an artistic fact, how graciously these structures adapt
themselves to such diverse scenes,--equally, though variously,
picturesque amid the sturdy foliage and wild gorges of the Alps, the
bustle, fog, and mast-forest of the Thames, and the crystal atmosphere,
Byzantine edifices, and silent canals of Venice.

Whoever has truly felt the aerial perspective of Turner has attained a
delicate sense of the pictorial significance of the bridge; for, as we
look through his floating mists, we descry, amid Nature's most
evanescent phenomena, the span, the arch, the connecting lines or masses
whereby this familiar image seems to identify itself not less with
Nature than with Art. Among the drawings which Arctic voyagers have
brought home, many a bridge of ice, enormous and symmetrical, seems to
tempt adventurous feet and to reflect a like form of fleecy cloud-land;
daguerreotyped by the frost in miniature, the same structures may be
traced on the window-pane; printed on the fossil and the strata of rock,
in the veins of bark and the lips of shells, or floating in sunbeams, an
identical design appears; and, on a summer morning, as the eye carefully
roams over a lawn, how often do the most perfect little
suspension-bridges hang from spear to spear of herbage, their filmy span
embossed with glittering dew-drops!

* * * * *

INTERNAL STRUCTURE AND PROGRESSION OF THE GLACIER.

It is not my intention, in these articles, to discuss a general theory
of the glaciers upon physical and mechanical principles. My special
studies, always limited to Natural History, have but indifferently
fitted me for such a task, and quite recently the subject has been
admirably treated from this point of view by Dr. Tyndall, in his
charming volume entitled "Glaciers of the Alps." I have worked upon the
glaciers as an amateur, devoting my summer vacations, with friends
desirous of sharing my leisure, to excursions in the Alps, for the sake
of relaxation from the closer application of my professional studies,
and have considered them especially in their connection with geological
phenomena, with a view of obtaining, by means of a thorough acquaintance
with glaciers as they exist now, some insight into the glacial phenomena
of past times, the distribution of drift, the transportation of
boulders, etc. It was, however, impossible to treat one series of facts
without some reference to the other; but such explanations as I have
g