SURVEYS. 



15 



all directions, and thus afforded the means of obtaining satisfactory 

 results, in a measure independent of atmospheric influences. The 

 state of the atmosphere, as to pressure, temperature, moisture, and 

 wind, was carefully noted, and duly recorded during the continuance 

 of the experiments. 



Mr. W. C. Bond, and his son, Mr. George Bond, the distinguished 

 astronomers of Harvard University, kindly offered their aid, and re- 

 corded the observations upon the time-cylinder connected with the 

 observatory clock at Cambridge. To these gentlemen, and to Mr. 

 Moses G. Farmer, Telegraphic Engineer, and his assistants, I feel 

 greatly indebted for the aid they rendered me in operating with the 

 Telegraphs. I would also make mention of the obliging manner in 

 which the different Telegraph Companies placed their wires and appa- 

 ratus at my disposal. 



LATITUDES. 



The latitudes of all the principal stations have been obtained by cir- 

 cummeridian observations of the sun and stars, with the repeating 

 circle ; at the minor stations generally by equal altitudes with the 

 sextant and artificial horizon. The headlands, capes, &c, which have 

 not been observed at, are deduced by triangulation from two or more 

 stations where observations were made : these different determina- 

 tions are distinguished by appropriate marks in the tables, 



LONGITUDES. 



The longitudes of the principal stations have been determined by a 

 series of observations of moon-culminating stars, east and west of the 

 moon. In order to carry out these views, application was made to the 

 Hon. Secretary of the Navy, to appoint Wra. Cranch Bond, Esq.,* at 

 Dorchester, near Boston, to make a regular series of observations on 

 the moon-culminating stars, at his private observatory, during the 

 absence of the Expedition. Directions were also given to Lieut. James 

 M. Gillis, of the Navy, who succeeded me at the Naval Depot, to 

 observe a similar series at Washington. From these arrangements, the 

 Expedition derived most important aid in the determinations of the 

 absolute longitudes where the observatories were established. Very 



* Since the Astronomer of Harvard University. 



