195 
Natural History . — Botany. 
dens, on each side of the central walk) had been much burnt 
up, or nearly deprived of their foliage. The ailanthus like- 
wise continues long in verdure : towards the end of September, 
it still retained its fine pinnated leaves, long after the walnut 
and the ash had shed theirs. 
33. Peat Mosses of Holland. — Without coals, and without 
copse-wood, the Dutch have to depend on their veener or peat- 
mosses for fuel. There are two kinds of these, the higher and 
the lower. The high mosses afford a layer of what is called 
grey or dry peat. This upper bed of peat is generally about 
six feet in thickness : it seems to be composed rather of leaves 
and stems of reedy plants, than of heath, or the plants which 
commonly accompany heath ; and fragments of large branches 
of trees have sometimes been found in it. Beneath this peat, a 
thin bed of blue clay commonly appears,' and which, on the peat 
being removed, forms arable land. The low mosses afford what 
are called mud-peats, and when these are taken from the infe- 
rior layer of such moss, the excavation speedily becomes cover- 
ed with water. When the under stratum of moss is firm and 
contains wood, it is called derry. Many trunks of trees occur 
in it ; and these uniformly lie with their heads pointing east- 
ward, showing that the storm or debacle which overwhelmed 
them had come from the west. Some of the timber, oak in par- 
ticular, remains sound, so that it can be used in carpentry ; but 
it is of a dark colour, as if stained with ink. There is a law 
against digging through this derry in the lowest parts of the 
country, much water being found to ooze in the sand below, 
and to be repressed by the compact layer of wood- moss. — Hort . 
Tour , pp. 187. and 237. 
34. Dutch Ashes are in great request by the industrious far- 
mers around Ghent, and in other parts of Flanders, proving to 
them a very useful manure. So far as we could learn, they are 
little used in Holland itself ; but they are carefully collected 
and sent by water to the Flemish agriculturists. As might be 
expected, Amsterdam produces by far the largest quantity. 
Messrs Sielring and Vander Aa, of that city, are the principal 
dealers. They have a lease of all the ashes of the capital, and 
likewise of those of the neighbouring towns. Tn Amsterdam 
n 2 
