
McVitie Weston valve collection, Marconi WT Co Round valve, type T
circa 1914
circa 1914
1917
1916
circa 1919
1919
1916
1935
1919
circa 1913
1912
1931
circa 1925
1932
1919
1935
1932
1903-1907
1912
circa 1913
1931
1960
circa 1940
1923
1900-1920
circa 1935
1922-1923
1955