190 Professor Whewell on the 



Let p be the price at which cloth can be imported into Chili 

 from England, with English profits. Then it is here supposed 

 that p is the price at which it is there sold, though it may for 

 a time be sold for a higher price from the demand being active, 

 or for a lower price, the supply being excessive. The gradual 

 extension of demand, and the fluctuations and miscalculations of 

 supply, though causes of perpetual and powerful operation, are 

 left out of consideration, as not effecting that condition of equi- 

 librium to which our investigations here refer. The estimation of 

 these alternations, indeed, appears to be a fitter employment for the 

 sagacity of the practical merchant, than for the reasoning of the 

 theoretical economist. To apply mathematical formulae to them 

 would probably not be a more successful undertaking than it 

 would be to calculate on mechanical principles, the alternation 

 of smaller and larger surges in the progress of a rising tide. 



15. I shall now proceed to determine mathematically the con- 

 ditions and consequences of an export and import trade- 

 Let p be the price of a unit of a commodity manufactured 

 here and carried into a foreign country, />' the price at which 

 it could be manufactured in the foreign country: then if p<p' 

 the article will be exported. Let e be the quantity exported, 

 then ep is the value exported of such a commodity : and Sep, 

 the sum of all such products, is the whole exported value. 



Similarly, if * be the value of a commodity imported, *' the 

 price at which it could be manufactured here, it will be im- 

 ported if s<s\ And i being the quantity, Sis is the whole im- 

 ported value. 



If Sep is not = Sis, the balance Sep- Sis must be imported 

 in gold, which will thus be added to the quantity of gold 



