les. The
whole ring-system, too, appears to be somewhat elliptical.[1103]

The satellite-theory has derived unlooked-for support from photometric
inquiries. Professor Seeliger pointed out in 1888[1104] that the
unvarying brilliancy of the outer rings under all angles of
illumination, from 0 deg. to 30 deg., can be explained from no other
point of view. Nor does the constitution of the obscure inner ring
offer any difficulty. For it is doubtless formed of similar small
bodies to those aggregated in the lucid members of the system, only much
more thinly strewn, and reflecting, consequently, much less light. It is
not, indeed, at first easy to see why these sparser flights should show
as a dense dark shading on the body of Saturn. Yet this is invariably the
case. The objection has been urged by Professor Hastings of Baltimore.
The brightest parts of these appendages, he remarked,[1105] are more
lustrous than the globe they encircle; but if the inner ring consists of
identical materials, possessing presumably an equal reflective capacity,
the mere fact of their scanty distribution would not cause them to show
as dark against the same globe. Professor Seeliger, however,
replied[1106] that the darkening is due to the never-ending swarms of
their separate shadows transiting the planet's disc. Sunlight is not,
indeed, wholly excluded. Many rays come and go between the open ranks of
the meteorites. For the dusky ring is transparent. The planet it
encloses shows through it, as if veiled with a strip of crape. A
beautiful illustration of its quality in this respect was derived by
Professor Barnard from an eclipse of Japetus, November 1, 1889.[1107]
The eighth moon remained steadily visible during its passage through the
shadow of the inner ring, but with a progressive loss of lustre in
approaching its bright neighbour. There was no breach of continuity. The
satellite met no gap, corresponding to that between the dusky ring and
the body of Saturn, through which it could shine with undiminished
light, but was slowly lost sight of as it plunged into deeper and deeper
gloom. The important facts were thus established, that the brilliant and
obscure rings merge into each other, and that the latter thins out
towards the Saturnian globe.

The meteoric constitution of these appendages was beautifully
demonstrated in 1895 by Professor Keeler,[1108] then director of the
Alleghany Observatory, Pittsburgh. From spectrographs taken with the
s