interest; and much was done by men with exceptionally keen eyesight,
like Mr. Dawes. But it was a difficult subject, owing to the rapidity
of the changes in appearance of the so-called rice-grains, about 1" in
diameter. The rapid transformations and circulations of these
rice-grains, if thoroughly studied, might lead to a much better
knowledge of solar physics. This seemed almost hopeless, as it was
found impossible to identify any "rice-grain" in the turmoil after a
few minutes. But M. Hansky, of Pulkowa (whose recent death is
deplored), introduced successfully a scheme of photography, which
might almost be called a solar cinematograph. He took photographs of
the sun at intervals of fifteen or thirty seconds, and then enlarged
selected portions of these two hundred times, giving a picture
corresponding to a solar disc of six metres diameter. In these
enlarged pictures he was able to trace the movements, and changes of
shape and brightness, of individual rice-grains. Some granules become
larger or smaller. Some seem to rise out of a mist, as it were, and to
become clearer. Others grow feebler. Some are split in two. Some are
rotated through a right angle in a minute or less, although each of
the grains may be the size of Great Britain. Generally they move
together in groups of very various velocities, up to forty kilometres
a second. These movements seem to have definite relation to any
sun-spots in the neighbourhood. From the results already obtained it
seems certain that, if this method of observation be continued, it
cannot fail to supply facts of the greatest importance.

It is quite impossible to do justice here to the work of all those who
are engaged on astronomical physics. The utmost that can be attempted
is to give a fair idea of the directions of human thought and
endeavour. During the last half-century America has made splendid
progress, and an entirely new process of studying the photosphere has