
Obsidian possibly used in trephination experiments
1918-1920
1918-1920
1918
1920-1925
1952-3
1830 (original); 1967 (model)
circa 1919
1919
1923
1923
1917
1926
1920
1668; 1924
1610; 1923
circa 1923
circa 1925
1926
1920
1924
1918
1922
1916
1921
1924
1926
1925
1920-1925
1917
1918
1925
1922-1923
1922-1923
1921
1922-1923
1922-1923
1921-1926
1925
1923
circa 1920
1955; 1830
1918
1916-1917
1924
1926
1921
2000-100 BCE
1917-1918
1923
circa 1920
1920