ther of
Turner's important mountain designs; for the reader must feel the
disadvantage they are under in being either reduced in scale, or divided
into fragments: and therefore these chapters are always to be considered
merely as memoranda for reference before the pictures which the reader
may have it in his power to examine. But this one drawing of the St.
Gothard, as it has already elucidated for us Turner's knowledge of crest
structure, will be found no less wonderful in the fulness with which it
illustrates his perception of the lower aqueous and other curvatures. If
the reader will look back to the etching of the entire subject, Plate
+21+, he will now discern, I believe, without the necessity of my
lettering them for him, the lines of fall, rounded down from the crests
until they plunge into the overhanging precipices; the lines of
projection, where the fallen stones extend the long concave sweep from
the couloir, pushing the torrent against the bank on the other side; in
the opening of the ravine he will perceive the oblique and parallel
inclination of its sides, following the cleavage of the beds in the
diagonal line A B of the reference figure; and, finally, in the great
slope and precipice on the right of it, he will recognize one of the
grandest types of the peculiar mountain mass which Turner always chose
by preference to illustrate, the "slope above wall" of _d_ in Fig. 13,
p. 148; compare also the last chapter, Sec.Sec. 26, 27. It will be seen, by
reference to my sketch of the spot, Plate +20+, that this conformation
does actually exist there with great definiteness: Turner has only
enlarged and thrown it into more numerous alternations of light and
shade. As these could not be shown in the etching, I have given, in the
frontispiece, this passage nearly of its real size: the exquisite greys
and blues by which Turner has rounded and thrown it back are necessarily
lost in the plate; but the grandeur of his simple cliff and soft curves
of sloping bank above is in some degree rendered.

We must yet dwell for a moment on the detail of the rocks on the left in
Plate +37+, as they approach nearer the eye, turning at the same time
from the light. It cost me trouble to etch this passage, and yet half
its refinements are still missed; for Turner has put his whole strength
into it, and wrought out the curving of the gneiss beds with a subtlety
which could not be at all approached in the time I had to spare for this
p