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ANNALS NEW YORK ACADEMY OF SCIENCES 



the grid circuit, causing radio frequency variations of the wing current, 

 the potential of the wing with respect to the filament varies as the react- 

 ance voltage of the wing inductance alternately adds to and subtracts 

 from the voltage of the battery. When a negative capacity charge is 

 placed on the grid, the wing current will be reduced and the direction of 

 the reactance voltage of the wing inductance will therefore be the same as 

 the voltage of battery B^. The reactance voltage will therefore add to 

 the battery voltage, and the difference of potential between wing and fila- 

 ment and also between wing and grid will be increased. Similarly, when 

 a positive charge is placed on the grid the wing current is increased 

 and the reactance voltage of the wing inductance opposes the battery 

 voltage, producing a decrease in the potential difference between grid and 



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\Ce 



Fig. 19 



Fig. 20 



wing. Hence, supposing a negative capacity charge is placed on the 

 grid, the tendency of the corresponding increase in the potential of the 

 wing with respect to the grid will be to draw more electrons out of the 

 grid, thereby increasing the charge in the condenser formed by the wing 

 and grid, the energy for supplying this charge being drawn from the 

 wing inductance as the wing current decreases. The increased negative 

 charge on the grid tends to produce a still further decrease in the wing 

 current and a further discharge of energy from the wing inductance into 

 the grid circuit. On the other hand, when a positive charge is placed on 

 the grid, the potential difference between grid and wing is reduced and 

 some of the energy stored in the capacity formed by them is given back to 

 the wing inductance. During this part of the cycle, electrons are being 

 drawn into the grid from the surrounding space to charge the grid con- 

 denser in accordance with the well known valve action, and this, in effect, 

 is a conduction current, so that a withdrawal of energy from the circuit 

 takes place. In spite of this withdrawal of energy, however, a well 

 defined resonance phenomena between the audion capacity and the wing 

 inductance is to be expected, and in the reception of signals such is found 



