Jacob Reese Eckfeldt (March 1803-August 9, 1872) was an assayer for the United States Mint in Philadelphia.
He followed his father into the same area of government service, entering the U.S. Mint during an early period in his life.
Denied by English authorities as "impossible" because the London mint "makes no mistakes," Eckfeldt was vindicated by the resulting investigation which confirmed Eckfeldt's findings.
In response, parliamentary law ordered close examination of the weight and fineness of coins worldwide, which determined that coins produced in the United States were more uniform than the coins of other nations, a finding which enhanced Eckfeldt's worldwide reputation as an assayer.
Appointed to his post during Andrew Jackson's presidency, Eckfeldt held that position until his death.