e rays, including many
of the ultra-violet hydrogen series discovered by Sir William Huggins in
the emission of white stars.[542]

Dr. Schuster's photographs of the corona itself were the most extensive,
as well as the most detailed, of any yet secured. One rift imprinted
itself on the plates to a distance of nearly a diameter and a half from
the limb; and the transparency of the streamers was shown by the
delineation through them of the delicate tracery beyond. The singular
and picturesque feature was added of a bright comet, self-depicted in
all the exquisite grace of swift movement betrayed by the fine curve of
its tail, hurrying away from one of its rare visits to our sun, and
rendered momentarily visible by the withdrawal of the splendour in which
it had been, and was again quickly veiled.

From a careful study of these valuable records Sir William Huggins
derived the idea of a possible mode of photographing the corona _without
an eclipse_.[543] As already stated, its ordinary invisibility is
entirely due to the "glare" or reflected light diffused through our
atmosphere. But Huggins found, on examining Schuster's negatives, that a
large proportion of the light in the coronal spectrum, both continuous
and interrupted, is collected in the violet region between the
Fraunhofer lines G and H. There, then, he hoped that, all other rays
being excluded, it might prove strong enough to vanquish inimical glare,
and stamp on prepared plates, through _local_ superiority in
illuminative power, the forms of the appendage by which it is emitted.

His experiments were begun towards the end of May, 1882, and by
September 28 he had obtained a fair earnest of success. The exclusion of
all other qualities of light save that with which he desired to operate,
was accomplished by using chloride of silver as his sensitive material,
that substance being chemically inert to all other but those precise
rays in which the corona has the advantage.[544] Plates thus sensitised
received impressions which it was hardly possible to regard as spurious.
"Not only the general features," Captain Abney affirmed,[545] "are the
same, but details, such as rifts and streamers, have the same position
and form." It was found, moreover, that the corona photographed during
the total eclipse of May 6, 1883, was intermediate in shape between the
coronas photographed by Sir William Huggins before and after that event,
each picture taking its proper place in a se