NARRATIVE OF THE CRUISE. 



241 



extent of the two smaller islands had not been ascertained. As the Challenger completed 

 the exploration of the group, it appears desirable to give an exact account of it here, 

 compded partly from old publications 1 and partly from these more recent observations. 



Tristan Island, the northernmost, largest, and highest island of the group, has a 

 nearly circular form, with the apex 7640 feet above the level of the sea in its middle ; in 

 fact, if a circle with a radius of 3| miles be described, using the summit of the island as a 

 centre, the circumference of the circle will be found to touch the salient points all 



Fk;. 98.— The Island of Tristan da C'unlia. 



round, except in one part, viz., in the eastern quadrant, where the coast will be found 

 to project half a mile beyond the circumference. 



Precipitous cliffs, 1000 to 2000 feet in height, rise directly from the sea everywhere, 

 except in the northwest quadrant, where there is, in front of the cliffs, an irregular 

 flat, 100 to 200 feet above the sea level, 1\ miles in length and half a mile in breadth. 

 From the top of the high cliffs the island has the appearance of rising gradually on all 



1 Nautical Magazine, vols, iii., iv., viii., xxii. (185.3), xxv. (1856), xxxi. (1862) ; MorrelPs Voyage of the "Antarctic " ; 

 Account of Tristan da Cunha, by the Rev. W. F. Taylor, 1856 ; Voyage of H.M.S. " Galatea," 1867 ; Parliamentary 

 Paper*), 1876; and Documents in the Hyilrograi>hic Department. 



(nakr. chall. exp. — vol. i. — 1884.) 31 



