xriii INTRODUCTORY CHAPTER 



gray ; the breast white ; eyes large, and the bill moderately 

 long. In its nature it is rather shy ; and as it does not seem to 

 possess those powers of flight which could have brought it from 

 America or Africa, it seems, therefore, not unreasonable to con- 

 clude, that it is indigenous to the island. If so, it may be con- 

 sidered as an additional fact, favourable to the conjecture that 

 St. Helena is a fragment of a larger island. 



I have already mentioned, upon the authority of Captain 

 Heywood, who commanded his Majesty's ship Nereus, that the 

 indigenous gum-wood trees of St. Helena are the same as on 

 Tristan d'Acunha and Gough's Island. It would be of impor- 

 tance to ascertain with accuracy this fact ; and whether the wire- 

 bird be also a native of those islands, and of Ascension and 

 Saxemberg. If all these points should be verified, trifling as they 

 may appear, they would be important to the cause of geology. 



The mountainous ridge which divides the island by its greatest 

 length, appears chiefly to consist of indurated clay, in some parts 

 surmounted, and in others mixed, with shattered rock ; which, 

 being of a brittle nature and easily broken, has never been per- 

 fected into solid stone. This clay may possibly appear to be the 

 material which composes the greater part of the stones found on 

 the island. It has no visible intermixture of sand, and is not 

 tenacious, but friable. It is easily excavated in the form of 

 buildings, with interior upright walls; and in this manner it is 

 wsed for cait sheds, &c. 



Towards the western extremity, within a mile of the coast, the 

 ridge assumes a different appearance: it is there very abrupt, 

 and craggy, on the south, and slopes gently to the north : here 

 are solid rocks, from which large fragments have been detached 

 and lie scattered on the surface. The most remarkable of these 

 are at the west extreme of the ridge ; where a great number. 



