OB ROYAL GARDENS. 183 



A part of these so-styled gardens is indeed beautiful ; 

 the voyager sees the scene change every moment, and tho 

 verdure of some of the islands appears the more lovely 

 from its contrast with chains of rocks, displaying only 

 white and barren sands. The surface of these sands, 

 heated by the rays of the sun, seems to be undulating like the 

 surface of a liquid. The contact of layers of air of unequal 

 temperature, produces the most varied phenomena of sus- 

 pension and mirage, from ten in the morning till four in 

 the afternoon. Even in those desert places the sun ani- 

 mates the landscape, and gives mobility to the sandy plain, 

 to the trunks of trees, and to the rocks that project into 

 the sea like promontories. When the sun appears, these 

 inert masses seem suspended in air ; and on the neighbour- 

 ing beach, the sands present the appearance of a sheet of 

 water gently agitated by the winds. A train of clouds 

 suffices to seat the trunks of trees and the suspended rocks 

 again on the soil ; to render the undulating surface of the 

 plains motionless ; and to dissipate the charm which the 

 Arabian, Persian, and Hindoo poets have celebrated as " the 

 sweet illusions of the solitary desert." 



We doubled Cape Matahambre very slowly. The chro- 

 nometer of Louis Berthoud having kept time accurately at 

 the Havannah, I availed myself of this occasion to deter- 

 mine, on this and the following days, the positions of Cayo 

 de Don Cristoval, Cayo Flamenco, Cayo de Diego Perez, 

 and Cayo de Piedras. I also employed myself in examining 

 the influence which the changes at the Dottom of the sea 

 produce on its temperature at the surface. Sheltered by 

 so many islands, the surface is calm as a lake of fresh water, 

 and the layers of different depths being distinct and sepa- 

 rate, the smallest change indicated by the lead, acts on the 

 thermometer. I was surprised to see that on the east of 

 the little Cayo de Don Cristoval, the high banks are only 

 distinguished by the milky colour of the water, like the 

 bank of Vibora, south of Jamaica, and many other banks, 

 the existence of which I ascertained by means of the ther- 

 mometer. The bottom of the rock of Batabano is a sand 

 composed of coral detritus ; it nourishes sea-weeds which 

 fly ever appear on the surface : the water, as I have 

 already observed, is greenish ; and the absence of the milky 



