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Prof. J. A. Fleming on the Electric 



lijThe wave detector used was ? of the thermoelectric type, 

 and made as follows : — 



A glass test-tube had four platinum wires sealed through 

 the bottom (see fig. 5) . These were soldered to four copper 

 strips spaced apart on the inside of the test-tube. On the 

 external side at the base one pair of platinum wires were 

 connected by a fine constantan wire a b about 1 cm. long and 



Tellurium-Bismuth vacuum thermal detector for electric oscillations. 



ab. Constantan wire. cd. Thermoj unction. GG. Galvanometer terminals. 



00. Antenna and earth terminals. 



0*02 mm. in diameter. The other pair of platinum wires 

 were connected with small pieces of bismuth wire and 

 tellurium which were soldered to each other and to the centre 

 of the constantan wire, thus making a thermoelectric junction cd 

 with one junction on the constantan wire. This test-tube was 

 then sealed into another vessel which was highly exhausted, 



