APPENDIX. 445 



2d. Lieutenant Emmons will provide himself with a pocket sex- 

 tant, artificial horizon, and pocket azimuth, compass, note-book, &c. 



3d. Dr. Guillou will provide himself with two thermometers and an 

 hygrometer. 



4th. The observations recniired 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 

 distance 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° 



VOL. II. 112 



