Description: In celebration of our friends at the National Archives’ #ElectionCollection campaign, we are sharing some unique photos of U.S. Presidents in our collection.
Description: Henry David Hubbard (1870-1943), a physicist at the U.S. National Bureau of Standards, designed the first edition of the "Periodic Chart of the Atoms" in 1924. The chart is still in use today, continually updated to reflect new elements.