Historical Ratios of Gold to Silver
Silver has had a monetary function far longer than gold, being used as the most common medium of exchange in everyday commerce since well before the time of Christ. In fact, silver again lasted longer than gold as a medium of exchange. No doubt if people were free to circulate whatever kind of money they chose, silver would again become the common man's first choice.

The first metal used as a currency was silver, before 2000 BC, when silver ingots were used in trade, and it was not until 1500 years later that the first coinage of pure gold was introduced.
Historically, silver was valued at approximately 1/12 the price of gold or what I call the natural ratio. Once silver and gold were both used as money, silver was 1/16th the price of gold. This is what I refer to as the "classic" ratio or monetary ratio. This 1/16 ratio held from 1700 to 1860, one hundred and sixty years. Only in recent history has the gold/silver ratio risen above the "classic" 16:1. If we use the classic ratio, then one troy ounce of silver would be over $25 with gold at $450.

If you had a chart 45 feet long where every foot represented one century of history, the ratio of gold to silver (for most of human history, a band from 8:1 to 12:1 ) would never rise above 16 to one until the last fifteen inches. According to AGI "Abundance of Elements," silver occurs at 0.07 ppm and gold at 0.004 ppm in the earth's crust with a naturally occurring ratio is 17.5:1. Interesting - that's not far from the last monetary ratio 16:1 set when both gold and silver were still universal money in the last century

Historical Ratios of the Price of Gold to the Price of Silver
Menes (1st Egyptian Dynasty, 3100 BC) gold/silver price ratio of 1 to 2½
Croesus Mermnadae (561-546 BC) official gold/silver price ratio of 1 to 13 1/3
Augustus (Early Imperial Rome) gold/silver price ratio of 1 to 12.50
Charlemagne (AD 781) gold/silver price ratio of 1 to 12.00
Edward III (14th Century England gold/silver price ratio of 1 to 11.57
Jean le Bon (14th Century France) gold/silver price ratio of 1 to 11.11
Spain 1500 massive silver supplies from the Western Hemisphere jump above ratio 1 to 13.0
China 1400 to 1600 gold/silver price ratio of 1 to 5 rising to 1 to 8
Spain 1687 gold/silver price ratio of 1 to 15.0
Isaac Newton (Royal Mint, 1717) gold/silver price ratio of 1 to 15.21
Napoléon Bonaparte (1803) gold/silver price ratio of 1 to 15.5
France's bimetallic system 1848 to1873 French legal ratio of 1 to 15.5
US Coinage Act of 1873 gold/silver price ratio of 1 to 16.00
US 1876 gold/silver price ratio of 1 to 18
US 1886 gold/silver price ratio of 1 to 20
US 1900 gold/silver price ratio of 1 to 33
US 1910 gold/silver price ratio of 1 to 38
1930s Roosevelt forced China off the silver standard. Removing all that monetary demand for silver made it lose value against gold, industrial demand could not soak up the excess supply
US 1941 for the first time in history, the ratio hit 1 to 100.
US 1980 gold/silver price ratio of 1 to 16.00
Late 2003 gold/silver price ratio of 1 to  75
Mid 2004 gold/silver price ratio of 1 to 50 to 1 to 70
January 2006 gold/silver price ratio is about 1 to 60
June 2007 gold/silver price ratio is about 1 to 49