NARRATIVE OF THE CRUISE. 267 



been mistaken. Whither can they go, and by what means can they find their way back ? 

 The question with regard to birds that fly is difficult enough, but it may always be sup- 

 posed that they steer their course by landmarks seen at great distances from great 

 heights, or that they follow definite lines of land. In the present case the birds can 

 have absolutely no landmarks, since from sea level Tristan da Cunha is not visible from 

 any great distance ; the birds cannot move through the water with anything approaching 

 the velocity of birds of flight ; they have, however, the advantage of a constant presence 

 of food. The question of the aquatic migration of Penguins and Seals seems a special one, 

 and presents difficulties quite different from that of the migration of birds of flight. The 

 Penguins certainly do not go to the Cape of Good Hope nor to St. Helena. 



Although there is little fresh water on Nightingale Island, one pond was observed in 

 the rookery, but the water was undrinkable. In a cave near the landing-place also, there 

 was a scanty trickling spring of excellent water filling a small basin ; water enough to keep 

 three or four persons alive might be got here. On a small open patch in the centre 

 of the rookery, free from Tussock, was found a bed of a yellow-flowered Composite plant, 

 which has since been determined as a new species of Cotula (Cotula moseleyi), as far 

 as yet known peculiar to Nightingale Island. A representative of the genus (Cot n In 

 [Leptindla] plumosa) is, however, abundant in Kerguelen Island and in the Antarctic 

 region generally. 



With the exception of the Journal and Meteorological Eegister of Lieutenant Eich, for 

 the four months he was Commandant of the garrison in 1816, no regular record of the 

 weather has been kept at the Tristan group of islands. This is much to be regretted, for, 

 lying as these islands do far south in the Atlantic, in the immediate track of vessels 

 bound to Australia and the Cape of Good Hope, and midway between that Cape and Cape 

 Horn, a register of the weather here would be of the utmost importance, and the Eev. 

 W. F. Taylor would have conferred a great boon on seamen had he devoted a small 

 portion of his time, during his five years' residence at Tristan, to keeping a daily record 

 of meteorological phenomena. 



From the description of some of the more intelligent of the inhabitants of Tristan 

 Island, and from the remarks of vessels visiting the group and cruising in its vicinity, more 

 especially from the notes of some of the captains of H.M. ships in the early part of this 

 century, a fair idea can be given of the average state of the weather throughout the year. 



The prevailing winds are westerly, strong breezes being the rule, and light winds or 

 calms the exceptions. In the winter months the wind is usually northward of west, and 

 in the summer months southward. August, September, and October are the worst months 

 of the year, and it is then no unusual thing for gales to continue for a fortnight at a 

 stretch. December to March is the fine season ; and in January and February rollers 

 are frequent, so that landing is sometimes impossible. Easterly gales are rare, but are 



