
Obsidian possibly used in trephination experiments
1918-1920
1918-1920
1934
1918
1935
1920-1925
1942
1952-3
circa 1919
1940
1915-1925
1830 (original); 1967 (model)
1925-1935
1925-1935
1919
1928
1940
1923
1921-1931
1914-1916
1935
1911
1927
1917
1936
1926
1920
1915-1918
1930-1940
1943
1938
1927
1936
1913
1934
1944
circa 1915
1915-1918
1668; 1924
1937
1930
1610; 1923
1925-1940
circa 1925
circa 1923
1926
1930s
1940
1927
1938
1915