[2] In 1824 he was employed by surveyor and land speculator Orange Risdon to work with him on a detailed map of Michigan to be completed that year.
[2] Farmer found the delay and cost of sending his manuscripts east to be engraved in copper for printing time-consuming and expensive.
One of his most notable works was Map of the State of Michigan and the Surrounding Country, first issued in 1844 and revised eleven times before his death.
In 1826 Farmer married Roxanne Hamilton, also of Halfmoon, NY, and had three children, Silas, John, and Esther.
Upon Farmer's death on March 24, 1859,[5] Roxanne took over the business as produced several maps, then was succeeded by their oldest son Silas.