304 ISLANDS DISCOVERED 



Wallis of these islands, is not in the least appli- 

 cable to the Kutusoff*s islands ; and even supposing 

 that this were the case, such a supposition could 

 only be certain if a mistake of two degrees and a 

 half, in Wallis's longitude of the Pescadores, were to 

 be allowed. But I believe I shall be able to prove 

 that the longitude of Captain Wallis cannot be in- 

 correct by half a degree, or even by a quarter of a 

 degree. East and west of the Pescadores are two 

 points, with the situation of which we are ac- 

 quainted by very exact observations, but which 

 hav^e likewise been determined by Wallis, by lunar 

 observations j the true longitude of these points 

 can, therefore, serve to prove the value of the lunar 

 observations made on board the Dolphin. These 

 points are the islands of Boscawen and Keppell, 

 and the island of Tinian. 



1. The 14th of August, I767, the islands of Bos- 

 cawen and Keppell were seen from the Dolphin ; the 

 16th the ship was 1° 3' west of them, and from the 

 lunar distances measured that day, Mr. Wales, the 

 astronomer, calculated the longitude of Boscawen 

 Island 174" 7' 39", and that of Keppell Island 

 174° 10' 24". La Pey rouse determined the longi- 

 tude of the two islands at 173° 56' W. Taking it 

 for granted that the longitude fixed by La Peyrouse 

 is the true one, the error in the longitude determin- 

 ed by the Dolphin is less than a quarter of a degree. 



2. The longitude of Tinian was determined by 

 four series of lunar observations : two series of 



