 In May 1778 , Morris convinced his captors to admit him to parole and was sent to Flatbush , Long Island , where he stayed with a Mr. Clarkson . In his memoir , Morris noted that Clarkson was " a man of science and large property , ... who owned the most extensive private library that [ Morris ] had ever known in the United States . " While still in captivity Morris found this situation rather comfortable and took every advantage of the library he so admired . 
