139 



coralline and by the numerous holes made in it either by the 

 action of the sea or excavated for the sake of obtaining the 

 stone, and these make baths of the most brilliantly clear 

 water.* The breadth opposite Pernambuco varies from thirty 

 to sixty yards, and it there affords ample breadth for a delight- 

 ful and interesting walk in the cool fresh breezes of a tropical 

 evening, and one to which I have frequently resorted. On 

 the one side you have the endless roll and thunder of the vast 

 Atlantic, and on the other the lake-like stillness of the har- 

 bour, in which vessels from all parts of the world are lying 

 secure and in a state of repose, which makes a curious contrast 

 to the noise and fury going on within a few yards of them. 

 At spring tides the Eeef is entirely covered to the depth of 

 a foot or more, but at neap tides the upper part is as much 

 out of the water, and in no place that I have observed does it 

 rise above the level of spring tides. This, I think, is a very 

 strong proof against Darwin's theory that it was a bar of sand 

 and pebbles, first consobdated and then elevated, because in that 

 case it is quite unlikely that the action which raised it would 

 have been so uniform as to have produced such a reef as now 

 exists. I have a strong opinion that the reef was once uni- 

 formly regidar, and that the breaks in its present outbne 

 being lower in some places than other are occasioned by the 

 breaches the sea has made in it. Dr. Gardner's idea that it 

 owes its origin to the decay of the rock between it and the 

 shore, illustrating it by the example near Rio Forinoso, I 

 venture to think is likewise untenable, because, except the 

 reef itself, there are only a very few points on the coast of the 

 Brazils where any real sandstone rock exists, the shore being 

 composed either of loose shifting sand hills, similar to those 

 on the New Brighton and Formby coast, though on a much 

 larger scale, or else it is of granitic character. 



From numerous and careful observations which I had the 



I iliink I uever saw water to wliicli this term mixl'i be so truly applied. 



