ng
the turf. Six and a half years subsequently this field was
re-examined, and the fragments were now found at from 4 to 5 inches
beneath the surface. So that in this interval of 61/2 years, about
11/2 inch of mould had been added to the superficial layer. I am surprised
that a greater quantity had not been brought up during the whole
211/2 years, for in the closely underlying black, peaty soil there were many
worms. It is, however, probable that formerly, whilst the land
remained poor, worms were scanty; and the mould would then have
accumulated slowly. The average annual increase of thickness for the
whole period is .19 of an inch.

[Illustration: FIG. 1.
Section of the vegetable mould in a field, drained and reclaimed
fifteen years previously; a, turf; b, vegetable mould without
any stones; c, mould with fragments of burnt marl, coal cinders,
and pebbles; d, sub-soil of black, peaty sand with quartz
pebbles.]

Two other cases are worth recording. In the spring of 1835 a field,
which had long existed as poor pasture, and was so swampy that it
trembled slightly when stamped on, was thickly covered with red sand
so that the whole surface appeared at first bright red. When holes
were dug in this field after an interval of about 21/2 years, the sand
formed a layer at a depth of 3/4 inch beneath the surface. In 1842
(i.e., seven years after the sand had been laid on) fresh holes were
dug, and now the red sand formed a distinct layer, 2 inches beneath
the surface, or 11/2 inch beneath the turf; so that on an average
.21 inches of mould had been annually brought to the surface. Immediately
beneath the layer of red sand the original sub-stratum of black, sandy
peat extended.

A grass field, likewise not far from Maer Hall, had formerly been
thickly covered with marl, and was then left for several years as
pasture; it was afterwards ploughed. A friend had three trenches dug
in this field 28 years after the application of the marl, and a layer
of the marl fragments could be traced at a depth, carefully
measured, of 12 inches in some parts, and of 14 inches in other parts.
This difference in depth depended on the layer being horizontal,
whilst the surface consisted of ridges and furrows from the field
having been ploughed. The tenant assured me that it had never been
turned up to a greater depth than from 6 to 8 inches; and as the
fragments formed an unbroken horizontal layer from 12 to 14 inches
beneath th