for ascertaining the Deviation of the Magnetic Needle. 369 



rous eddies and ripplings. By keeping on the South, or con- 

 tinental shore, and passing along by Cape N.E. within two 

 or three hundred yards of the rocks, we succeeded, with the 

 assistance of the boats a-head, in getting through the channel 

 soon after eleven o'clock." 



Extract from Captain Lyon's Voyage of Discovery, 

 Latitude 61° 13'— Longitude 63° 54'. 

 " The deviation of our compasses was here very great and 

 irregular, although less so with our head Northward, than 

 otherwise : even Gilbert's excellent azimuth compass required 

 constant tapping, although under the influence of Professor 

 Barlow's plate, which had hitherto corrected it with the great- 

 est accuracy." — Page 30. 



« The stillness of this day was highly favourable for obtain- 

 ing observations for the dip of the needle ; but the floe to 

 which we were fast was not of sufficient extent to admit of our 

 getting so far from the ship as to be free from her attraction : 

 I was now the more desirous of obtaining these observations, 

 on account of the fast increasing sluggishness of the com- 

 passes,— for that of Gilbert's, which had hitherto been fully 

 corrected for the local attraction of the ship by Barlow's plate, 

 now beoan to show nearly as much deviation when our head was 

 to the Eastward, as any of the other compasses."— Page 44.. 

 " Our compasses had now become quite useless, with our 

 head Southerly ; and that in particular to which the plate was 

 fitted, so powerless, that its North point stood wherever it was 

 placed by the finger ; but with our head Northerly, they all 

 traversed again. This, however, benefited us but litde ; for, 

 as our route lay to the South-west, we were without other 

 guidance than celestial bearings, which could not always be 

 obtained." — Page 53. • , • i 



" In the forenoon watch, our larboard compass, which, with 

 two others, had shown our head N. b. W. which (with three 

 points and a half westerly variation) agreed with the sun's 

 bearing, in giving a N. W. ^ W. course, suddenly pointed 

 E.N.K, and no tapping or motion would keep it in any other 

 point for two or three minutes ; after which, it as suddenly re- 

 covered its agreement with the others, and continued quite 

 correct. We now, from repeated observations, discovered 

 that when our head was nearly North by compass, the devia- 

 tion was three points and a half West ; but when between 

 North and West, it amounted to eight pomts ; while with the 

 head to the Southward, the compasses would generally rest 

 whesever they were directed by the finger ; and sometimes 

 cacli persisted in maintaining a dircclion of ils own. 



Vol. 65. No. 325. Maj/ 1825. 3 A ''Barlow'.^ 



