623 
of Edinburgh, Session 1871-72. 
is the profit to the trader, one the interest to the capitalist, and 
one the wages of the labourer ; all these advantages are lost if the 
manufacture ceases. 
The gain of the labourer does not resemble the profit of the 
trader, or the interest of the capitalist. The profit of the trader is 
the difference between his valuation of the goods and what he 
gets for them. If he does not sell his goods he still has his 
goods, he only loses the profit. Similarly, if the capitalist does not 
sell his capital, he still has his capital. Now, the area P'PDIP 
represents the profit made by the capitalist on the particular 
employment of his capital, and this is all that he loses if unable to 
sell that capital ; but the area OP'D'D" represents the whole sum 
received by the labourers, not their profit. The profit of the 
labourer may perhaps be considered as the excess of wages which 
he earns in a particular trade, over that which would just tempt 
him to work rather than starve or go into the workhouse. 
If the consumer purchases the article for simple unproductive 
consumption, then the loss to him is only represented by the area 
DMN, If, however, a community purchases goods, and consumes 
them productively, then, by the cessation of the trade, they in their 
turn lose the interest on the capital they employ, and the labourers 
of the community lose their wages; so that, in that case, the loss 
to the buyer, who cannot be classed as an immediate consumer, is 
made up of three parts, similar to those enumerated in the case of 
the seller. 
Taxes on Trade . 
Having distinguished between the three distinct advantages 
given by trade, I will now consider the incidence of a tax on trade, 
levied as a fixed sum per unit of goods, as one pound per ton, or 
one shilling per gross. 
The effect of such a tax is to produce a constant difference 
between the price paid by the buyer and the price received by the 
seller. The market prices are determined in the diagram of the 
supply and demand curves, by the points between which a line 
parallel to OX, and equal in length to the tax, can be filled between 
the two curves. 
Thus, if in figure 3, FN be the demand curve, and PE the 
supply curve, and if the length of the line CC' be the amount of 
