130 BULLETIN OF THE 



Our adopted value, therefore, of the geographical position of the 

 Astronomical Station of the U. S. Coast and Geodetjc Survey at 

 Plover Bay, Eastern Siberia, is 



Latitude, 64 22' 00" ± 6" N. 



j-173 21 32 ±6 J 



Longitude, 1 h. m. s. s. V W. Gr. 



(11 33 26.1 d= 0.4 J 



One station was marked by driving a piece of whale's rib into 

 the ground and piling rocks around it. Being identical with the 

 station of Lieut. Onatsevich, any one visiting the place will by the 

 aid of that chart readily identify it. 



Having completed our investigation of the geographical position 

 of Plover Bay, we proceed to detail our observations for the longi- 

 tude of the boundary. 



The Yukon arrived at Plover Bay at ten in the evening of 

 August 11, 1880. The following day was cloudy in the morning, 

 afterward rained, and later partially cleared up so that we obtained 

 two pairs of equal altitudes of the sun for time, the interval being 

 about three hours. During the afternoon we succeeded in getting 

 four sets of six each of double altitudes of the sun for time. From 

 the equal altitudes the time of local mean noon by the chronom- 

 eter, was llh. 18m. 13.9s, and from the double altitude it was llh. 

 18m. 14.2s., a very satisfactory agreement. By means of the in- 

 tervals the probable errors of each of these determinations have 

 been made out. For the equal altitudes it is ± 1.7s, and for the 

 double altitudes it is ± 0.30s, values which may be taken as fairly 

 representative of the different conditions under which the obser- 

 vations were made. From these observations the corrections of 

 our chronometers to Greenwich mean time on August 12 were 

 determined. 



On August 14, we sailed from Plover Bay to the eastward and 

 northward, cruising along the Arctic coast as far as Point Belcher, 

 and returning thence passed through Behring Strait to Port Clar- 

 ence, and afterwards returning to Behring Strait made a landing 

 on the southeastern shore of Ratmanoff, or the Big Diomede Island, 

 on September 10. We came to anchor at seven in the morning, 

 about a mile off shore, and sailed away about three in the after- 

 noon. During our stay observations were made for latitude and 

 time, and all the magnetic elements, declination, dip and intensity. 

 Of time observations three sets of six each of double altitudes of 



