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16 NATURE OF CAPITAL AND INCOME [Cuar. I 
measurement includes, as we have seen, two elements: 
a unit of measure, which may be inaceurate; and a number 
or ratio between the quantity to be measured and the unit, 
which number may also be inaccurate. In modern times 
the first source of error is practically eliminated. Our 
units of weight and measure are standardized by law, and 
a pound weight in California is equal to one in Connecticut, 
within one part in many thousand. The chief source of 
error, therefore, lies not in the unit, but in the ratio of the 
wealth to that unit. In retail trade the inaccuracy is as 
great as five per cent, or greater. Wholesale transactions 
are more accurate. A large manufacturing concern of 
Syracuse had its measurement of the weight of caustic 
soda sold in carload lots compared with the measurement 
made by its customers, and the results agreed within one 
fifth of one per cent on two fifty-carload lots. Probably 
the greatest degree of accuracy ever obtained in com- 
mercial measurements is on the Mint scales used by the 
United States in Philadelphia and San Francisco. These 
scales weigh accurately to within about one part in ten 
million. 
When we proceed from quantities of wealth to values, 
we introduce still a third source of inaccuracy, namely, in 
the price factor by which we multiply. This is especially 
true if the price be merely an “appraised” price. The price 
of any actual sale is an absolute fact and cannot be said to 
Lave any inaccuracy; but the price at which we estimate 
that a thing would sell under certain conditions is always 
uncertain. In the case of staple articles, 1.e. articles regu- 
larly on the market, a dealer can often appraise correctly 
within one per cent. Real estate in certain parts of a city 
where sales are active can sometimes be appraised correctly 
within five or ten per cent; but in the “dead” or out-of- 
the-way parts of some towns, where sales are infrequent, the 
appraisement becomes merely a rough guess. Again, in 
the country districts, while farms in the settled parts of 
  
  
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