1030 A.D. the records of both of which possibly imply that the
Corona was noticed, we may find ourselves on thoroughly firm ground in
considering the eclipse of April 9, 1567. Clavius, a well-known writer
on chronology, undoubtedly saw then the Corona in the modern acceptation
of the word but thought it merely the uncovered rim of the Sun. In reply
to this Kepler showed by some computations of his own, based on the
relative apparent sizes of the Sun and Moon, that Clavius's theory was
untenable. Kepler, however, put forth a theory of his own which was no
better, namely, that the Corona was due to the existence of an
atmosphere round the Moon and proved its existence. From this time
forwards we have statements, by various observers, applying to various
eclipses, of the Corona seeming to be endued with a rotatory motion. The
Spanish observer, Don A. Ulloa, in 1778, wrote thus respecting the
Corona seen in that year:--"After the immersion we began to observe round
the Moon a very brilliant circle of light which seemed to have a rapid
circular motion something similar to that of a rocket turning about its
centre." Modern observations furnish no counterpart of these ideas of
motion in the Corona. Passing over many intervening eclipses we must
note that of 1836 (which gave us "Baily's Beads") as the first which set
men thinking that total eclipses of the Sun exhibited subsidiary
phenomena deserving of careful and patient attention. Such attention
was given on the occasion of the eclipses of 1842 and 1851, still
however without the Corona attracting that interest which it has gained
for itself more recently. It was noticed indeed that the Corona always
first showed itself on the side of the Moon farthest from the vanishing
crescent but the full significance of this fact was not at first
realised. Mrs. Todd well remarks:--"In the early observations of the
Corona it was regarded as a halo merely and so drawn. Its real structure
was neither known, depicted, nor investigated. The earliest pictures all
show this. Preconceived ideas prejudiced the observers, and their
sketches were mostly structureless.... It should not be forgotten that
the Coronal rays project outward into space from a spherical Sun and do
not lie in a plane as they appear to the eye in photographs and
drawings." After remarking on the value of photographs of the Corona up
to a certain point because of their automatic accuracy Mrs. Todd very
sensibly says, "but pen