E 
SUPPLY AND DEMAND 
65 
Were it to receive continuously less than 7d. 
a yard for its output the pay of some at least 
of its agents would have to be reduced to an 
inadequate level, and they would conse 
quently be disposed to seek some other 
occupation, and even if they did not the gaps 
in their ranks created by time would wait in 
vain to be filled up. Hence, we may conclude 
at once that the supply price for a given out 
put must tend in the long run to equal at least 
the highest of the costs involved in the attain 
ment of that output. And it cannot for long 
be more. Were the demand price for 100,000 
yards of braid per year more than 7d., and 
were the price, under the influence of the 
competition of the buyers, forced up to the 
demand price, as it would be, productive agents 
would be attracted to the industry because in 
such circumstances producers and capital 
in the industry would be receiving more than 
normal remuneration. So we may suppose 
that another firm would be added to the 
four already in existence. Premise that the 
cost of production of the fifth firm is 7|d. 
If this were the highest cost under the new 
conditions, the new firm, which we shall call 
E, would be the marginal firm under the new 
conditions and the supply price would reach 
7£d. for an output of five firms. Let us take