after the appearance
of the yellow aurora a sudden rise in atmospheric pressure, followed
by a gradual fall considerably below the normal pressure, was
recorded over the entire surface of the globe. Calculations based on
the time of arrival of this disturbance at widely separated points
show that it proceeded with the velocity of sound from a point
situated probably in Northern Labrador. The maximum rise of pressure
recorded was registered at Halifax, the self-recording barographs
showing that the pressure rose over six centimetres in less than
five minutes.

5. SHIFT IN DIRECTION OF THE EARTH'S AXIS. The axis of the
earth has been shifted in space by the disturbance and now points
almost exactly toward the double star Delta Ursae Minoris. This
change appears to have resulted from the circumstance that the force
was applied to the surface of the globe in a direction not quite
parallel to the direction of rotation, the result being the
development of a new axis and a shift in the positions of the poles,
which it will now be necessary to rediscover.

It appears that these most remarkable cosmic phenomena can be
explained in either of two ways: they may have resulted from an
explosive or volcanic discharge from the surface of the earth, or
from the oblique impact of a meteoric stream moving at a very high
velocity. It seems unlikely that sufficient energy to bring about
the observed changes could have been developed by a volcanic
disturbance of the ordinary type; but if radioactive forces are
allowed to come into play the amount of energy available is
practically unlimited.

It is difficult, however, to conceive of any way in which a sudden
liberation of atomic energy could have been brought about by any
terrestrial agency; so that the first theory, though able to account
for the facts, seems to be the less tenable of the two. The meteoric
theory offers no especial difficulty. The energy delivered by a
comparatively small mass of finely divided matter, moving at a
velocity of several hundred kilometres a second--and such a velocity
is by no means unknown--would be amply sufficient to alter the
velocity of rotation by the small amount observed.

Moreover, the impact of such a meteoric stream may have
developed a temperature sufficiently h