in the theory of value and prices. 



43 



11. 



5. The marginal utility of each commodity to each individual 

 — represented by the ordinate of each cistern, i. e. by the distance 

 from its top to the water level. 



6. The money price of each commodity — represented (in any 

 cistern in the same front-and-back-row) by the thickness of the back 

 compartment, and registered on scales^ p^, Pb-> Pc at the rear. (The 

 relation of price to marginal utility will recur.) 



v. The prices of commodities in terms of each other — represented 

 by the ratios of their ordinates. 



8. The marginal utility of money to each individual — repre- 

 sented (in any cistern in the same right-and-left-row) by the ratiof 

 of the ordinate of that cistern to the 

 thickness of its back compartment 

 and registered on scales^ U I, U II, 

 U III at the right. 



The units of these magnitudes 

 are : 



1. The unit of commodity is a 

 ton, yard, gallon, etc., and is repre- 

 sented by (say) a cubic inch of 

 water. 



2. The unit of money is (say) a 

 dollar and is represented by (say) a 

 cubic inch of water. 



3. The unit of price is one dollar 

 per ton, yard, gallon, etc., and is 

 represented by one inch. 



4. The unit^ of marginal utility 

 for each individual is the marginal 

 utility of (say) 100 tons of A. It 

 may be called a util and by a proper 



whence 



* The rods EER are each connected by a cord and pulley with the pointers of 

 the scales p^, p^, p^, 



f This ratio is evidently the marginal utility of money ("valuation of money ") 



because as seen in chapter IV, S 3, — -. = -— . w 



dU 



cZU _ dK __ ordinate of cistern 



dm p^ thickness of its back compartment' 



X Fig. 11 (which views the outside of the right wall of the tank) shows the 



device by which this is accomplished. Evidently from the labels 



dU 



X dA dJJ 



- = or a; = — 



J p d)}i 



The pointer obviously varies with x. It is so arranged as to register zero when 

 cc = 0. 



