26 Captain Sabine's Experiments on the 



Hammerfest, June 16, 1823. On the sea-beach at Fugleness, Th. 42° : 

 Needle 3 . - . . 614". 2 



Needle 4 . . . 609". 2 



Needle 5 . • . . 605". 2 



Needle 6 . . . 613". 6 



Mean . 610". 5 



Spitzbergen, July 17, 1823. On the Inner Norway Island, Th. 36°: 

 Needle 3 . . . 723". 9 



Needle 4 . . . 722". 6 



Needle 5 . . . 718". 7 



Needle 6 . . . . 715". 5 



Mean . 720". 2 



Greenland, August 21, 1823. On the Pendulum Islands, Th. 38° : 

 Needle 3 . . . 691". 2 



Needle 4 . . . 690". 3 



Needle 6 . ; . 687". 7 



Mean .* 689". 7 



Drontheim, October 21, 1823. On the ascent of the Steinberget Hill, 

 Th. 47°: 



Needle 3 569". 4 



Needle 4 . . ' 577". 3 



Needle 6 . . ' . 570". 7 



Mean . 5 72". 5 



These are the times of horizontal vibration, the squares of 

 which express the proportion which that part of the magnetic 

 force bears at each station, which gives the compass-needle its 

 direction in regard to the geographical meridian. To obtain 

 from thence the total magnetic intensity, if T' be the time 

 of horizontal vibration, D the dip, and T" the time of corre- 

 sponding vibration in the direction of the dipping needle ; 

 T" s= /V 8 cos. D : and T" 2 will express the ratio of the 

 total magnetic force at each station. 



