1. Sketch showing extension of primary triangulation : along the 39th parallel to the Capes of Delaware. June 30, 1897 Yale Public content 1897. 2013-11-08T17:39:40Z. 2013-11-21T21:36:24Z. U.S. Coast and Geodetic Survey, issuing body. U.S. Coast and Geodetic Survey. English. Public. Middle Atlantic States and Georgia.