"Frederick W. King was born in London, England in 1821.  He came to America in 1830 and died in Baltimore, Maryland in 1889.  Richard King was born in London in 1823 and died in Baltimore in 1905.  The New York City Directory of 1849-50 lists F. W. & R. King mathematical instrument makers at 13 Nassau.  The Baltimore, Maryland Directories from 1851 to 1852 list F. W. & R. King mathematical and nautical instrument makers as successors to James Green.  They are listed through 1875."

Reference:  Smart, Charles E.   The Makers Of Surveying Instruments In America Since 1700  Troy, New York:  Regal Art Press.  1962