which were covered with coarse grass and had apparently existed in this
state from time immemorial, I found (Oct. 22, 1872) after several wet
days that almost all the many castings were considerably elongated in the
line of the slope; and that they now consisted of smooth, only slightly
conical masses. Whenever the mouths of the burrows could be found from
which the earth had been ejected, there was more earth below than above
them. After some heavy storms of rain (Jan. 25, 1872) two rather steeply
inclined fields near Down, which had formerly been ploughed and were now
rather sparsely clothed with poor grass, were visited, and many castings
extended down the slopes for a length of 5 inches, which was twice or
thrice the usual diameter of the castings thrown up on the level parts of
these same fields. On some fine grassy slopes in Holwood Park, inclined
at angles between 8 and 11 30 with the horizon, where the surface
apparently had never been disturbed by the hand of man, castings abounded
in extraordinary numbers: and a space 16 inches in length transversely to
the slope and 6 inches in the line of the slope, was completely coated,
between the blades of grass, with a uniform sheet of confluent and
subsided castings. Here also in many places the castings had flowed down
the slope, and now formed smooth narrow patches of earth, 6, 7, and 71 2
inches in length. Some of these consisted of two castings, one above the
other, which had become so completely confluent that they could hardly be
distinguished. On my lawn, clothed with very fine grass, most of the
castings are black, but some are yellowish from earth having been brought
up from a greater depth than usual, and the flowing-down of these yellow
castings after heavy rain, could be clearly seen where the slope was 5 ;
and where it was less than 1 some evidence of their flowing down could
still be detected. On another occasion, after rain which was never
heavy, but which lasted for 18 hours, all the castings on this same
gently inclined lawn had lost their vermiform structure; and they had
flowed, so that fully two-thirds of the ejected earth lay below the
mouths of the burrows.
These observations led me to make others with more care. Eight castings
were found on my lawn, where the grass-blades are fine and close
together, and three others on a field with coarse grass. The
inclination of the surface at the eleven places where these castings
were collected varied between 4 30 and 17 30 ; the mean of the
eleven inclinations being 9 26 . The length of the castings in the
direction of the slope was first measured with as much accuracy as
their irregularities would permit. It was found possible to make these
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