TERRESTRIAL MAGNETISZM. 



693 



These were compared with observations made at Sheerness. 

 Comparing the results obtained, we get — 





Dip. 



Observed 

 Force. 



Calculated. 





London 



Melville Island - 



70° 33-3' 

 88° 43-5' 



1 

 1-163 



1 

 1-153 



1 By dipping 

 1 needle. 







Dip. 



Observed 



Horizontal 



Force. 



Calculated 



Horizontal 



Force. 





Sheerness - 

 Melville Island - 



69° 55' 

 88° 43-5' 



13-33 



1 



13-275 



■ 1 



From several 



observations 



with three 



needles. 



Showing a remarkable agreement between theory and experi- 

 ment. 



A description is given of the special means employed to keep 

 the agate planes horizontal, and also of a better method of re- 

 leasing the magnet instead of employing another magnet for the 

 purpose. 



From observing the variation 128° 58' W., in longitude 91° 48' 

 W., and then 165° 50' 9" E. in longitude 103° 44' 37" (where the 

 dip was 88° 25 * 58'), Parry estimated that he was north of the 

 magnetic pole in longitude 100° W. 



and 



3. Appendix to Parry's Second Voyage in the " Fury 

 «' Hecla." 



(p. 97.) Observations were made to determine the Declination 

 on ice and on shore. On a floe 132 yards, and even at 200 yards 

 from the ship, the ship's influence on the needle was found to be 

 considerable, which is shown by the eff'ect of a change in the position 

 of the ship : the floes of ice to which it was attaclied had a slow 

 motion in azimuth. Observations were afterwards made at a 

 quarter of a mile from the ship. 



(p. 276.) Magnetic observations at Winter Island and at Igloolik 

 were generally made at 9 a.m. and 3 p.m. throughout the winter. 

 The mean of all the observations gave : 



Place. 



Lat. 



Long. 



Declina- 

 tion. 



Dip. 



Vnroa Time of 100 

 lorce. Vibrations. 



At Winter Is- 

 land - 



At Igloolik - 



o / 



66 11 

 69 21 



/ 



82 54 W. 

 81 37 W. 



o / 



57 24i 

 83 li 



o / // 



87 51 9 



88 9 49 



125 

 135 



4 57-3 

 4 46-7 



