46G 



EXPEDITION TO POINT BARROW, ALASKA. 



meridian the piano of detorsion read 164 30', and by turning the torsion circle 90 first backward,* 

 next forward, and again to the first position, we have the readings : 



Mean deflection o = 83'.l for /J = 90; hence - = - K - =0.01563, and the scale value o=l'.016 



j 5310.9 



The fixed mirror was set to show scale division 50 bisected, and at O 1 ' 08 m (September 10) a. in., 

 Gottingen mean time, the magnetometer (movable mirror) was set to read 524. 



(2) On November 1, 4 h 52 m p. m., Gottingeu time, both mirrors set to read 500. 



(3) The instrument was readjusted November 3, 6 h 10 m p. in. At 3 h 47 m p. in. the plane of de- 

 torsion was found to read 51 52', when the following observations were made : 



Mean deflection a = 104'.3 for/3 = 90 ; hence- = 1* L3 =0.01970, and the new scale value a = l'.020 



j &29S.7 



Fixed mirror reads 500, and the magnetometer (movable mirror) was set to 493 at 5' 1 1C" 1 a. in., 

 November 4, Gottiugen time. Increasing scale divisions denote increasing easterly declination. 



* The circle is graduated from left to right. 



