Electrical news and engineering . oes not needany, because a different principle is used to accomplish de-tection. In order to explain this, let us consider a tube inwhich there is no grid and no plate battery. This you willremember is similar to the so-called Edison effect, al- ready mentioned at the beginning of this paper. Edisonplaced a plate within the bulb of his incandescent lamp andconnecting this plate with the positive end of the filamenthe was al)!e to obtai:i several milliamperes of current. Thiswas afterwards found to be due to electrons or particles ofnegative electricity (lowing
Electrical news and engineering . oes not needany, because a different principle is used to accomplish de-tection. In order to explain this, let us consider a tube inwhich there is no grid and no plate battery. This you willremember is similar to the so-called Edison effect, al- ready mentioned at the beginning of this paper. Edisonplaced a plate within the bulb of his incandescent lamp andconnecting this plate with the positive end of the filamenthe was al)!e to obtai:i several milliamperes of current. Thiswas afterwards found to be due to electrons or particles ofnegative electricity (lowing through the vacuous space ofthe lamp from the filament to the plate, and it is the con-trol of this stream of negative electricity by means of agrid which gives us tlie modern vacuum tube. Xow youwill notice that since the plate is connected direct to thepositive end of the filament, that it is at the same voltageas that end of the filament and therefore electrons do notflow from that end of the filament to the plate because, as. Fig. 2—Actual results from tube similar to peanut tube we kniiw. there must be a voltage between the filament amithe plate, that is to say, a B battery, in order to get aflow of electricity. Different Pressure Between Negative and Positive Ends However. Edison prubably used one hundred volts tolight tlic filament of his lamp and therefore the voltage be-tween the negative end of the filament and the plate wasone hundred volts, which answered very well indeed to drivethe current through the plate circuit. 1 think you willreadily see that every point between the negative and thepositive end of the filament is acted upon by a differentelectric pressure forcing electrons, beginning with one hun-dred volts at the negative end of the filament and diminish-ing to nothing at the positive end. You will see therefore,that there will be a corresponding flow of electrons. Theelectrons emitted from the negative end will be drawnalong tow-ards the plate very forc
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