David Rice Atchison (11 August 1807 - 26 January 1886) was a mid-19th century Democratic United States Senator from Missouri. He served as President Pro Tempore of the Senate for a total of six years. He is probably best known for the urban legend claiming that, for one day in March 1849, he was "de jure" President. Wikipedia
The daguerreotype of Atchison is taken from the archives of the Library of Congress . A large number of rare photographs can be found there. home.nycap.rr.com/useless/atchison/index.html
The definitive Wikipedia entry for David Rice Atchison. Wikipedia is the biggest multilingual free-content encyclopedia on the Internet. en.wikipedia.org/wiki/David_Rice_Atchison