Having considered theoretically the limitations and possible merits and defects of the money systems now in use, we shall next consider in how far the money under such systems conforms in practice to the chief requirement,--stability of value. Economic writers do not claim that either gold or silver is, or has been, of invariable value; but many of them do claim that gold is more nearly invariable than any other commodity, and that it is sufficiently so for money purposes, the changes in value being slight and covering long periods of time, so that from year to year they are almost imperceptible. Other writers claim that silver has been, of recent years at least, more stable in value than gold, and is therefore a better measure of value. The merits of these claims can be tested, in the same way that the stability of value of any commodity can be tested, by a comparison of the average purchasing power of each metal at different times. Prof. F. A. Walker, in the work already cited, observes, regarding money value under the gold standard as tested by average prices:-- "Not to speak of the enhancement, many fold, of the value of money through the Silver Famine of the Middle Ages, or of the sudden and extensive decline which has been referred to as taking place between 1570 and 1640, it is estimated by Professor Jevons that the value of gold fell 46 per cent. between 1789 and 1809, that from 1809 to 1849 it rose 145 per cent., while between 1849 and 1874 it fell again at least 20 per cent." Coming down to more recent times, we have more full and accurate data, and there have been several careful compilations and averages of prices made in different countries. The report of the Finance Committee of the United States Senate, 52d Congress, on "Wholesale Prices, Wages, and Transportation," known as the "Aldrich Report," is doubtless the most accurate and complete examination of prices in this country from 1840 to 1892 that has ever been made. This report also gives for comparison the tables of Soetbeer and Sauerbeck (two of the most distinguished European statisticians), and the table of the _Economist_ (London) as to foreign prices, all reduced to the same basis, and to United States money units in gold. In order to facilitate comparison of these data, the tables have been platted as diagrams in Plate 1. All the tables were prepared by taking the prices of a selected list of commodities for the year 1860 as 100, and calculating the variations in the price of each commodity from the price of that year as a percentage of rise or fall. The average of these percentages for each year represents, therefore, average prices for that year, as compared with 1860, and it is these averages which are platted in the diagrams. The list of commodities selected by the Senate Committee embraces 223 articles for the years subsequent to 1860. Prior to that time the number was less, varying from 85 to 223, according as data were to be had.