ox PHYSIOLOGICAL APPLICATIONS OF THE PHONOGRAPH. 529 



argument should be based only on records obtained from the phonograph 

 itself, which is furnished with a vibrator tliat will not record its own 

 periodic vibrations unless the sound be remarkably intense. In ordinary 

 voice production and in ordinaiy singing the vibrator of the phonograph 

 faithfully records only the pressures falling upon it — no more and no 

 less. 



(3) Recording Intensity of Tones. — I shall now show you another 

 method of recording, not the individual vibrations of tlie phonograph, but 

 the variations in intensity of the sounds of the phonograph — the inten- 

 sities of individual notes and chords. I was led to use this method by 

 becoming acquainted with an instrument devised by Professor Hiirthle, 

 of Breslau. He has succeeded in recording the vibrations of the sounds 

 of the heart. I saw that his instrument was very useful, and I adapted 

 it to the particular purpose in hand. Hiirthle's instrument is an electro- 

 magnet acting on a metal plate connected with the elastic membrane of a 

 tambour. Another drum is connected with the first by an india-rubber 

 tube. The metal plate of the first tambour is pulled down by the electro- 

 magnet ; thus the air is rarefied in the tube and in both tambours, and 

 the lever of the second tambour moves. The next instant the lever flies 

 back. We shall now connect ( ^raham's variable resistance apparatus with 

 tlie phonograph. As sound waves fall on it a change is produced in the 

 current passing through the electro-magnet ; the latter acts on its tam- 

 bour ; a variable pressure is communicated to the other tambour ; and if 

 the lever of the latter is brought against a revolving drum, a tracing is 

 obtained. Each note and each chord are recorded, so that you get a 

 mechanical tracing of the variations of intensity. 



(4) Electrical Stimulation of the Fingers by the Rhythm and Varying 

 Intensity of Tone. — Now this experiment suggested another of a different 

 kind. Suppose I send the current not only through the variable resist- 

 ance apparatus above the disc of the phonograph, but also through the 

 primary coil of an induction machine. The wires from the secondary coil 

 pass to two platinum plates dipped in weak salt solution. I now set the 

 phonograph going ; and when I put my fingers into the beakers contain- 

 ing salt solution, I feel the intensity of every note. The variation of 

 intensity, the time, the rhythm, and even the expression of music, are all 

 felt. I shall now place on the mandril of the phonograph a cylinder on 

 which has been recorded another piece of music, which is much quicker. 

 I now feel a series of electrical thrills corresponding to every variation of 

 intensity of sound coming from the phonograph. That method shows that 

 the nerves of the skin can be stimulated by irritations coming to it at 

 the rate of the notes and chords of I'apid music. Some of the notes pro- 

 duced by the phonograph do not last longer than the five hundredth or 

 six hundredth part of a second, but they are quite sufficient to stimulate 

 the nerves of the skin, and, as I have pointed out, you can appreciate the 

 variations of intensity. You c&n feel the long-drawn-out notes from the 

 saxhorn or tioiubone. You feel the crescendo and diminuendo of 

 rhythmic movement, and you can estimate the duration of the note and 

 chord. You feel even something of the expression of the music. It is 

 rather a pity to say that even expression is mechanical. It is undoubtedly 

 mechanical when you deal with the records of the phonograph. A number 

 of interesting questions of a physiological nature are suggested by this 

 experiment. Tlie skin is not a structure that can analyse tone or distin- 

 guish pitch ; it cannot tell you the number of vibrations, although there 



1897. M M 



