e corona; but they differed from each other in magnitude....
The whole of these three protuberances were visible even to the last
moment of total obscuration; at least, I never lost sight of them when
looking in that direction; and when the first ray of light was admitted
from the sun, they vanished, with the corona, altogether, and daylight
was instantaneously restored."[154]

Notwithstanding unfavourable weather, the "red flames" were perceived
with little less clearness and no less amazement from the Superga than
at Pavia, and were even discerned by Mr. Airy with the naked eye. "Their
form" (the Astronomer Royal wrote) "was nearly that of saw-teeth in the
position proper for a circular saw turned round in the same direction in
which the hands of a watch turn.... Their colour was a full lake-red,
and their brilliancy greater than that of any other part of the
ring."[155]

The height of these extraordinary objects was estimated by Arago at two
minutes of arc, representing, at the sun's distance, an actual elevation
of 54,000 miles. When carefully watched, the rose-flush of their
illumination was perceived to fade through violet to white as the light
returned, the same changes in a reversed order having accompanied their
first appearance. Their forms, however, during about three minutes of
visibility, showed no change, although of so apparently unstable a
character as to suggest to Arago "mountains on the point of crumbling
into ruins" through topheaviness.[156]

The corona, both as to figure and extent, presented very different
appearances at different stations. This was no doubt due to varieties in
atmospheric conditions. At the Superga, for instance, all details of
structure seem to have been effaced by the murky air, only a
comparatively feeble ring of light being seen to encircle the moon.
Elsewhere, a brilliant radiated formation was conspicuous, spreading at
four opposite points into four vast luminous expansions, compared to
feather-plumes or _aigrettes_.[157] Arago at Perpignan noticed
considerable irregularities in the divergent rays. Some appeared curved
and twisted, a few lay _across_ the others, in a direction almost
tangential to the moon's limb, the general effect being described as
that of a "hank of thread in disorder."[158] At Lipeszk, where the sun
stood much higher above the horizon than in Italy or France, the corona
showed with surprising splendour. Its apparent extent was judged by
Struve to be