Fleming valve no 23. Pink discolouration inside 1908-1910. No base. Large copper anode. Metal filament. Fleming valve no 23. Pink discolouration inside 1908-1910. No base. Large copper anode. Metal filament. End of valve has a ‘nipple’ protrusion, again at side with wire attached (loose at other end), wire then runs into valve and is attached to a copper sheet. Also wire at top. Gap in top is bunged with paper (?). The open top is in the shape of a triangle, with flattened off ends. ‘No 23’ on paper label on side, hand written.
Manufactured between May 1908 to February 1909 -- Referenced in JA Flemings notebook 'Laboratory Notes Volume IV -- Tests on Oscillation Valves -- May 1908-Feby 1909.
Asbestos Inspection - Non-Asbestos.
Production Notes
After looking at JA Flemings ‘Laboratory notes Volumes IV and V’, it seems unclear whether these valves were created by Fleming at UCL. Fleming mentions that the valves are delivered by Mr. Stearn. It seems most likely that he is referring to Charles Stearn, who, along with Charles Topham figured out how to manufacture filament by spinning it in 1898. He founded the Stearn Electric Lamp Company in 1907, which was one year before these tests took place. It is not clear whether Stearn manufactured full valves, so it is possible that they were modified by Fleming once they reached the Pender Laboratory. What is clear, is that the valves referenced in his notes are the same ones held in the Electrical Engineering collections, and that the old numbers were the ones given to them by Fleming. Any letters on these valves are referenced by Fleming as a ‘Stearn Number’ and match up to the ones written in his notes. He also notes that valves 6, 12, 15, 20, 22, 5, 11, 28, 55(V), 57(X), and 60(Z) were sent away, presumably to Marconi, but not broken.
UCL definitely kept the valves with the following numbers:
4, 8, 9, 10, 13, 14, 16, 17, 18, 19, 21, 23, 24, 25, 26, 27, 29(C), 30(E), 32(H), 33(J), 34(K), 35(L), 36(M), 38(O), 40(Q), 41(R), 42(S), 43(HI), 46(HII), 47(HII), 49(A), 50(A), 51(A), 52, 53, 54(U), 56(W), 58(Y), 59(Z), 61(Z4), 62(Z5), 63(Z6)
