
Caesium Atomic Clock, 1955.
1955
1955
1839 (original); circa 1988 (replica)
circa 1955
1955
1955
circa 1955
1955
1955
1955
1955
1955
1955
1955
1955
1955; 1830
2000-100 BCE
1955
1955
1955
1955
circa 1955
1990-96
circa 1955
1955
1830 (original); 1967 (model)
1955
1955
1955
1955
4000-2001 BCE
1903 (original); 1982 (model)
1955
1955
1955
1955
1955
1955
1955
1955-08-12
1956-09
1955-07-05
1955-06-16
1955-11-08
1955-11-14
1955-07-21
1962-10
1956-09
1955-07-20
1955-02-06
1964-10