82 



RECORD AND RESULTS OP 



stations near the pole, may reach magnitudes sufficient even to overpower the regular 

 solar diurnal progression. 



It Avill be observed that at Port Foulke the motion of the north end of the needle 

 from early morning till about one hour after noon, is westerly, magnetically, though 

 in reality it is easterly, as the needle points south of west. 



For the sake of illustration we will suppose an observer stationed at the magnetic 

 pole near King WiUiam Island, and two needles placed in his meridian, one north 

 the other south of him, also two needles placed in his parallel, one east the other 

 west ; these needles wiU. point with their north or marked end towards him when 

 in their normal position (which, for instance, always happens some hours before 

 noon), but early in the morning, upon turning successively to them he will find 

 them all deviating to his left, and an hour or two after noon he wiU find them 

 deflected to his right ; they have all moved in the interval from left to right, though 

 in reality the marked end of the northern needle moved from west to east, that of 

 the southern needle from east to west, and that of the eastern from north to south, 

 and of the western from south to north ; however, the motion of the eastern needle 

 appears earlier, and that of the western later, by the amount of their diff"erence of 

 longitude with that of the observers, the motion being governed everywhere by 

 local solar time. 



The declinometer was also observed nearly every day at 8 A. M. and 2 and 10 

 P.M., between November 12, 1860, and March 9, 1861. There are, however, 

 several interruptions, and the instrument has been moved in the interval. The only 

 use I propose to make of this series is to ascertain the angular motion of the mag- 

 net between 2 and 10 P. M., and to form from it an estimate of the diurnal range. 







Declinometer Record at Poi 



t Foulke. 



Scale 



Readin 



gs. 







I860. 



2 P. M. 



10 P.M. 



1860. 



2 P.M. 



10 P.M. 



1860. 



2 P. M. 



10 P.M. 



1861. 



2 P.M. 



lOP.M 



Nov. 12 



38.8 



40.0 



Dec. 21 



33.5 



36.3 



Jan. 16 



28.5 



35.8 



Feb. 10 



29.3 



46.0 



13 



39.2 



40.5 



22 



33.4 



35.8 



Circle 



28° 0' 



21° 0' 



11 



35.8 



39.1 



14 



3Y.2 



43.2 



23 



34.1 



38.0 



11 



32.1 



34.6 



12 



30.1 



42.1 



15 



31.8 



46.2 



24 43.0 



29.9 



18 



33.8 



36.5 



13 



36.9 



89.3 



16 



39.0 



42.9 



Circle 25° 20', 28° 00' 



19 



33.1 



35.2 



14 



85.9 



39.1 



IT 



36.4 



44.1 



25 



18.0 



29.4 



20 



28.4 



34.6 



15 



31.8 



38.9 



18 



41.5 



42.0 



26 



26.1 



29.3 



21 



32.4 



35.2 



16 



31.9 



39.1 



22 



42.0 



42.4 



21 



2.5.1 



29.4 



22 



39.9 



35.5 



11 



34.2 



29.8 



23 



3T.2 



46.5 



28 



25.4 



29.1 



Circle 



23° 0' 



21° 0' 



18 



30.1 



31.4 



24 



43.1 



46.5 



29 



28.8 1 28.1 



23 



25.0 



36.1 



19 



35.8 



31.1 



25 



21.9 



36.5 



30 



28.4 



29.2 



24 



14.8 



31.5 



20 



36.3 



36.1 



Dec. 1 



43.3 



44.3 



31 



26.0 



28.1 



25 



11.3 



39.9 



21 



26.1 



85.1 



8 



25.9 



21.5 



1861 







26 



11.3 



39.0 



22 



33.8 



41.3 



4 



26.2 



21.1 



Jan. 2 



26.1 



34.2 



21 



28.0 



3.5.9 



23 



29.8 



88.9 



5 



24.1 



21.4 



3 



28.4 



30.8 



28 



31.6 



35.0 



24 



33.2 



39.2 



9 



33.2 



38.3 



4 



22.1 



30.3 



29 



33.2 



31.4 



25 



88.3 



38.1 



10 



25.6 



42.1 



5 



21.1 



30.6 



30 



34.1 



34.9 



26 



38.5 



38.1 



11 



34.6 



36.0 



6 



15.2 



29.0 



31 



33.6 



31.0 



21 



21.8 



38.9 



12 



35.5 



35.1 



1 



28.0 



30.8 



Feb. 1 



32.8 



29.5 



28 



26.6 



38.5 



13 



35.6 



35.1 



8 



. 28.5 



29.3 



2 



28.4 



36.0 



March 1 



30.0 



24.6 



14 



34.0 



35.6 



9 



28.1 



30.8 



3 



33.1 



35.4 



2 



35.5 



29.9 



15 



35.6 



24.4 



10 



29.0 



29.6 



4 



30.1 



36.0 



8 



36.9 



38.6 



16 



25.1 



35.8 



11 



21.1 



30.8 



5 



32.4 



35.0 



4 



85.1 



39.2 



n 



34.0 



34.3 



12 



26.3 



28.5 



6 



3.3.0 



35.3 



5 



38.3 



38.9 



18 



3.3.3 



36.9 



13 



28.6 



29.8 



1 



34.4 



35 6 



6 



31.6 



39.8 



19 



31.1 



38.8 



14 



24.1 



30.2 



8 



34.3 



34.1 



1 



36.1 



39.2 



20 



30.5 



36.2 



15 



28.6 



29.3 



9 



34.5 



34.9 



8 



38.5 



39.0 



