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OBSERVATIONS ON THE MAGNETIC DIP. 379 
Table B affords the following exhibit of the dip by the observations made at the Stan- 
stead station, in Canada Kast: 
a vee : | ~~ Mean 
Needle No. 1. | Needle No, 2, | of both needles. 
By sixty-four observations made in the plane of the mag- | 
netic merigge | .  i ce Le oe 76° 08.48 | 
By ninety-six observations made in the plane of the mag- : | 76° 08'.64 
netic meridian, .; . 3. | 76° 08.80 
By three hundred and twenty observations made at every, 
15° of azimuth, between 0° and 90°, and between 270°, 
and 360° of the azimuth circle, and reduced to the | 
plane of the magnetic meridian, 
76" 09',35176 07'.53' 76° 08.'44 
Here we have a closer coincidence even, than before, between the dip observed by the 
two needles in the plane of the magnetic meridian, and that deduced from the azimuthal 
observations. 
What is also particularly satisfactory in this series is, that the greatest difference be- 
tween any one of the reduced dips found in column ten and the dip derived from one 
hundred and sixty observations on the two needles, in the plane of the magnetic meri- 
dian, is, for needle No. 1, only 1/.48, and for needle No. 2, only 1’.47. 
The greatest difference, in column nine, between the inclination observed in any azi- 
muth at this station, and that computed for the same azimuth, is, for needle No.-1, only 
3’.09, and this is for an azimuth so great as 75° from the magnetic meridian. The next 
greatest difference for this needle is only 1’.5. 
The greatest difference, in that column, for needle No. 2, is only 2’.16, being for azi- 
muth 60°, the next greatest is 2.07, and the third in order is 1/.94. 
The tests afforded by the two series of observations presented in tables A and B, of the 
qualities of the instruments, both as to the accuracy of form of the axles of the two 
needles, and the freedom of the metal of which the instrument is composed from magnet- 
ism and from all matter of a nature to attract or repel the needles from the true angles 
of inclination, seem exceedingly satisfactory, and must be considered as entitling the 
extensive series of observations that have been made with it to every confidence. It will 
be remembered, too, that these tests have been thus rigidly applied after the instrument 
has been in use nearly five years, and they show that it has not been deteriorated in its 
qualities by the many and very extensive journeys that have been performed with it 
amidst many very trying difficulties, resulting from the peculiarities of the country it 
has traversed. 
We must not omit to acknowledge the credit due to that distinguished artist, Mr. 
Gambey of Paris, for the production of so perfect an instrument for measuring the mag- 
netic dip. 
LV. Canaan Corner, Vermont and Canada Boundary. 
Latitude 45° 00’ 49”, N.; Longitude 4h. 46m. 04s., west. Observations for the dip 
made in the plane of the magnetic meridian, by Major Graham. 
VOL. IX.—-99 
