410 
MR. CHRISTIE ON THE MAGNETICAL OBSERVATIONS 
needle must have lost intensity during the expedition. The loss of intensity by the 
needles No. 1 and No. 3 appears to have been nearly the same, but that by the 
lozenge-needle is proportionally less than one half that by either of the others. With 
two of the needles. No. 1 and the Lozenge, it is not possible to determine whether 
this diminution of intensity took place previous to the arrival at Fort Reliance or 
subsequent to the final departure from that station ; but with the other, No. 3, it is 
clear that it lost intensity during the progress of the expedition from Fort Reliance 
to Point Ogle, and its return to the former station. The results do not indicate that 
any material change took place in the intensities of any of the needles during the 
residence at Fort Reliance. From the results with Nos. 1 and 3 it would appear 
that at Fort Reliance the horizontal intensity was rather greater in May than in the 
preceding October ; but those with the lozenge-needle indicate the reverse ; and this 
cannot be attributed to any loss of intensity in the needle itself, for the observations 
with that needle in the following October, on the return to Fort Reliance, give an in- 
tensity greater than any preceding. 
If, in deducing the intensity in the direction of the dip from the horizontal inten- 
sity, we take the mean of the results in London, and the mean of those at Fort Re- 
liance previous to quitting and on the return there, we shall have the following as 
standards for comparison : 
Mean measure of horizontal intensity. 
Needle No. 1. 
Needle No. 3. 
Lozenge-needle. 
At London. ..... 
At Fort Reliance . . 
•047984 
•0167486 
•0500646 
•0173400 
•283759 
•100032 
Assuming these and the measures of the horizontal intensity in the foregoing Table, 
corresponding to the respective stations, and dividing by the cosine of the dip, we 
obtain the results in the following Table for the measures of the intensity in the 
direction of the dip : 
— 
Needle No. 1. 
Needle No. 3. 
Lozenge- needle. 
Place of observation. 
Dip. 
Measure of 
intensity. 
Ratio of in- 
tensity to that 
at London. 
Measure of 
intensity. 
Ratio of in- 
tensity to that 
at London. 
Measure of 
intensity. 
Ratio of in- 
tensity to that 
at London. 
London 
O / 
69 43 
•138417 
1-00000 
•144429 
1-00000 
•818545 
1-00000 
Montreal 
Fort Reliance 
77 6 
84 1 
•160675 
1-160803 
•191714 
•166348 
1-32479 
1-15185 
•959637 
1-17237 
Musk-Ox Rapid. . . . 
Rock Rapid 
Point Beaufort .... 
Montreal Island .... 
Point Ogle 
85 54 
87 40 
88 3 
87 36 
89 24 
•178122 
•146653 
•086601 
•085249 
•185352 
1-23337 
1-01547 
0-59965 
0- 59029 
1- 28344 
•505126 
1-22769 
0- 61710 
1- 49984 
There is but little agreement between these results and those obtained from the 
