e certain that the corona is not
noticeably enlarged by atmospheric causes. A sky drifted over with thin
cirrus clouds and air changed with aqueous vapour amply accounted for
the abnormal amount of scattering in 1870.

But even in 1870 positive evidence was obtained of the substantial
reality of the radiated outer corona, in the appearance on the
photographic plates exposed by Willard in Spain and by Brothers in
Sicily of identical dark rifts. The truth is, that far from being
developed by misty air, it is peculiarly liable to be effaced by it. The
purer the sky, the more extensive, brilliant, and intricate in the
details of its structure the corona appears. Take as an example General
Myer's description of the eclipse of 1869, as seen from the summit of
White Top Mountain, Virginia, at an elevation above the sea of 5,523
feet, in an atmosphere of peculiar clearness.

"To the unaided eye," he wrote,[557] "the eclipse presented, during the
total obscuration, a vision magnificent beyond description. As a centre
stood the full and intensely black disc of the moon, surrounded by the
aureola of a soft bright light, through which shot out, as if from the
circumference of the moon, straight, massive, silvery rays, seeming
distinct and separate from each other, to a distance of two or three
diameters of the solar disc; the whole spectacle showing as on a
background of diffused rose-coloured light."

On the same day, at Des Moines, Newcomb could perceive, through somewhat
hazy air, no long rays, and the four-pointed outline of the corona
reached at its farthest only a _single semidiameter_ of the moon from
the limb. The plain fact, that our atmosphere acts rather as a veil to
hide the coronal radiance than as the medium through which it is
visually formed, emerges from further innumerable records.

No observations of importance were made during the eclipse of September
9, 1885. The path of total obscurity touched land only on the shores of
New Zealand, and two minutes was the outside limit of available time.
Hence local observers had the phenomenon to themselves; nor were they
even favoured by the weather in their efforts to make the most of it.
One striking appearance was, however, disclosed. It was that of two
"white" prominences of unusual brilliancy, shining like a pair of
electric lamps hung one at each end of a solar diameter, right above the
places of two large spots.[558] This coincidence of diametrically
opposite dis