f a
"certain splendour" compassing round the hidden edge of the sun, as a
regular feature of total eclipses;[162] and the corona is expressly
mentioned in a description of an eclipse visible at Corfu in 968
A.D.[163] The first to take the phenomenon into scientific consideration
was Kepler. He showed, from the orbital positions at the time of the sun
and moon, that an eclipse observed by Clavius at Rome in 1567 could not
have been annular,[164] as the dazzling coronal radiance visible during
the obscuration had caused it to be believed. Although he himself never
witnessed a total eclipse of the sun, he carefully collected and
compared the remarks of those more fortunate, and concluded that the
ring of "flame-like splendour" seen on such occasions was caused by the
reflection of the solar rays from matter condensed in the neighbourhood
either of the sun or moon.[165] To the solar explanation he gave his own
decided preference; but, with one of those curious flashes of
half-prophetic insight characteristic of his genius, declared that "it
should be laid by ready for use, not brought into immediate
requisition."[166] So literally was his advice acted upon, that the
theory, which we now know to be (broadly speaking) the correct one, only
emerged from the repository of anticipated truths after 236 years of
almost complete retirement, and even then timorously and with
hesitation.

The first eclipse of which the attendant phenomena were observed with
tolerable exactness was that which was central in the South of France,
May 12, 1706. Cassini then put forward the view that the "crown of pale
light" seen round the lunar disc was caused by the illumination of the
zodiacal light;[167] but it failed to receive the attention which, as a
step in the right direction, it undoubtedly merited. Nine years later we
meet with Halley's comments on a similar event, the first which had
occurred in London since March 20, 1140. By nine in the morning of May
3, 1715, the obscuration, he tells us, "was about ten digits,[168] when
the face and colour of the sky began to change from perfect serene azure
blue to a more dusky livid colour, having an eye of purple intermixt....
A few seconds before the sun was all hid, there discovered itself round
the moon a luminous ring, about a digit or perhaps a tenth part of the
moon's diameter in breadth. It was of a pale whiteness, or rather pearl
colour, seeming to be a little tinged with the colours of the ir