Image from Wikimedia Commons
Sandra Wassilie - CC BY-SA 3.0
unknown -
Contemporary photograph - Public Domain
X-PRIZE - CC BY 2.0
Public Domain
Sir_George_Hayter - Public Domain
Philkon - CC BY-SA 3.0
Charles Willson Peale (1741-1827) - Public Domain
Norman Abramson - Public Domain
Davebabsmith - CC BY-SA 4.0
Robert C. Clark Photo - CC BY-SA 4.0
William Morris Agency-management. Photographer-Maurice Seymour, New York. - Public Domain
U.S. Navy - Public Domain
Western Press Bureau Company (Denver, CO), publisher. - Public Domain
Image from Wikimedia Commons
Carlson, John Roy, 1909-
Image from Wikimedia Commons
Wordsworth, Christopher, 1807-1885
Image from Wikimedia Commons
Sandra Wassilie - CC BY-SA 3.0
Satin, Mark Ivor, 1946-
Image from Wikimedia Commons
Salisbury, Robert Cecil, marquess of, 1830-1903
Image from Wikimedia Commons
unknown -
Koffka, Kurt, 1886-1941
Image from Wikimedia Commons
Osborne, Henry Zenas, 1848-1923
Image from Wikimedia Commons
Contemporary photograph - Public Domain
Ritschl, Albrecht, 1822-1889
Image from Wikimedia Commons
Leopold I, Holy Roman Emperor, 1640-1705
Image from Wikimedia Commons
Hardy, Jack, 1947-2011
Image from Wikimedia Commons
Harrold, Thomas L. (Thomas Leonard), 1902-1973
Image from Wikimedia Commons
Cash, William
Image from Wikimedia Commons
X-PRIZE - CC BY 2.0
Brooks, Avery
Image from Wikimedia Commons
Public Domain
Goodin, John Randolph, 1836-1885
Image from Wikimedia Commons
United States. Works Progress Administration
Image from Wikimedia Commons
Sir_George_Hayter - Public Domain
Mudford, William, 1782-1848
Image from Wikimedia Commons
Lucier, Alvin
Image from Wikimedia Commons
Philkon - CC BY-SA 3.0
Yarrow, Peter, 1938-....
Image from Wikimedia Commons
Becquerel, Ed., 1820-1891
Image from Wikimedia Commons
Hesiod
Image from Wikimedia Commons
Charles Willson Peale (1741-1827) - Public Domain
Sevier, John, 1745-1815
Image from Wikimedia Commons
Norman Abramson - Public Domain
Abramson, Norman.
Image from Wikimedia Commons
Davebabsmith - CC BY-SA 4.0
Smith, James, 1782-1867
Image from Wikimedia Commons
Norton, Caroline Sheridan, 1808-1877
Image from Wikimedia Commons
Robert C. Clark Photo - CC BY-SA 4.0
Poland, Thomas M., 1949-
Image from Wikimedia Commons
William Morris Agency-management. Photographer-Maurice Seymour, New York. - Public Domain
Sherwood, Roberta
Image from Wikimedia Commons
Taylor, Robert, 1911-1969
Image from Wikimedia Commons
U.S. Navy - Public Domain
Chandler, Alfred W., 1890-1978
Image from Wikimedia Commons
Walton, Ernest, 1903-1995
Image from Wikimedia Commons
Western Press Bureau Company (Denver, CO), publisher. - Public Domain
Symes, G. G. (George Gifford), 1840-1893
Image from Wikimedia Commons
Shorthouse, J. H. (Joseph Henry), 1834-1903