TAHITI. 5 



proper contains the best, and therefore engrosses all the commerce. It 

 has in consequence been for many years the seat of government. 



The whole island is of volcanic formation, but there is no longer 

 any active igneous action, nor is there any well-defined crater to be 

 seen. Coral reefs, with occasional openings, are attached to the 

 shores, and the larger island (Tahiti) has also a sea reef. Between 

 the two reefs is an almost continuous channel for boat navigation, 

 and on the northern side they enclose many safe and commodious 

 harbours for shipping. On this side also vessels may pass from 

 harbour to harbour, within the outer reef. This reef varies in 

 breadth from a few yards to fifty, or even an hundred. The shore 

 that adjoins the coral reef is formed of black volcanic sand, occa- 

 sionally mixed with comminuted shells, which give it a grayish hue. 

 Basaltic ridges reach the sea at intervals, and form projecting points 

 of moderate elevation. 



We began without delay to overhaul the vessels, and the few sick 

 persons we had on board were sent on shore to a shed hired for the 

 purpose on Point Venus. 



An observatory was established at the same place, and furnished 

 with both astronomic and magnetic instruments; and as soon as the 

 repairs of the vessels had made such progress as to permit it, parties 

 were formed for the survey of the four principal harbours and the 

 channels between them. These harbours, Matavai, Poapoa, Toanoa, 

 and Papieti, are so important to the many whale-ships which visit 

 this island, that I felt it an imperative duty to obtain accurate charts 

 of them all. At the same time, a large party of officers and natu- 

 ralists was ordered to cross the island, to reach, if possible, Orohena, 

 one of the highest peaks, and to visit Lake Waiherea. 



I had been in hopes of obtaining a full series of moon culminating 

 stars on Point Venus ; but I was disappointed, for it rained almost 

 every night. I was, therefore, compelled to rely for the longitude on 

 the chronometers alone, and restricted even in that method to obser- 

 vations of the sun. I was, however, well pleased to find that my 

 results differed from the best preceding authorities no more than 1' 

 33" of space. These authorities give 149° 29' 43" W., for the longi- 

 tude of Point Venus. 



The mountains were obscured by clouds during the whole time of 

 my stay, and no angles could be taken for the measurement of their 

 heights, nor could the party I detached for the purpose reach their 

 summits ; but the Peacock remained for some days after my depar- 



