1212 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 1953 



manufacture. Sections of conductive coating are deposited on this 

 cylinder as shown. These are used to initially polarize the material, and, 

 in use, to collect the charges produced by stressing the inner and outer 

 fibers of the cylinder. It is interesting to note that these elements can 

 be used to detect, by proper choice of connections, either radial or axial 

 accelerations. Through suitable external instrumentation both directions 

 can also be recorded simultaneously if desired. 



The above illustrations show but a few applications of this material 

 for detecting accelerating forces. Additional forms will suggest them- 

 selves, each of particular advantage for specific application. 



The sensitivity of an accelerometer is generally given in coulombs/g or 

 open circuit voltage. Its effective voltage output over a given frequency 

 range is a function of the characteristics of the associated equipment 

 including the connecting cable. Calibration in the lower frequency range 

 up to a few hundred cycles may be performed by vibrating the acceler- 

 ometer on variable frequency vibration machines or resonating spring 



OUTSIDE SILVER LINED 120* ON 

 OPPOSITE SIDES-INSIDE COMPLETELY s — ^. 

 SILVER LINED FOR LENGTH SHOWN 



(a) 



(b) 



Fio. 6 — (a) Metal cantilever type element and (b) radial and axial miniature 

 cantilever type accelerometer. 



