144 Disturbance of the Earth’s Magnetism. 
2. When the beams of the aurora shoot up so as to pass the zenith, 
which is sometimes the case, the point of their convergence is in the 
direction of the prolongation of the dipping needle at the place of 
observation. 3. It has also been observed, that during the appear- 
ance of an active and brilliant aurora, the magnetic needle often 
becomes restless, varies sometimes several degrees, and does not 
resume its former position until after several hours. 
From the above facts, it has been generally inferred that the auro- 
ra is In some way connected with the magnetism of the earth; and 
that the simultaneous appearance of the meteor, and the disturbance 
of the needle, are either related as cause and effect, or as the com- 
mon result of some more general and unknown cause. 
The subject is, however, involved in much obscurity ; and there 
are some facts which tend to throw doubt on the connexion of the 
two phenomena. The. accurate and valuable observations of Col. 
Beaufoy in England, continued for several years, add nothing to- 
wards establishing the fact of the magnetic influence of the aurora ; 
and in the scientific expeditions under Capt. Parry, to the north, 
in the peculiar regions, as it would appear, of this meteor, no un- 
usual disturbance of the needle was observed to accompany the 
aurora, although the apparatus was visited every hour in the day, 
and sometimes oftener, when any thing rendered it desirable. In- 
deed, so far from producing a disturbing effect, Dr. Brewster con- 
cludes, from a comparison of the observations, that the aurora, in 
the arctic regions, seems rather to exercise a sedative influence.* 
On the other hand, Dr. Richardson states, from his own observa- 
tions, made at Bear Lake, during six successive months of the 
years, 1825-6, and again in 1826-7, that the aurora does influence 
the magnetic needle. ‘A careful review of the daily register,” 
says he, “has led me to form the following conclusion: That bril- 
liant and active coruscations cause a deflection of the needle almost 
invariably, if they appear through a foggy atmosphere, and if pris- 
matic colors are exhibited ; on the contrary, when the atmosphere is 
clear, and the aurora presents a dense steady light of a yellow color, 
and without motion, the needle is often unaffected.”+ 
In this state of knowledge, every additional fact becomes of some 
importance. The following communication, it is therefore hoped, 
* Edinburgh Philosophical Journal of Science, vol. 8. 
+ Edinburgh New Philosophical Journal, vol. 5. 
