MAGNETIC OBSERVATIONS. 417 



ing it in its meridian, which differed much indeed 

 from the other. When it had at last settled, I 

 drew it on one side 20° ; but the intervals often 

 vibrations were irregular, varying from 3' 50" to 

 3' 4f5" ; and though it stopped at its zero in five 

 minutes afterwards, I found the marked end had 

 moved easterly 6°, and so approached nearer 

 to Dollond's. Having waited some time longer, 

 during which it kept stationary, I made a fresh 

 set from that zero ; but the result was not more 

 satisfactory than the preceding ; and, finally, in- 

 stead of settling at its last, it returned to its first 

 zero. Had it not been for the variation in this 

 point, i. e. the arc between the two zeros, I 

 should have attributed, and probably with truth, 

 the apparent difference in the interval of vibra- 

 tions to the want of a fixed index or reading 

 glass for enabling me to determine the precise 

 moment of the turn of the needle : for so torpid 

 was it, that it seemed actually to stop dead at 

 the extremity of each arc, so as to render it a 

 matter of great nicety for the observer, even when 

 assisted by a good lens, to say when that instant 

 was. In order to decide between the two, a 

 set was next made with the lozenge needle, 

 which showed an entire difference from Han- 

 steen's of 22° in marking the north ; coinciding, 

 however, in this respect exactly with Dollond's. 

 The delicate pocket compass, graciously pre- 



K E 



