Polo has told us that in Eastern Yun-nan the exchange was 8 of silver for one of gold (ch. xlviii.); in the Western division of the province 6 of silver for one of gold (ch. xlix.); and now, still nearer the borders of Ava, only 5 of silver for one of gold.  Such discrepancies within 15 days’ journey would be inconceivable, but that in both the latter instances at least he appears to speak of the rates at which the gold was purchased from secluded, ignorant, and uncivilised tribes.  It is difficult to reconcile with other facts the reason which he assigns for the high value put on silver at Vochan, viz., that there was no silver-mine within five months’ journey.  In later days, at least, Martini speaks of many silver-mines in Yun-nan, and the “Great Silver Mine” (Bau-dwen gyi of the Burmese) or group of mines, which affords a chief supply to Burma in modern times, is not far from the territory of our Traveller’s Zardandan.  Garnier’s map shows several argentiferous sites in the Valley of the Lan-t’sang.

In another work[3] I have remarked at some length on the relative values of gold and silver about this time.  In Western Europe these seem to have been as 12 to 1, and I have shown grounds for believing that in India, and generally over civilised Asia, the ratio was 10 to 1.  In Pauthier’s extracts from the Yuen-shi or Annals of the Mongol Dynasty, there is an incidental but precise confirmation of this, of which I was not then aware.  This states (p. 321) that on the issue of the paper currency of 1287 the official instructions to the local treasuries were to issue notes of the nominal value of two strings, i.e. 2000 wen or cash, for every ounce of flowered silver, and 20,000 cash for every ounce of gold.  Ten to 1 must have continued to be the relation in China down to about the end of the 17th century if we may believe Lecomte; but when Milburne states the same value in the beginning of the 19th he must have fallen into some great error.  In 1781 Sonnerat tells us that formerly gold had been exported from China with a profit of 25 per cent., but at that time a profit of 18 to 20 per cent, was made by importing it.  At present[4] the relative values are about the same as in Europe, viz. 1 to 15-1/2 or 1 to 16; but in Canton, in 1844, they were 1 to 17; and Timkowski states that at Peking in 1821 the finest gold was valued at 18 to 1.  And as regards the precise territory of which this chapter speaks I find in Lieutenant Bower’s Commercial Report on Sladen’s Mission that the price of pure gold at Momein in 1868 was 13 times its weight in silver (p. 122); whilst M. Garnier mentions that the exchange at Ta-li in 1869 was 12 to 1 (I. 522).

Does not Shakspeare indicate at least a memory of 10 to 1 as the traditional relation of gold to silver when he makes the Prince of Morocco, balancing over Portia’s caskets, argue: 

  “Or shall I think in silver she’s immured,
  Being ten times undervalued to tried gold? 
  O sinful thought.”