THE CARBON MICROPHONE 



183 



Figure 19 shows the appearance of the complete setup with the 

 cover on the outside container. This begins to compete with cosmic 

 ray apparatus from the point of view of the amount of lead involved, 

 the outer container weighing about 600 lbs. Port-holes — one of 



Fig. 18 — Mechanical system and associated electrical apparatus as set up for single 



contact study. 



which appears on the near end of the box — permit adjustments to be 

 made on the apparatus within, thus eliminating the necessity for re- 

 moving the large outer cover which, as you may surmise from the 

 number of handles, requires the combined efforts of two men to 



