 Grinnell subsequently wrote Lincoln with introductions for others, becoming something of a conduit of political power, if not a wielder of such himself.Grinnell was Collector of the Port of New York from March 1869 to July 1870, and the Port's Naval Officer of Customs from July 1870 to April 1871.Perhaps best remembered for his work as Central Park Commissioner during the early years of the urban park's design and construction.