132 BULLETIN OF THE 



For the longitude of our station upon the Big Diomede Island 

 we have, therefore, as follows : 



Plover Bay 1880, Aug. 12, noon Chron'r corr'n determined, ± 1.7 s. 



Big Diomede Id., " Sept. 10, 8.g/i. a. m., " " ±0.35 



Plover Bay " " 12, midnight " " ±0.15 



By means of the time determinations of August 12 and Septem- 

 ber 12, the rates of the chronometers are determined and then the 

 Greenwich time determination at Big Diomede Island, September 

 10, is made to depend upon the determination at Plover Bay, Sep- 

 tember 12, and the rates of all the chronometers carried back to 

 September 10, a period of 2.64 days. 



The resulting longitude by each chronometer is shown in the fol- 

 lowing table : 



Chronometer No. 2535 was our " hack," and 311 a sidereal chro- 

 nometer used in making comparisons. Each had rather large rates, 

 that of 2535 exceeding nine seconds, and that of 311 jive seconds 

 per day. The indiscriminate mean of all is \lh. 16m. 17.4s. As- 

 signing only half weight to chronometer 2535, the longitude resul- 

 ting is 



h. m. s. 



II 16 17.7 



The probable error of the Greenwich time at the Diomedes, based 

 upon the agreement of the chronometer is ± 0.36s. 



For the probable error of the longitude, therefore, we have 



Probable error of longitude of Plover Bay = ± 0.39 s. 



Probable error local time determination, Plover Bay, Sept. 12 = ± 0.15 



Probable error local time determination, Diomedes, Sept. 10 == ± 0.35 



Probable error Greenwich time determination, Diomedes, Sept. io.= ± 0.36 



h. m. s. s. 



Resulting longitude adopted, 11 16 17.7 ± 0.65. 



The astronomical station of the United States Coast and Geodetic 



