarked, with much truth, that abruptly conical hills 

 are characteristic of the formation which Humboldt desig- 

 nates as gneiss-granite. Nothing can be more striking than 

 the effect of these huge rounded masses of naked rock rising 

 out of the most luxuriant vegetation. 



I was often interested by watching the clouds, which, 

 rolling in from seaward, formed a bank just beneath the 

 highest point of the Corcovado. This mountain, like most 

 others, when thus partly veiled, appeared to rise to a far 

 prouder elevation than its real height of 2300 feet. Mr. 

 Daniell has observed, in his meteorological essays, that a 

 cloud sometimes appears fixed on a mountain summit, while 

 the wind continues to blow over it. The same phenomenon 

 here presented a slightly different appearance. In this case 

 the cloud was clearly seen to curl over, and rapidly pass 

 by the summit, and yet was neither diminished nor increased 

 in size. The sun was setting, and a gentle southerly breeze, 

 striking against the southern side of the rock, mingled its 

 current with the colder air above; and the vapour was thus 

 condensed; but as the light wreaths of cloud passed over 

 the ridge, and came within the influence of the warmer atmos- 

 phere of the northern sloping bank, they were immediately 

 re-dissolved. 



The climate, during the months of May and June, or the 

 beginning of winter, was delightful. The mean tempera- 

 ture, from observations taken at nine o'clock, both morning 

 and evening, was only 72. It often rained heavily, but 

 the drying southerly winds soon again rendered the walks 

 pleasant. One morning, in the course of six hours, 1.6 inches 

 of rain fell. As this storm passed over the forests which 

 surround the Corcovado, the sound produced by the drops 

 pattering on the countless multitude of leaves was very re- 

 markable, it could be heard at the distance of a quarter of a 

 mile, and was like the rushing of a great body of water. 

 After the hotter days, it was delicious to sit quietly in the 

 garden and watch the evening pass into night. Nature, in 

 these climes, chooses her vocalists from more humble per- 

 formers than in Europe. A small frog, of the genus Hyla, 

 sits on a blade of grass about an inch above the surface of 



