Fleming valve no 32 also marked H. Blue/black discolouration internally. Copper anode. Impossible to see inside. Eyelet base. Fleming valve no 32 also marked H. Blue/black discolouration internally. Copper anode. Impossible to see inside. Eyelet base.
Fleming valve with anode of copper paper.Tubular valve with possible tangtilum filiment (rather than tungstun), based upon the other valves of similar design. There is a copper discloration between the copper paper and the base, and a much darker, almost black discoloration above the copper paper.The discoloration makes is difficult to see inside the bulb. There is a wire fed through a hole in the side of the bulb. There is a metal base with two eyelets attached to the bottom. A number 32 is written on the outside of the bulf over the copper paper. There is also an H marked in black on the metal base with a gold H next to it. There is some reside on the outside of the bulb.
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.
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)
