414 
MR. CHRISTIE ON THE MAGNETICAL OBSERVATIONS 
in mind, were delicately suspended by fibres of silk, — and the uncertainty of their 
zero points, at Point Ogle, totally unconnected as these remarks are with the cause 
of this difficulty and uncertainty ; and I cannot omit to give them precisely as they 
are appended to the observations : “ This needle (No. 3) was extremely difficult to 
get into adjustment, and was so dull and heavy in its motion, that to have marked 
the precise time when it turned at each extremity would have required a fixed read- 
ing-glass. At the conclusion it settled within half a degree of its zero, but in five 
minutes after altered, without any apparent cause, 6°. I then made the following set 
(the second set of vibrations). This did not correspond with the former, neither 
did the needle settle at the same zero I began from, but returned to the first, and 
what I supposed to be the correct one.” With respect to the lozenge-needle, he re- 
marks : “There was a difference of no less than 22° between the north points of this 
and No. 3, though this agreed with Dollond’s light needle for adjusting the dip in- 
strument. As usual, it was more active, and, in this instance, far more regular (in 
its vibrations). Nevertheless another set was taken : the needle remained in perfect 
adjustment 
If we contrast the difficulty here manifest, in determining the direction of the mag- 
netic meridian by means of needles delicately suspended, with the facility with which 
its direction was, apparently, determined by Sir John Ross at Victory Harbour and 
Padliak, at which places he states that he ascertained the dip to be 89° 55' and 89° 56', 
we cannot but conclude that such results are greatly in excess. With such a dip, 
all determinate direction in a horizontal needle, arising from the force of terrestrial 
magnetism, however delicate might be the suspension of the needle, is quite out of 
the question ; and if a horizontal needle, so situated with respect to the pole of ver- 
ticity, had a determinate direction, it must have been due to the force exerted upon 
it by some mass in its vicinity. The dip at Victory Harbour, according to Captain 
James Ross’s observations -j-, is 88° 55', and at Padliak 89° 1 7 ' ; but even with this 
amount of dip I do not consider that the direction of the magnetic meridian could be 
ascertained, with anything like precision, by means of a Kater’s azimuth compass, 
however accurate might be its construction, and with whatever care it might be used. 
At Cape Isabella, where Captain James Ross observed the dip 89° 22', the north 
point of a Kater azimuth compass was directed to the north-west, but “ its action 
was uncertain to eight or ten degrees Captain Back remarked this sluggishness 
of the compass-needles from the time he quitted Rock Rapid; his own, — a small 
Rater’s azimuth very probably, certainly one of very delicate suspension, — he remarks, 
“frequently remained wherever it was placed, without evincing the slightest tendency 
to recover its polarity §.” I have referred to these circumstances of the two expe- 
ditions, because they all tend to show, quite independently of the agreement which I 
have noticed among the results deduced from the observations, that at Point Ogle, at 
* For further remarks on these observations, see Captain Back’s Narrative, p. 415. 
t Philosophical Transactions, 1834, p. 52. 1 Ibid., p. 49. § Narrative, p. 378. 
