And Improvement of) Soils. 197 
one conclude, that it will fit a foot of larger or less size 
or different form, but I must confess that passing over 
things equally obvious, I have run into numerous and 
expensive errors. 
But when it is enquired upon what evidence it is to 
be received—the reply is at hand,living evidences, are 
at the command of every one who chooses to make the 
trial, let him however, be on his guard, against suffer- 
ing himself to take a crop in place of the spring pasture 
oats. 
If it shall still be enquired, how does the oat pasture 
fertilize? It may be also observed that the constant ver- 
dure and green herbage prevent the rays of the sun 
from parching the soil and depriving of its moisture and 
air, both of which are highly necessary to vegetation. 
The double portion of juicy vegetable matter arising 
from the two crops of pasture in the same summer, be- 
ing every where united with the common soil partly 
mechanically and partly chemically, renders the soil 
capable of retaining sufficient moisture and elastic air, 
to make it open and warm, and by which the soil does 
not only become thicker by going downward, but ac- 
tually expands, or rises, so as to give a furrow, con- 
siderably, deeper, than formerly, over immoveable 
rocks. Some years ago, a field in view of the farm- 
house, marked the broad rocks, during the course of 
every crop; they are now covered with so much soil, 
that they are seldom observed. The two ploughings 
also contribute to the increase of the air in the soil, 
without which no soil can be fruitful, there being no 
vegetation in vacuo. Tull’s horse hoeing husbandry, 
was introduced under the idea, that the pabulum of 
