NOTE ON TINFOIL GRATING AS A DETECTOR FOR ELECTRIC WAVES. 



1!) 



Experiment 6. 



I now placed my tinfoil grating within a glass bell-jar which 

 was covered with tinfoil strips. I found that even in this case the 

 change of resistance was distinctly perceptible. Thus: — 



This result may be taken to indicate how imperfect would be 

 the protection of an ordinary metallic gauze against powerful electric 

 oscillations. 



Experiment 7. 



A circular copper plate 30 cm. in diameter was vertically 

 suspended in front of the vibrator. My tinfoil grating placed behind 

 the plate at a distance of about 12 cm. from it, shewed the follow- 

 in g; changes in resistance : — 



Next, the distance between the plate and the grating was dimi- 



nished to 2*5 cm. The changes were as follows :■ 



