Lyndon Johnson actually said...
Now, Therefore, I, Lyndon B. Johnson,President of the United States of America, and presiding officer of the Smithsonian Institution, hereby proclaim the occasion of the bicentennial celebration of the birth of James Smithson; and I designate and set aside September 17 and 18, 1965, as special days to honor the memory of James Smithson and the accomplishments of the Institution that bears his name.
Context
Proclamation 3667—Smithson Bicentennial Celebration
08/12/1965