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instrument of great power, and may be seen at Lord Hawke's 
farm. The grass lands on the north side of the river Don 
are certainly of an inferior description, (some of the parks 
excepted,) few being sufficiently fertile to fatten cattle. 
There is some excellent grass land extending from near 
Carlton to the east side of Pontefract, the rent of which 
amounts to £3 per acre, while, in half-a-mile to the east, it 
again becomes inferior. It is extremely difficult to account, 
not only for the distribution of particular grasses upon the 
limestone, but for the unequal fertility which prevails in 
different places. At Stapleton, in the plantations under the 
fir tribe of trees, the superior grasses grow with the greatest 
luxuriance, but immediately upon passing into the open 
♦ country, there only exists the dwarf Cynosuros cristatus, 
Bromus pinnatus, B. sylvaticus, and one variety of Festuca, 
and not one hundred of these upon the square foot of turf. 
And in some of the parks, as Womersley, which is exceed- 
ingly well-manured, the grasses do not grow intermixed, but 
in separate clusters ; these are, Festuca pratensis, the Poa 
and Phleum pratense, Bromus mollis, and B. pinnatus, which 
is peculiar to the limestone, Alopecurus pratensis, but no 
Dactylus glomeratus, except under the fir trees. I can 
only think, that as the needles of the fir contain 6 per cent, 
of potass, and this salt is a constituent of all grasses, the 
increased growth is produced by their decomposition. While 
few weeds are found in the arable land, those in the pasture 
land are exceedingly numerous Dr. Lankester has given me 
a list of 300. It is said that the best grazing lands in the 
north, between Staindrop and Darlington, are upon this 
formation, and the production of grass around Tickhill cannot 
be due to any other cause than the intermixture of foreign 
debris, containing alumina ; it is hence very probable that 
some lands, particularly the thinner soils of Frystone, 
Stapleton, and Barnsdale, would be much benefited by the 
