This text is part of Parks’ Historical Signs Project and can be found posted within the park.Located at the intersection of Manhattan Avenue and Leonard Street in the Brooklyn neighborhood of Greenpoint, this large playground is named for Swedish-American inventor John Ericsson (1803-1869) and the nearby public junior high school that also bears his name. John Ericsson, a Swedish-born inventor and army officer, immigrated to America at the request of the United States Navy to supervise the construction of a ship that would utilize many of his revolutionary mechanical designs. Named the U.S.S. Princeton, Ericsson’s experimental frigate included state-of-the-art screw propellers, smokestacks, ventilators, optical instruments, and gun carriages. In 1861, the inventor was asked to research and design a new vessel for the Union Navy, the U.S.S. Monitor.