18 PHYSICAL EXPEESSION. 



almost disappears. So sensitive is this flame that 

 even a chirp made at the far end of the room brings 

 it down more than a foot. Like a living being, the 

 flame trembles and cowers down at a hiss ; it 

 crouches and shivers as if in agony at the crisping 

 of this metal foil, though the sound is so faint as 

 scarcely to be heard ; it dances in tune to the waltz 

 played by this musical box; and, finally, it beats 

 time to the ticking of my watch. How wonderful 

 are all these facts ! And the more we know of them 

 the more wonderful do they appear ; for this aston- 

 ishing change in the aspect of the flame is produced 

 by an infinitesimal portion of those almost inaudible 

 sound-waves, already enfeebled by their distance 

 from the flame.' " 



In the telephone we see an instrument of great 

 impressionability, but it exhibits more than this. 

 Two instruments being placed in electrical com- 

 munication, and the instrument having a battery 

 in the circuit, the vibrations of the voice com- 

 municated to one instrument are conducted to the 

 other ; that is to say, the one instrument is im- 

 pressionable, the second expresses the vibrations 

 received by the first, while the force received from the 

 battery is an active agent or factor in producing 

 the expression. In this arrangement we see an 

 impressionable part, a conductor of impressions, 

 an additional force thrown in, and a part solely 

 utilized in producing expression. 



The vibrations of the receiving disc are ended as 

 soon as they arrive, and no permanent impression 

 is left ; there is no retentiveness of the impressions 



