Science Advisor to the President War II by President Franklin Delano Roosevelt. Vannevar Bush chaired this office through Roosevelt's death in 1945, and continued under Roosevelt's successor Harry S. Truman until 1951. After the war, President Harry S. Truman replaced the OSRD with the Science Advisory Committee in 1951. The office was moved to the White House on November 21, 1957, by President Dwight D. Eisenhower to provide advice and recommendation in response to the Space Race started by the USSR's launch of the first artificial Earth satellite, Sputnik 1. President Richard M. Nixon eliminated the PSAC in 1973, rather than appointing a replacement for
President pro tempore of the United States Senate Between 1792 and 1886, the president pro tempore was second in the line of presidential succession following the vice president and preceding the speaker. Through 1891, the president pro tempore was appointed on an intermittent basis only, when the vice president was not present to preside over the Senate, or at the adjournment of a session of Congress. Langdon served four separate terms from 1789 to 1793. During the 4th Congress (1795 – 1797); in all, more than a 12 senators held the office during the Senate’s first decade. When called upon to serve, they would preside, sign legislation, and