This primary source comes from the Records of the Hydrographic Office.
Full Citation: North Pacific Ocean; 1849; Manuscript Hydrographic Charts, 1866–1908; Records of the Hydrographic Office, Record Group 37; National Archives at College Park, College Park, MD. [Online Version, https://www.docsteach.org/documents/document/north-pacific-ocean-1849, April 23, 2024]