
Obsidian possibly used in trephination experiments
1918-1920
1918-1920
1919
1839 (original); circa 1988 (replica)
1952-3
1917
c.1912
1907
1907
1913
1910
1917
1910
1915
1906-1915
1906
1934
2000-100 BCE
1914-1918
1920
1910-1920
1955; 1830
1910
1908
1909
1912
1910
1918
1915
1912
1913
1914-1918
1906
1910
1914
1906
1907-1917
1907-1917
1907-1917
1915
1910-1920
1920
1907
1914-1918
1914-1918
1917-1918
1914
1914
1872 (original); 1909 (model)
1914-1918
1915