F. GEOGRAPHY. 247 



and ethnology as the more important interests of the sur- 

 vey would warrant. 



All the important harbors were visited, and the latitude, 

 longitude, and magnetic variation of each determined, one 

 line extending from Attn, on the west, through the Aleutian 

 Islands to the Shumagins, on the east. The magnetic varia- 

 tion was found to be 2 30' less easterly than it was when 

 the last previous observations were taken, some twenty or 

 thirty years ago ; in some instances the difference amounted 

 to 6. In one case the positions were more than twelve 

 miles <yut on the charts. 



Deep-sea soundings were taken at intervals north of the 

 islands, developing a very unexpected depth of water west 

 of the Unalashka, in one instance 1100 fathoms being reached 

 without touching the bottom within less than twenty miles 

 from the shore. The southwest termination of the shallow 

 plateau of Behring Sea was determined to be at the north- 

 west end of Unalashka, where the bottom suddenly drops 

 from 60 to over 800 fathoms. The soundings put an entirely 

 new complexion on the western part of Behring Sea, and jus- 

 tify the suggestion advanced in 1869 that there is a deep-sea 

 valley in that part of this sea. At a depth of 800 fathoms 

 the deposition of globigerina ooze, or recent chalk, was found 

 going on, as it is in the North Atlantic. 



Temperature and current observations were constantly 

 made, which confirm the deductions from the observations in 

 1871" and 1872. N"o well-defined or constant current exists 

 in the east or middle portions of Behring Sea. The tides are 

 every where compound and irregular, and always rise from 

 the east toward the west, pouring in with the flood into 

 Behring Sea, while there is but little efflux with the ebb. 

 All the harbors were examined for a place suitable for land- 

 ing the telegraph cable, but only one w^as found which of- 

 fered the required facilities. This was on the island of Great 

 Kyska, and was thoroughly sounded and surveyed. A new 

 and very good anchorage was found on the island of Adakh. 

 Nearly all the prominent peaks on the various islands were 

 measured. Particular attention was given to the volcanic 

 island of BogosloiF. This was found to be much farther 

 north and east than it has been placed on the charts; and 

 800 fathoms of water were found on the line of the supposed 



