APPENDIX. 421 



4th. The observations required to be made with the sympiesometer 

 half-hourly, on ascending the heights ; the temperature of all springs ; 

 the temperature of all the different heights, in the sun and shade ; 

 morning and evening, at noon, 9 a. m., 9 p. m., 3 p. m, and 9 a. m. ; their 

 watches will be set to ship's time, in order that the observations may 

 be compared. 



5th. As many observations relative to the topography of the island 

 as may be in their power ; the dimensions of the lake on the moun- 

 tains, its altitude, and, if any opportunity offers of getting at its depth, 

 to ascertain that also. 



6th. The meridian altitude, or that of double altitudes for latitude. 



7th. Any peculiar or remarkable atmospheric phenomenon, such as 

 refraction, &c, will be sketched, and the time of appearance noted ; 

 the other observations will be made at the same time. 



(Signed) Charles Wilkes, 



Commanding- Exploring Expedition. 

 U. S. Ship Vincennes, 



Matavai Bay, September 13th. 



III. 



U. S. Ship Vincennes, 



Matavai Bay, September 19th, 1839. 

 Sir, — 



You will proceed with the Porpoise under your command, to the 

 west end of Nairsa, Dean's, or Prince of Wales's Island, in longitude 

 148° 02' W., and latitude 15° 05' 30" S. You will measure the dis- 

 tance from this point to Krusenstern's Island, both by your log and 

 chronometer observations. 



You will circumnavigate Krusenstern's Island, and ascertain the 

 latitude and longitude of its eastern and western points ; thence to the 

 small island which you saw before, carefully ascertaining its distance 

 from Krusenstern's ; after which you will proceed westerly, to search 

 for Lazareff Island, said to be in latitude 14° 56' S., longitude 149° 

 10' 00" W. I am disposed to believe, from our examinations, that 

 Krusenstern's Island may have been taken for a part of Dean's Island ; 

 that a passage of a few miles may exist, dividing what we now believe 

 to be Krusenstern's Island ; if such exist, it is at its western extremity. 



From thence you will proceed along the parallel of latitude 15° 30' 

 S., and keep a good look-out for Recreation and Fugitive Islands, laid 

 down on Arrowsmith's Chart, and until you have passed the longitude 

 of 165° W. There is a reef and island supposed to exist in about 161° 

 W. ; this ground you will well examine. 



2L 



