outspread wings. The southern observers watched it go right into the
sun, when it instantly disappeared. What had happened was that the
comet in passing its perihelion point had swung exactly between the
earth and the sun. On the following morning it was seen from all parts
of the world close by the sun on the opposite side, and it remained
thus visible for three days, gradually receding from the solar disk.
It then became visible for northern observers in the morning sky
before sunrise, brandishing a portentous sword-shaped tail which, if
it had been in the evening sky, would have excited the wonder of
hundreds of millions, but situated where it was, comparatively few
ever saw it.

The application of photography to the study of comets has revealed
many curious details which might otherwise have escaped detection, or
at best have remained subject to doubt. It has in particular shown not
only the precise form of the tails, but the remarkable vicissitudes
that they undergo. Professor Barnard's photographs of Brooks' comet in
1893 suggested, by the extraordinary changes in the form of the tail
which they revealed, that the comet was encountering a series of
obstructions in space which bent and twisted its tail into fantastic
shapes. The reader will observe the strange form into which the tail
was thrown on the night of October 21st. A cloud of meteors through
which the comet was passing might have produced such deformations of
its tail. In the photograph of Daniels' comet of 1907, a curious
striping of the tail will be noticed. The short bright streaks seen in
the photograph, it may be explained, are the images of stars which are
drawn out into lines in consequence of the fact that the photographic
telescope was adjusted to follow the motion of the comet while the
stars remained at rest.