17 5 
imprudent use of the hatchet by the early culti- 
vators of the country in which they exist : when 
the trees are felled in the outskirts of a wood, those 
in the interior exposed to the influence of the 
winds, and having been accustomed to shelter, 
become unhealthy, and die in their new situation ; 
and their leaves and branches gradually decompos- 
ing, produce a stratum of vegetable matter. In 
many of the great bogs in Ireland and Scotland, 
the larger trees that are found in the out-skirts of 
them bear the marks of having been felled. In 
the interior few entire trees are found 5 and the 
cause is, probably, that they fell by gradual decay ; 
and that the fermentation and decomposition of 
the vegetable matter was most rapid where it was 
in the greatest quantity. 
Lakes and pools of water are sometimes Ailed 
up by the accumulation of the remains of aquatic 
plants ; and in this case a sort of spurious peat is 
formed. The fermentation in these cases, however, 
seems to be of a different kind. Much more gaseous 
matter is evolved ; and the neighbourhood of mo- 
rasses in which aquatic vegetables decompose is 
usually aguish and unhealthy ; whilst that of the 
true peat, or peat formed on soils originally dry, 
is always salubrious. 
The earthly matter of peats is uniformly analo- 
gous to that of the stratum on which they repose ; 
the plants which have formed them must have de- 
rived the earths that they contained from this 
stratum. Thus in Wiltshire and Berkshire, where 
the stratum below the peat is chalk, calcareous 
earth abounds in the ashes, and very little alumina 
