GEOGRAPHICAL POSITIONS. 



409 



the charts from unnecessary names. In many cases, the determina- 

 tions of the positions by the discoverers have been so erroneous, that 

 the names only are left to confuse and mislead ; the positions assigned 

 them have been frequently examined, without any vestiges of land or 

 dangers of any kind being found. 



The plan I adopted was to divide the whole area of the Pacific into 

 triangles; at their angles to make the best series of astronomical ob- 

 servations, for latitude and longitude, which lay in our power, and our 

 time would permit ; these were the initial points : the meridian distances 

 were measured by chronometers, passing and repassing between them 

 and the minor points, by which means the determination of the initial 

 points were compared one with another. 



The shortest elapsed time between all points has been used, to avoid 

 the liability to accumulations of errors from rate, although the chro- 

 nometers performed well. The observations, at the initial stations, 

 to avoid error, have been several times calculated by different methods, 

 as upon these positions all the others would depend; those at the 

 minor points were made, when possible, on shore. Should any of them 

 hereafter receive determinations more reliable than our record will 

 show, it will only be necessary to add or subtract the difference to the 

 stations with which they are connected. 



In some cases we differ materially from those who have preceded 

 us, but in others the differences are small, resulting probably from the 

 manner in which the positions have been determined. 



In a previous part of this volume I have mentioned that, at my 

 suggestion, the Hon. Secretary of the Navy appointed Mr. William C. 

 Bond, of Dorchester, Massachusetts, since the distinguished observer, 

 astronomer, and Director of the Observatory at Cambridge, and Lieut. 

 James Gillis, of the Navy, who succeeded me in charge of the Depot 

 at Washington, to make a continuous series of observations on the 

 Moon Culminating Stars, during the absence of the Expedition ; from 

 these, as well as those calculated for Greenwich, contained in the Nau- 

 tical Almanac, our longitudes have been determined. Those from 

 actual observations at Greenwich are marked with an asterisk, and 

 the results are embraced in the following tables. Table I shows the 

 longitudes of Dorchester, Cambridge, and Washington, determined from 

 the corresponding observations. Table II, the observations made at 

 the initial stations for longitude and latitude. 



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