is, and
to be concentric with the moon, whence I concluded it the moon's
atmosphere. But the great height thereof, far exceeding our earth's
atmosphere, and the observation of some, who found the breadth of the
ring to increase on the west side of the moon as emersion approached,
together with the contrary sentiments of those whose judgment I shall
always revere" (Newton is most probably referred to), "makes me less
confident, especially in a matter whereto I confess I gave not all the
attention requisite." He concludes by declining to decide whether the
"enlightened atmosphere," which the appearance "in all respects
resembled," "belonged to sun or moon."[169]

A French Academician, who happened to be in London at the time, was less
guarded in expressing an opinion. The Chevalier de Louville declared
emphatically for the lunar atmospheric theory of the corona,[170] and
his authority carried great weight. It was, however, much discredited by
an observation made by Maraldi in 1724, to the effect that the luminous
ring, instead of travelling _with_ the moon, was traversed _by_ it.[171]
This was in reality decisive, though, as usual, belief lagged far behind
demonstration. In 1715 a novel explanation had been offered by Delisle
and Lahire,[172] supported by experiments regarded at the time as
perfectly satisfactory. The aureola round the eclipsed sun, they argued,
is simply a result of the _diffraction_, or apparent bending of the
sunbeams that graze the surface of the lunar globe--an effect of the
same kind as the coloured fringes of shadows. And this view prevailed
amongst men of science until (and even after) Brewster showed, with
clear and simple decisiveness, that such an effect could by no
possibility be appreciable at our distance from the moon.[173] Don Jose
Joaquim de Ferrer, however, who observed a total eclipse of the sun at
Kinderhook, in the State of New York, on June 16, 1806, ignoring this
refined optical _rationale_, considered two alternative explanations of
the phenomenon as alone possible. The bright ring round the moon must be
due to the illumination either of a lunar or of a solar atmosphere. If
the former, he calculated that it should have a height fifty times that
of the earth's gaseous envelope. "Such an atmosphere," he rightly
concluded, "cannot belong to the moon, but must without any doubt belong
to the sun."[174] But he stood alone in this unhesitating assertion.

The importance of the problem w