177^' THE PACIFIC OCEAN. 109 



thrive on so burnt-up a soil. When broken, which 

 is easily done, the quantity of juice is very great ; 

 and it might be supposed that, when dried, it would 

 shrivel to nothing ; yet it is a pretty tough, though 

 soft and light wood. The people here believe its 

 juice to be so caustic as to erode the skin*: but I 

 convinced them, though with much difficulty, to the 

 contrary, by trusting my ringer into the plant full of 

 it, without afterwards wiping it off. They break 

 down the bushes of euphorbia, and suffering them to 

 dry, carry them home for fuel. I met with nothing 

 else growing there, but two or three small shrubs, 

 and a few fig-trees near the bottom of the valley. 



" The basis of the hills is a heavy, compact, blueish 

 stone, mixed with some shining particles ; and, on 

 the surface, large masses of red friable earth, or 

 stone, are scattered about. I also often found the 

 same substance disposed in thick strata; and the little 

 earth, strewed here and there, was a blackish mould. 

 There were likewise some pieces of slag ; one of which, 

 from its weight and smooth surface, seemed almost 

 wholly metalline. 



" The mouldering state of these hills is, doubtless, 

 owing to the perpetual action of the sun, which 

 calcines their surface. This mouldered part being 

 afterwards washed away by the heavy rains, perhaps 

 is the cause of their sides being so uneven. For, as 

 the different substances of which they are composed, 

 are more or less easily affected by the sun's heat, 

 they will be carried away in the like proportions. 

 Hence, perhaps, the tops of the hills, being of the 

 hardest rock, have stood, while the other parts on a 

 declivity have been destroyed. As I have usually 

 observed, that the tops of most mountains that are 

 covered with trees have a more uniform appearance, 



* Glas, p. 231., speaking of this plant, says, that he cannot 

 imagine xnhy the natives of the Canaries do not extract the juice, and 

 use it instead of pitch, for the bottoms of their boats. We now learn 

 from Mr. Anderson their reason for not using it. 



