28G 



HYDROGRAPHY. 



north side is a bare reef, on which the sea breaks. No natives were 

 seen on this island, and there is believed to be no permanent inhabi- 

 tants, for it has not wherewithal to sustain life. 



ASSUMPTION AND GEIGAN ISLAND, WITH THE MANGS. 



Grigan lies to the south of Assumption, the northern island of the 

 Marian or Ladrones. It is high, and makes from the northeast in 

 the shape of a dome. As vessels generally pass between it and 

 Assumption, I was desirous of fixing their true positions, and that of 

 the Mang Eocks. According to Freycinet, the Mangs lie in the 

 channel between them ; but we found the Mangs to lie to the north- 

 ward of Assumption, 20 miles. The north end of Grigan we made in 

 latitude 18° 48' north, and longitude 145° 50' east. It was my inten- 

 tion to have sought a harbor on the west side of the Island of Grigan, 

 to obtain water, and make it a magnetical station, but my time did 

 not permit of the delay. The distance between Grigan and Assump- 

 tion Island is 50 miles ; this space is entirely clear. Assumption we 

 place in 19° 43' 30" north, and longitude 144° 48' east. Its height 

 above the sea was determined to be 2090 feet. 



When passing this group it is advisable for vessels to keep a middle 

 course between Grigan and Assumption, by which they will not be 

 subject to be becalmed, as would be the case by a near approach to 

 either of these islands. The Marian Islands seem to intercept the 

 course of the easterly winds, which prevail with steadiness from the 

 eastward to their meridian, but after passing them vary to the south- 

 ward and westward, and become uncertain. 



COPPER ISLAND. 



The Copper Island of west longitude, as before remarked, was sought 

 for unsuccessfully. The charts place the position of the one of eastern 

 longitude in 20° 05' north, and 131° 50' east. In this position it does 

 not exist, for we passed directly over the place, in fine weather, and 

 had a most favorable opportunity for the search, with a smooth sea 

 and very clear horizon ; but nothing like land or indications of it were 

 to be seen. 



