
Obsidian possibly used in trephination experiments
1918-1920
1918-1920
1935
1935
1920-1925
1917
1934
1919
circa 1915
1936
1915-1925
1926
1931
circa 1920
1927
1927
1915
1920
1915
1924
circa 1930
1928
1918
1914-1920
1936
1920-1929
1934
1932
1915-1925
1932-1936
1934-1935
1934
1916
1914
1931
1931
1915
1936
1927
1930
1915
circa 1930
1920-1925
1917
1928
1918
1932
1933
1925
1914
1924