CHARLES WILKES. 363 



city after a few weeks' absence, your paper of the 

 15th of May, containing some remarks on the errors 

 existing in the charts of the northwest coast of 

 California, by Colonel Benton, was brought to my 

 notice. Although I have no desire to detract from 

 any one, yet I think it due to others, as well as to 

 the United States Exploring Expedition, to place 

 the following facts before the public respecting the 

 errors which did exist in the longitude of this coast, 

 the i discovery' of which is now claimed to have been 

 first made, and the errors corrected, by Colonel 

 Fremont, through a series of astronomical observa- 

 tions across the continent. 



" Shortly after the publication of Vancouver's 

 charts in 1798, errors were suspected to exist in 

 them, (his points were determined by lunar observa- 

 tions and several chronometers, which latter per- 

 formed but indifferently ; and from these his results 

 were obtained,) from a difference which was found 

 between him and the Spanish surveying-vessels 

 employed at the same time on the coast of Califor- 

 nia. The amount of error was not, however, truly 

 ascertained until some years after this, when Captain 

 Beechey, of H.B.M. ship the Blossom, visited this 

 coast in 1826. His observations were confirmed by 

 Captain Sir Edward Belcher, in H.B.M. surveying- 

 ship the Sulphur, in 1835; and it was again cou- 



