LOJV VOLTAGE CATHODE RAY OSCILLOGRAPH 151 



voice, is applied to one pair of deflector plates, while the radio fre- 

 quency output, with amplitude varying according to the low frequency 

 voltage, is applied to the other pair of deflector plates. The resulting 

 pattern on the screen is a quadrilateral of solid fluorescence, since the 



Fig. 7 



two frequencies are not commensurate. The two vertical sides 

 indicate the greatest and the least amplitude of the high frequency, 

 while the other two sides show the current-voltage characteristic of 

 the transmitter. Fig. 7 shows such a pattern (retouched) , the edges 

 being much brighter than the centre. The exposure was two minutes 

 using a Seed 23 plate and / 6.8 lens opening. 



