i8 



NATURE 



{Nov. 4, 1880 



mica disks of equal diameter with the brass disk?. But | this arrangement was in no way preferable, for in practice 



Fic. 5. — The Articulating Piiotophone, The Transmitter. 



it was found that moisture was apt to penetrate at the Fig. 4 is a diagram which simply illustrates the action 

 surface of the bare mica, spoiling the ef.'e:f. I of the selenium receiver, and shows, firstly, the way of 



Fig. 6. — The Articulating Photophcne. The Selenium Receiver. 



connecting the alternate disks ; and secondly, that the current from the batter)' P cannot go round the telephone 



