528 FOOTE— FACTORS IN THE [April 25. 



The critical scrutiny to which theoretical prices are usually sub- 

 jected should not be discarded in considering the following trade 

 figures. They are not reproduced here as being true value indices in 

 all cases, and should therefore be analyzed before accepting them as 

 a guide in any important transfer. 



The total Wiilfing exchange values of 248 falls having both 

 Wiilfing and 1912 values, afford the factor 3.1904 -|-, when divided 

 into the total of the corresponding medium 1912 values in the present 

 collation. Hence the first column of figures is Wiilfing's theoretical 

 exchange index multiplied by the approximate factor 3.2.^ Wherever 

 Wiilfing gives two figures as of equal probability, the mean is em- 

 ployed. If he prefers one of two given, the preferred only is used. 

 Where he places both values within brackets as doubtful, both are 

 omitted. 



The second column of figures gives the 1899 medium market 

 prices. 



The third column gives the 1964 medium market prices. 



The fourth column gives the lowest 1912 market prices. 



The fifth and last column gives the medium 1912 market prices. 



The highest 191 2 price of any fall may be roughly calculated by 

 comparing its lowest with its average price for 1912. 



Prices arc per gram in dollars, counting M4 / = 4 / — ^^7.00. 



^ The approximate factor used by Cohen was 3.1 cents (13 pfgs.). 



