: ( 59 ) 
only attain ihe perfection of which they are suscep- 
tible, in warm, dry, calcarious earth. 
10th. The ameliorating quality of tap-rooted nin 
is supposed to be in proportion to their natural dura- 
dion ; annual clover, (jupinella,) has less of this pro- 
perty than biennial, (Dutch clover,) biennial less 
than sainfoin, and sainfoin less than lucern. 
Lith. Any green crop ploughed into the soil, has an 
effect highly improving ; but for this purpose, lupins 
and buckwheat (cut when in flower) are most pro- 
per. | 
12th. Mixed crops, (as Indian corn, pumpkins, and 
peas and oats,) are much and profitably employed, 
and mith less injury to the soil than either corn or oats 
alone.(1) 
(1) The good effect of these mixtures was known to the ancients, from whom the 
practice has descended to us. What a picture of fertility and abundance have we in 
the 22d chap. 18th book of Pliny’s Natural History: ‘ Sub vite seritur frumentum, 
mox legumen, decinde olus, omnia, eodem anno, omniaque aliena umbra aluntur.”” 
—3+o~ 
SECTION V. 
Of Practical Agriculture and its necessa- 
ry Instruments. 
We begin this part of our subject with a few re- 
marks on the instruments necessary to agriculture, 
which may be comprised under the well known 
names of the plough, the harrow, the roller, the 
threshing machine and the fanning mill. 
Ist. Of the plough, 
