.S7A' WILLIAM SIEMENS, F.R.S. 197 



We have another discoverer who has already thrown light upon 

 this subject, viz., Mr. Edison, of New York, the well-known dis- 

 coverer of the phonograph, who, in constructing a form of telephone 

 nt 1 his own, introduced carbon contact, which gave him resistances 

 variable with the amount of physical pressure he brought to bear 

 upon the carbon ; and I must say that this question of varied 

 resistance due to vibration will probably resolve itself simply into 

 :i <iuestion of pressure between particles of matter which are con- 

 ducting in themselves, but which are held so lightly in contact that 

 .pressure is needed in order to establish conductive continuity. 



I should have liked that something more had been said of this 

 discovery of the microphone, with reference to its two elder sisters, 

 the telephone and the phonograph, being of opinion that the three 

 only separate steps in the achievement of an advance in phy- 

 science which bids fair to be considered hereafter as one of 

 great moment, not only as regards telegraphy, but as a means also 

 of affording a more perfect insight into the nature of molecular 

 action. AV'e have heard from Mr. Willoughby Smith that in sub- 

 stituting crystalline selenium for carbon in the microphone, a ray 

 of light produces an effect analogous to mechanical vibration, and 

 announces itself in a report comparable to a clap of thunder, and I 

 can quite follow him in his arguments with respect to the matter. 

 His Grace the Duke of Argyll alluded to the application of this 

 discovery to physiological research, and I could have wished that 

 some of our learned physicians had taken up this point in the 

 discussion, because I believe myself that the influence of these 

 discoveries upon physiological research will be very great indeed. 

 One thing has occurred to me in considering these matters, which 

 I will take the liberty of mentioning. We have the remarkable 

 effect of the phonograph producing a record of sounds simply from 

 the indents given to a slip of tinfoil, which record can be re- 

 produced at any time. This strikes me as being an exceedingly 

 analogous case to the impress produced upon the brain by what we 

 hear and see. An impress is produced, which for the moment 

 seems lost, but which in a .vigorous mind can be reproduced at 

 any time. Now, the faculty of memory is not conceivable on any 

 other hypothesis but that of a mechanical record being left on the 

 brain and stored up for perhaps half a century to be restored in 

 the succession in which it has been laid down ; otherwise how 



