Charles A. Sherrill, Tenn. State Library & Archives; has furnished the following information on this subject according to his understanding of the material he has read at the TNGenWEb Project.
"The groom had to assure the State that he was able to be legally married (was not already married to someone else, under age, or ineligible because of close blood relationship, etc.)
This assurance was given in the form of a bond for a certain amount of money. The friend or relative signed as the groom's security on the bond, commonly known as becoming a bondsman.
If indeed the groom had been sued for violating the marriage contract, the bondsman would have had to pay any legal damages if the groom defaulted.
No money actually changed hands at the time the bond was issued. This bonding procedure was used across Tennessee and in other southern states in the 19th century.
It's a good thing no money actually changed hands--I doubt that James or John (Polly's brother) could have come up with $1250.
Mary "Polly" Gresham Corbett died in 1884 at age 96. Two of her brothers married two of James' sisters, Martha and Polly. As near as I can tell from the records handed down, James Corbett and his siblings were 2nd generation Americans, and their father, an Irish immigrant, fought in the Revolutionary War, and received a pension. Although in the 19th century they all lived in Tennessee, originally they lived in North Carolina, the western part of which became eastern Tennessee.