o 
Feb. 2, 1882] 
seems as if the aurora were cast out of its exterior edge, 
but in reality there is nothing but a common stratus- 
cloud, or a low-lying frost-mist, which extends upon a 
certain part of the horizon, and which has no other con- 
nection with the aurora than to diminish its brillancy, 
whereby the apparent horizon is a little elevated above 
the true one. The dark segment seemed in this case to 
be yet darker, and the light seemed to be cast out of the 
edge of the cloud. “I can maintain with full certitude,” 
Baron Nordenskjéld says, ‘‘that the lighted segment of 
clouds which we saw during the winter of 1875-79 had 
this origin ; and most probably, several luminous mists 
which we saw during the nights of March 18 and 20, close 
by our ship, close by the ice, were due to the same cause ; 
but I cannot affirm that quite certainly.” 
The observations and measurements which were made 
at the Vega winter-quarters have led Nordenskjold to the 
following conclusions as to the nature of aurorz :— 
“Our globe,” he says, “ even during a minimum aurora 
year, is adorned with an almost constant crown of light, 
single, double, or multiple, whose inner edge was usually, 
Fic. 2.—Map showing the position of the aurora-glory. 
during the winter of 1878-79, at a height of about 003 
radius of the earth above its surface, whose surface was 
somewhat wzder the earth’s surface, a little north of the 
magnetic pole, and which, with a diameter of about 0°32 
radius of the earth, extends in a plane perpendicular to 
the earth’s radius which passes through the centre of this 
luminous ring.” An idea of this double luminous crown, 
which Nordenskjéld has named the “aurora-glory,” will 
be conveyed by the drawing, Fig. 2. 
Of these two luminous rings of the aurora-glory, the 
interior, or the “‘common arc,” is the most regular, and 
it is almost permanent. But it is visible only in such 
parts of the Arctic regions as are mostly not inhabited by 
people of European origin; and this circumstance, to- 
gether with its feeble brilliancy, was the cause of its not 
having attracted till now the attention it deserves. It is 
known that even in Sweden the aurore begin sometimes 
with the appearance of a halo-like arc, not divided into 
rays, and which must not be confounded with the ray- 
auroree which also often take the shape of a luminous 
arc. But this regular arc which sometimes is seen in 
Si MATORE 
49 
321 
winter-quarters : it is a second outer ring situated in the 
same plane as the interior one, but does not have the 
same regularity nor permanency. As to the ray-aurore, 
visible in more southern regions, they are but a particular 
form of the aurora considered as a whole ; they are but 
emissions of rays from the crowns of light, or aurora 
glories, which surround the Polar regions of our globe. 
The true position of the permanent inner circle of the 
aurora glory could be easily determined if we had simul- 
taneous measurements made at two distant points. But 
such observations not being made, Nordenskjéld tries 
to determine it from measurements made at Kolutchin 
Bay, admitting the following most probable supposi- 
tions:—That the glory is situated in a plane perpen- 
dicular to the earth’s radius, which passes through its 
centre; that it is circular, and that its centre is situated 
somewhere in the neighbourhood of the magnetic pole. 
Admitting these suppositions, and with the measurements 
made during the wintering of the Vega, Nordenskjold 
arrives, by means of calculations, at the conclusion that 
the centre of the aurora glory does not coincide with the 
magnetic pole, but is situated about 81° N. latitude, and 
80° E. longitude, and, to avoid mistakes, he proposes to 
give to this pole the name of the “Auroral Pole.” The 
summit of the common aurora arc being visible in the 
direction of the magnetic North when seen from places 
situated beyond the projection of the glory on the earth’s 
surface, and in the magnetic South for observers situated 
within this projection, it is most probable that the centre 
| of the glory is within the ellipse which circumscribes that 
| surface of the earth about this same place. 
Sweden is not that which was observed at the Vega's | 
| part of the Arctic regions where the inclination is 90°. 
But a glance on a map representing the magnetic 
meridians shows that this hypothesis is far better satis- 
fied when admitting that the aurora-pole is situated 
at the above-mentioned place, than if we admit that it 
coincides with the magnetic pole. The sections of the 
great circles tangential to the magnetic meridians at a 
distance of 20° to 30 from the magnetic pole, meet the 
But it should 
be remembered that the section of the Juminous crown, 
| as also the position of its centre undergo certain changes. 
Under ordinary citcumstance these changes are slow and 
within certain narrow limits; but during aurora-storms 
they are both rapid and wide. In these cases luminous 
arcs having different centres may appear at once. It is 
| probable that it would not be difficult to determine, from 
observations made at two distant places, the laws of these 
changes ; but with the measurements we have now at our 
disposal it is impossible. ‘ We can,’ Nordenskjold says, 
“only point out the main features of the phenomenon, 
| and the above-mentioned figures are intended only to 
facilitate the understanding of the conception of auror 
which I try to establish.’’ Beak 
(To be continued.) 
THEODOR SCHWANN 
7T~HE death is announced of the distinguished physio- 
logist whose name will be for ever associated with 
the history of the ‘cell-theory.’ He was born at Neuss 
near Dusseldorf in 1810, and was therefore in his seventy- 
second year. The most important fact in the history of 
his mental development, is that he came under the 
influence of the greatest teacher and worker in biological 
science whom Germany rich in such men, has ever 
| produced, namely Johannes Muller. Schwann was by nine 
years the junior of his great master, who died whilst in 
the full tide of active work, at the comparatively early age 
of fifty-seven. When Schwann was twenty-three years 
of age, having completed his medical studies, he became 
Joh. Miiller’s assistant in the Anatomical Museum of 
Berlin and: remained there for five years. In 1839 he 
was called to the chair of Anatomy in the Catholic 
University-of Louvain, being then in his twenty-eighth 
