
Henley needle galvanometer, 1855-1860
1855-1860
1855-1860
1963
1935-1978
1932
11 February 1936
unknown
24 June 1935
27 June 1935
27 June 1935
26 June 1935
24 June 1935
03 July 1935
03 July 1935
29 June 1934
02 July 1934
29 June 1934
03 July 1936
01 July 1936
01 July 1936
04 July 1934
04 July 1934
July 1934
July 1934
25 June 1934
July 1934
11 April 1938
25 September 1934
circa 1906
circa 1906
circa 1906
1930s
1930s
9 March 1931
1930s
1930s
unknown
1935
1933
1930s
1930s
1930s
1930s
1930s
1930s
1930s
1930s
1930s
1930s
1930s
1930s