1576 
V. Acknowledgments 
The authors wish to acknowledge the assistance of G. Wertheim and 
C- Wingate in the analysis of the data. 
Appendix I 
An Improved Microcoulometer for the Calibration of Piezoelectric Gauges 
by 
A. Bs Arons and We Grube 
1. Introduction 
1-1 The aece powered microcoulometer which has been used for several 
326 for the calibration of piezoelectric 
years by this laboratory 
gauges has frequently proved inadequate when stability and high sensi- 
tivity were required. It was the object of this program to design a new 
instrument of suitable stability and sensitivity, capable of operating 
with very high input resistance, by taking advantage of recent develop- 
ments in electrometer tubes and electrometer circuits. 
2- Description of the circuit 
2el A diagram of the new microcoulometer circuit (designated LH) is shown 
in Figure 19. The input stage utilizes the Victoreen VX=414 electrometer 
tetrode, the input grid resistor being 10? megohmse The electrometer 
output feeds one side of a push=pull cathode follower stage, the other 
side of which can be positioned by control of its grid bias in such a 
way as to set an initial balanced condition of zero potential across 
- 100 
