A couple of reasearch questions for you

[stev32k]

U.S. silver dollars weigh around 27 grams (26.9 - 27.2). The forerunner of the U.S. silver dollar the pillar dollar weighs 27 grams. Going even further back the forerunner of the pillar dollar the Potosi 8 reales cob was supposed to weigh 27 grams. Does anyone know how or why 27 grams was chosen as a standard weight?

 

Another question. I see the term "COB" used to describe some older coins like the Potosi 8 reales and some gold coins. The one thing they seem to have in common is that they were made by hand, but I've never been able to find the definition of "COB. Anyone know what it is?

[ldhair]

Cut out of a bar.

[BillJones]

COB = Coba de barros - the end of the bar.

 

These crude coins were made from close to circular bars of the silver and gold that were called "Spanish fingers." The planchets were cut from the end of the bar like a loaf of bread.

 

As to your weight question, I'll venture this answer. The early U.S. dollars were intended to trade at par with the Spanish milled dollars. I suppose that 27 grams represented the value in silver for 8 reales, which was the basic Spanish dollar unit. David Ganz wrote in his book about the history of the U.S. mint that Alexander Hamilton took a sample of the coins then in circulation in America to come up the weights that he proposed for the first U.S. coinage.