may call the _texture_ of the sun's surface
derived new interest from a remarkable announcement made by Mr. James
Nasmyth in 1862.[503] He had made (as he supposed) the discovery that
the entire luminous stratum of the sun is composed of a multitude of
elongated shining objects on a darker background, shaped much like
willow-leaves, of vast size, crossing each other in all possible
directions, and possessed of unceasing relative motions. A lively
controversy ensued. In England and abroad the most powerful telescopes
were directed to a scrutiny encompassed with varied difficulties. Mr.
Dawes was especially emphatic in declaring that Nasmyth's
"willow-leaves" were nothing more than the "nodules" of Sir William
Herschel seen under a misleading aspect of uniformity; and there is
little doubt that he was right. It is, nevertheless, admitted that
something of the kind may be seen in the penumbrae and "bridges" of
spots, presenting an appearance compared by Dawes himself in 1852 to
that of a piece of coarse straw-thatching left untrimmed at the
edges.[504]

The term "granulated," suggested by Dawes in 1864,[505] best describes
the mottled aspect of the solar disc as shown by modern telescopes and
cameras. The grains, or rather the "floccules," with which it is thickly
strewn, have been resolved by Langley, under exceptionally favourable
conditions, into "granules" not above 100 miles in diameter; and from
these relatively minute elements, composing, jointly, about one-fifth of
the visible photosphere,[506] he estimates that three-quarters of the
entire light of the sun are derived.[507] Janssen agrees, so far as to
say that if the whole surface were as bright as its brightest parts, its
luminous emission would be ten to twenty times greater than it actually
is.[508]

The rapid changes in the forms of these solar cloud-summits are
beautifully shown in the marvellous photographs taken by Janssen at
Meudon, with exposures reduced at times to 1/100000 of a second! By
their means, also, the curious phenomenon known as the _reseau
photospherique_ has been made evident.[509] This consists in the
diffusion over the entire disc of fleeting blurred patches, separated by
a reticulation of sharply-outlined and regularly-arranged granules. The
imperfect definition in the smudged areas may be due to agitations in
the solar or terrestrial atmosphere, unless it be--as Dr. Schemer thinks
possible[510]--merely a photographic effect. M. Jansse