30 RIO DE JANEIRO chap. 



the formation which Humboldt designates 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 appear- 

 ance. 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 atmosphere of 

 the northern sloping bank, they were immediately redissolved. 



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

 beginning of winter, was delightful. The mean temperature, 

 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 Corco- 

 vado, the sound produced by the drops pattering on the countless 

 multitude of leaves was very remarkable ; 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 performers than in Europe. A small frog, of the genus 

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

 of the water, and sends forth a pleasing chirp : when several 

 are together they sing in harmony on different notes. I had 

 some difficulty in catching a specimen of this frog. The genus 

 Hyla has its toes terminated by small suckers ; and I found 

 this animal could crawl up a pane of glass, when placed abso- 



