of Edinburgh, Session 1871 - 72 . 
629 
land which would be let, if the land paying no rent he fixed at 
each successive percentage. The actual quantity of land let will 
be determined by the intersection of the two curves, and is repre¬ 
sented by the height MD, fig. 4. 
If we now build a solid on the base OD'DN, such that its height 
all along each ordinate x is the number of hundreds of pounds of 
capital per acre required to give the percentage corresponding to 
the length x, then we shall have a volume standing on (OD'DN), 
the contents of which will measure the total annual returns from 
all the land cultivated.* The rent is the volume standing on 
MDN, the profit received by the farmers is the volume standing 
on OD'DM, and this is in excess of what would have just 
tempted them to cultivate by the volume MDP. We may, 
therefore, considering the farmer as a capitalist and a trader, call 
the volume on MDP his trade profit, and the volume on OD'D 
the interest on his capital. 
Y 
The effect of any tax on the land is to reduce the interest which 
each class of land is capable of returning on the capital employed. 
This it will do in very different ways according to the manner in 
which the tax is levied. 
* If L.150 per acre are required to give the percentage x of any one class of 
goods, the height of the ordinate perpendicular to the plane of OD'DN will 
be 1-5. 
4 p 
VOL. VII. 
