
Obsidian possibly used in trephination experiments
1918-1920
1918-1920
1919
1920-1925
1917
1918
1925-1926
1830 (original); 1967 (model)
1924
1918
2000-100 BCE
1921
1934
1926
1918
1918
1916-1917
1920
1922
1955; 1830
1925
1920
1920-1925
1917
1924
1925
1923
1921
1923
1917-1918
1925
1924
circa 1920
1916
1921-1926
1920
circa 1920
1922-1923
1922-1923
1922-1923
1922-1923
circa 1916
1926
1926
circa 1920
1920
1801-1892 (prepared); 1946 (element replaced)
4000-2001 BCE
1934
1839 (original); circa 1988 (replica)
1926