They are masses of glowing gas, which have been flung
from great depths beneath the visible surface of the
sun. May we not conclude that the smaller prominences
which constitute the sierra are of like nature ? that they
also have been flung from beneath tha sun's visible sur-
face ? As respects the larger prominences we can have
no manner of doubt, because they have been seen to be
flung out in eruptive sort. And this refers to all orders
of prominences, except only those very numerous and
relatively very small prominences which crowd together
so as to form the seemingly continuous coloured sierra.
These cannot be watched as the others have been. But
it seems highly probable that those among them which
are not the remains of Loftier prominences are, like
their larger fellows, phenomena of eruption.
Again, as respects the corona, all the evidence we
have is opposed to the conception that the phenomenon
is atmospheric. It shows two regions, which, though
not separated by well-defined limits from each other,
may yet be regarded as, in a sense, distinct. There ia



I



TB£ SUITS TMUB ATMOSPHERE



91



an inner and brighter portion, wliich the sesquipedalians
have proposed to call the leitcosphere, — apparently on
the liiciis a non luceiidu principle, for it is neither
whits nor spherical. And there is the outer portion,
much less brilliant, and much more strikingly radiated.
