234 RADIO WAVE PROPAGATION EXPERIMENTS 
age of the plate supply above ground. However, this 
output can be reduced to ground by the introduction 
of a cathode follower or more simply by three series 
sections of a resistor and glow tube connected in series. 
The output of the two-story amplifier is fed into the 
junction between the first and second sections while 
the output is taken from the junction of the second 
and third sections, where the first section is connected 
to the positive plate supply and the third section con- 
nects to a negative potential equal to one-half the posi- 
tive voltage. It is not necessary to make this addition 
to the present equipment. 
RECORDER ACCURACY 
It is possible to measure temperatures to less than 
Y, of a degree Fahrenheit and humidities to less than 
Y% of 1 per cent. However, this accuracy is not neces- 
sarily required for low-level atmospheric soundings 
and construction of M curves. 
CoNCLUSION 
Direct automatic recording of low-level temperature 
and hygrometer readings is suggested. The method is 
especially adaptable for fixed or shipboard station 
operation. 
