prising discovery of line-shiftings through end-on motion to the
study of prominences, the discontinuous light of which affords precisely
the same means of detecting movement without seeming change of place, as
do lines of absorption in a continuous spectrum. Indeed, his
observations at the sun's edge almost compelled recourse to an
explanation made available just when the need of it began to be felt. He
saw bright lines, not merely pushed aside from their normal places by a
barely perceptible amount, but bent, torn, broken, as if by the stress
of some tremendous violence. These remarkable appearances were quite
simply interpreted as the effects of movements varying in amount and
direction in the different parts of the extensive mass of incandescent
vapours falling within a single field of view. Very commonly they are of
a cyclonic character. The opposite distortions of the same coloured rays
betray the fury of "counter-gales" rushing along at the rate of 120
miles a second; while their undisturbed sections prove the persistence
of a "heart of peace" in the midst of that unimaginable fiery whirlwind.
Velocities up to 250 _miles a second_, or 15,000 times that of an
express train at the top of its speed, were thus observed by Young
during his trip to Mount Sherman, August 2, 1872; and these were
actually doubled in an extraordinary outburst observed by Father Jules
Fenyi, on June 17, 1891, at the Haynald Observatory in Hungary, as well
as by M. Trouvelot at Meudon.[642]

Motions ascertainable in this way near the limb are, of course,
horizontal as regards the sun's surface; the analogies they present
might, accordingly, be styled _meteorological_ rather than _volcanic_.
But vertical displacements on a scale no less stupendous can also be
shown to exist. Observations of the spectra of spots centrally situated
(where motions in the line of sight are vertical) disclose the progress
of violent uprushes and downrushes of ignited gases, for the most part
in the penumbral or outlying districts. They appear to be occasioned by
fitful and irregular disturbances, and have none of the systematic
quality which would be required for the elucidation of sun-spot
theories. Indeed, they almost certainly take place at a great height
above the actual openings in the photosphere.

As to vertical motions above the limb, on the other hand, we have direct
visual evidence of a truly amazing kind. The projected glowing matter
has, by the aid of