622 



ELECTRICAL MEASUREMENTS 



tographic plate is obtained by a falling weight and controlled by 

 means of the dash pot on the pillar below the plate holder, so 

 that the desired speed of the contact brushes may be obtained. 



FIG. 387. Hospitalier ondograph. 



The Hospitalier ondograph, 2 Fig. 387, is another arrange 

 ment of the same sort. By means of a pen actuated by a specia 



