University of Vermont.
He moved to Milwaukee, Wisconsin in 1855. Cottrill practiced law in Milwaukee. He served as District of Milwaukee County from 1865 to 1866.
Cottrill died of tuberculosis on February 8, 1889.
He was buried at Forest Home Cemetery in Milwaukee.
He later served as a commissioner for the federal district courts in Wisconsin, and was a member of the committee appointed to organize and revise Wisconsin"s statutes in 1878. He was a member of the State Senate from 1883 to 1885.